montreal-fireworks.com 2025 Schedule Report Blog

Montreal Fireworks Forum

 | Home | Register | Search | Statistics |
General Montreal Fireworks Forum / General /  
 

Weather Cooperation (or not) for Summer 2025.

 
 
Page  Page 2 of 3:  « Previous  1  2  3  Next »

Author Smoke
Member 
#16 | Posted: 10 Jul 2025 01:43 
Weather conditions mentioned in the previous posting remain mostly valid, but some revisions were made to convective rainfall coverage and wind velocity. As such, presented here are the dominant patterns favored for the greater Montreal area for July 10th.

Temperature/Humidity

As mentioned previously (post #15), a maximum temperature of 27-28 C would be present for the mid- to late-afternoon (Humidex of 35 C) for the greater Montreal area under borderline high to very high humidity. By mid-evening, this decreases to 23-24 C (Humidex of 30-31 C due to very high humidity). Under a rain-cooled situation, though less favorable, a late-evening temperature of 21 C (Humidex 28-29 C) would be likely.

Precipitation

Despite high available instability, lift remains too conservative through most of the day to drastically make efficient use of this environment, though with the predawn/early-morning period featuring some opportunity for isolated convective rainfall/non-severe thunderstorms (30% probability at the time, and then some scattered coverage later in the morning inducing a 40% probability). Beyond this, partly cloudy conditions should prevail, consisting of clusters of towering cumulus. That said, a secondary shortwave trough and a surface warm front would begin to offer improved ascent by mid-afternoon and moving forward into the mid-evening. During this timeframe, scattered thunderstorm/convective rainfall coverage would be favored (40% probability). Given the environment, some opportunity for at least few strong to severe thunderstorms would still be present. The latest thinking, though, is that these would be sparse and likely focused to near the New York and Vermont borders and North of the island of Montreal, where lift is maximized. As previously mentioned, these more organized thunderstorm families would be capable of locally strong downbursts, intense lightning, significant rainfall rates, and small- to medium-sized hail. Meanwhile, mostly cloudy skies (comprised of towering cumulus) would be present for the (late-)evening, with larger clear breaks between them.

Wind

Winds follow a SE flow for the day, resolutely holding light speeds (9-12 km/h). By mid- to late-evening, there are indications that the wind field would transition to SSW, though with slightly lighter speeds (6-8 km/h). Consequently, smoke accumulations, at all altitudes of the display, would be moving fairly slowly clear to the right of the La Ronde audience. That said, some periods of extensive smoke accumulation would be possible at low- to mid-altitudes of the display because of high to even very high humidity and light wind flow, notably during more energetic moments of the display. If smoke-rich products are further regularly used, this would amplify smoke accumulation. Therefore, right-hand sections of the display (La Ronde's right) at low- to mid-altitude would sometimes appear hazy/hidden. Once again, the laser segments would be beneficial in this case.

*If necessary, another update will appear here this afternoon (July 10th) for wind direction/speed, and convective rainfall coverage.

Trav.

Author Smoke
Member 
#17 | Posted: 10 Jul 2025 20:15 
Just to quickly update, wind fields should be more ENE to NNE (still light speeds, at 4-7 km/h), and so this would allow the (dense) accumulations of smoke to move more directly away from the on-site audience and to their left, and slowly towards those closest to the bridge near the river and closely adjacent portions of Notre-Dame Street. All other details presented in the above post (post #16) still apply. Thankfully, thunderstorm behavior/initiating zones aligned well with the expectations described above.

Trav.

Author Smoke
Member 
#18 | Posted: 16 Jul 2025 04:16 
For July 17th, a maximum temperature of 30 C (Humidex of 38 C) is possible for the greater Montreal area if convective rainfall/thunderstorms do not significantly affect the island. 23-24 C would be favorable during display time and still narrowly holding onto very high humidity (Humidex of 31 C). Beyond this, the temperature and humidity decrease quickly. If the cooler air mass ejects SE quicker, then cooler/less humid conditions would be more favored during the display.

For the fourth consecutive time, representing a record-streak in this competition's history, strong to severe thunderstorms could affect this general area for a fireworks day. As such, a Severe Thunderstorm Watch could again be enforced. That being said, it is also quite possible that actual display time will also avoid such events for a fourth straight time. A strong cold front and accompanying potent shortwave trough would be advancing SE through the day and would be the focus for scattered thunderstorm coverage, especially during the late-afternoon towards sunset when ascent becomes more aggressive. The primary hazards would be locally damaging straight-line winds with some of these thunderstorm families due to mostly their fast movement. The latest thinking, though, is that complete frontal passage would take place by around sunset, and so the greatest risk for thunderstorms would occupy the morning (30% probability) to notably mid- to late-afternoon (60%). Nevertheless, let's hope that thunderstorms again avoid the firing site collectively throughout the morning-afternoon to keep the risk for technical problems minimal.

At the same time, due to a sharp temperature gradient taking place behind the cold front, a fairly strong WSW to Westerly wind field could develop during the mid- to late-evening to early-predawn period. Winds would be mostly in the form of gusty Southwesterlies/SSW for the day, at 27-31 km/h (occasional gusts reaching 41-44 km/h). As the winds become more WSW to Westerly later in the evening, sustained speeds of 28-33 km/h would occur (occasional gusts reaching 43-47 km/h). This may, therefore, induce a delayed start to the display if air mass transition is allowed to occur sooner than later. Rapid smoke displacement would be present at all altitudes of the display, though the show would appear hazy for the on-site audience outside of laser segments, and especially if very high humidity is able to hold.

*Another update to follow this late-evening (July 16th) to early-predawn July 17th, notably for thunderstorms/thunderstorm character and evening wind speed.

Trav.

Author Smoke
Member 
#19 | Posted: 17 Jul 2025 02:19 
Weather conditions described in the above-posting (post #18) are still generally applicable. As such, here are the conditions for the greater Montreal area for July 17th.

Temperature/Humidity

29-30 C would still be within reach for a maximum temperature (Humidex of 38-39 C) if convective rainfall/thunderstorms hold off long enough before affecting the island. Due to the earlier onset of the cooler, drier air mass, one revision would be a cooler display temperature of 19-20 C under moderate humidity (Humidex of 23 C) as the air rapidly cools and dehumidifies during the evening.

Precipitation

A cold front and shortwave trough will migrate SE through the day. The nature of the environment would offer some opportunity for organized thunderstorms during principally the mid- to late-afternoon period among the scattered thunderstorms/convective rainfall that develop (60% probability collectively and 40% for thunderstorms). The predawn period of July 17th would feature sparse thunderstorms/convective rainfall (30%). As mentioned previously, this could invite another Severe Thunderstorm Watch for a fourth consecutive display day. The primary hazards with the most organized thunderstorms would be locally damaging straight-line winds, torrential rainfall, as well as an isolated weak tornado earlier in the afternoon. Lightning frequency would be somewhat more reserved, though moderate frequency would still be achievable. Fortunately, consistent with the last post, thunderstorms/convective rainfall should still evacuate the area completely by late-afternoon, just a little after traditional dinner time and before sunset. Following this, large clusters of less defined cumulus cloud would govern the skies, with sizeable clear breaks between them. Hopefully, the firing site avoids thunderstorms to keep the risk for technical problems minimal.

Wind

Winds would be in the form of breezy Southerlies to SW for the morning to afternoon, with sustained speeds and gusts of 24-28 km/h and 39-44 km/h, respectively. Just before sunset, the tendency would become SW to eventually gusty WSW to straight Westerlies just before and during display time. By display time, these do show signs of becoming breezy/gusty WNW, when speeds would be 29-33 km/h (occasional gusts of 43-47 km/h). This would allow the light smoke accumulation to drift very quickly towards central and left-hand sections of the La Ronde audience – particularly quick displacement is expected at higher altitudes of the display. This would cause the show to appear hazy at La Ronde outside of laser segments, even though thick smoke accumulation is not favored. Due to the gusty nature of the winds, it remains possible for this show to experience starting delays. Wind speeds generally weaken closer to midnight and beyond.

If necessary, another update will appear here this afternoon (July 17th) to address wind speed for the evening period.

Trav.

Author Smoke
Member 
#20 | Posted: 23 Jul 2025 02:16 
A return to a hot and very humid air mass would send the temperature to a maximum of 31-32 C (Humidex of 41-42 C) for July 24th, which could represent a new record maximum temperature for the day. For the late-evening period, the greater Montreal area would remain at 29-30 C (Humidex of 38-39 C), including display time. That said, the fanning effect of the gusty SSW/SW wind would help to reduce the purity of the apparent heat somewhat.

Limited lift for the day should keep the convective rainfall/thunderstorm risk minimal (for the first time since the opening show day), but it should be enough for some clusters of defined cumulus and cirrus to appear by late-morning. That said, some opportunity for isolated thunderstorms would exist during the predawn period, so this will be monitored in case the associated lifting features do speed up enough to capture the neighboring late-evening. Still, the greatest ascent for these thunderstorms is so far most likely to enter the region until deeper into predawn.

Due to strong warm air advection, winds would be in the form of gusty SSW/SW throughout the day. Wind speeds would be sustained at 28-33 km/h (occasional gusts of 44-48 km/h), including the evening. This would allow the rapidly accumulating smoke to drift very quickly towards right-hand sections of the La Ronde audience at all altitudes (partly central with respect to upper-level smoke). Due to this pattern, the show would often appear hazy at low- to mid-altitudes at its right-hand portions from La Ronde's perspective (outside of laser segments). Since the wind speeds would again be quite gusty at times, near-similar to the Swiss display, this could potentially cause starting time delays for this display. As such, wind speeds would additionally be monitored.

*The next update will appear here by later this evening (July 23rd) into predawn (July 24th).

Trav.

Author fredbastien
Member 
#21 | Posted: 23 Jul 2025 09:12 
Hi Trav, just few words to let you know about my appreciation for your precise weather forecast, which I assiduously read. Thank you.

Let's hope that we avoid rain once again tomorrow night!

Fred

Author Smoke
Member 
#22 | Posted: 24 Jul 2025 04:09 
Details presented in the previous post (post #20) continue to be applicable for today (July 24th). Therefore, here are the conditions most favorable for the greater Montreal area:

Temperature/Humidity

The hot and very humid air mass would yield a potentially record maximum temperature for today, at 32-33 C (Humidex of 41-42 C). For display time, the temperature would remain at 29-30 C (Humidex of 38-39 C). For those not comfortable with higher heat and humidity, the breezy SW winds for the evening (and more so during the day) would offer some relief via a fanning effect by reducing the apparent heat.

Precipitation

A cold front and strong shortwave trough would be advancing ESE through principally the predawn/overnight period, causing scattered thunderstorm coverage among a widespread distribution of convective rainfall. As raised as a possibility in the previous post, recent data indeed reveals a slightly faster acceleration of these lifting features, enough that they would begin to have some influence during the neighboring late-evening of July 24th. Latest thinking, though, is that this deep convection would stall enough until (narrowly) after display time and into the previously suggested predawn period, although this would have to still be monitored due to the now tighter timing of this involved ascent. Nevertheless, mostly cloudy conditions (under a cumulus/cirrus cloud deck) with small clear breaks would be present for the evening, but it is possible to observe distant lightning to the West/NW later in the evening. Lightning frequency itself would be moderate at best with thunderstorms. The situation may also prompt a Severe Thunderstorm Watch for mostly the early-overnight, even though thunderstorms should largely remain non-severe in this general area.

Wind

Winds continue to be in the form of gusty SSW to SW for the day, with sustained speeds of 29-33 km/h and accompanying gusts that occasionally would reach 48-52 km/h. That said, one (important) revision made here is that wind speeds would decrease to somewhat lesser values by the mid- to late-evening under a SW flow, at 22-26 km/h (occasional gusts of 33-37 km/h). This would allow the rapidly accumulating smoke (due to very high humidity) and some pyrotechnic debris to advance fairly quickly towards right-hand sections of the La Ronde audience, though with upper-level smoke displacing towards right-hand (and partially central) sections more swiftly overhead. Outside of laser segments, this would also cause right-hand sections of the display to regularly appear hazy from La Ronde's vantage point, though perhaps also giving the lasers an interesting smoke effect at the right.

*If necessary, another update will be provided this afternoon (July 24th) for wind speed and/or thunderstorm risk.

Hi Fred – you're most welcome for the weather forecasts! Always a pleasure! And yes, even through the situation has grown more fragile for the late-evening, let's hope that we continue rain-free (and under safer wind speeds) during display time!

Trav.

Author Smoke
Member 
#23 | Posted: 24 Jul 2025 18:09 
No changes to make to post #22 concerning this evening (July 24th). Wind speeds, as suggested above, would remain relatively high for the evening despite some decrease not too long after sunset. Gusts are, as such, likely to still occasionally be close to the 40 km/h threshold (33-37 km/h gusts) late this evening.

The thunderstorm risk also remains valid for late this evening — if the display is allowed to fire on time (i.e. no (significant) delays caused by too strong SW winds)), it should narrowly avoid interaction with thunderstorms/convective rainfall given the timing of the greatest ascent in the area, although it should be noted that preliminary isolated thunderstorms can appear in the area beforehand as lift generally increases through the evening collectively.

Trav.

Author Norandois
Member 
#24 | Posted: 24 Jul 2025 19:00 
I'm on the bridge right now and it was damn hot despite some shadow on pedestrian side. Still windy but the good part is the smoke and debris not gonna fall on our side defenetely, the show look massive from up there!

Author Smoke
Member 
#25 | Posted: 24 Jul 2025 21:44 
Gusts have indeed been more regularly below 40 km/h slightly (closer to 30-35 km/h) over the last 90 minutes, so we should be safe going forward. However, yes, another breezy evening. A few distant lightning strikes from the dying thunderstorms to the NW, as well.

Trav.

Author fireworksforum
Admin 
#26 | Posted: 25 Jul 2025 08:59 
Smoke:
A few distant lightning strikes from the dying thunderstorms to the NW
I saw these from around 9:15 to 9:30. We got a few drops of rain towards the end of the display, but maybe that was smoke causing nucleation in the very humid air! Amazingly the rains avoided us entirely!

Author Smoke
Member 
#27 | Posted: 26 Jul 2025 04:40 
The final in-competition display day (July 27th) would be part of a potential heat wave July 26th-July 29th), featuring a maximum temperature of about 31-32 C under very high humidity (Humidex of 41-42 C) for the greater Montreal area. A similar display temperature to the American display should also be observed (29 C, with a Humidex of 38-39 C). At the same time, a gradually stationary warm front will advance NE and would be the focus for scattered convective rainfall (including isolated thunderstorms) during the late-morning to mid-afternoon period. Therefore, a partly cloudy sky composed of defined cumulus is favored in this environment. The evening would be under clusters of cumulus cloud with large clear breaks between them.

Winds should be in the form of breezy SSW for the day (17-21 km/h – occasional gusts of 28-32 km/h). This would continue for the evening period under lighter speeds (9-12 km/h) and so would allow the rapidly accumulating smoke to correspondingly drift somewhat slowly to the right of the La Ronde audience, making far right-hand sections of the show regularly hazy. Upper-level smoke would be moving quicker and more so towards right-hand sections of the La Ronde overhead.

*Another update will appear here late this evening (July 26th) into predawn (July 27th).

Hi Paul – yes, we were lucky to be rain-free yet again during display time, despite distant thunderstorms in the general area just closely before (NW) and after (West/SW) the display! Remarkably also 5 consecutive Severe Thunderstorm Watches (including one Warning — July 17th) for fireworks days – definitely never seen before in this competition's history!

Trav.

Author Smoke
Member 
#28 | Posted: 27 Jul 2025 02:26 
Details presented in the above posting (post #27) remain applicable, although with some revisions presented below. As such, here are the dominant weather conditions for the greater Montreal area for July 27th.

Temperature/Humidity

In light of continued wildfire smoke overspreading the region, a slightly lesser maximum of 29-30 C is expected under very high humidity (Humidex of 39-40 C). A display temperature of 28-29 C, with a Humidex of 38-39 C should also be registered.

Precipitation

A warm front will be positioned over East Ontario and will be the focus for scattered convective rainfall (40% probability), including isolated thunderstorms (30% probability) for the late-morning to late-afternoon period. Fortunately, the extent of ascent would be limited, and so convective coverage should remain scattered at best. Thunderstorm severity would also generally remain sub-severe, but the environment would offer some window of opportunity for sparsely-distributed strong to severe thunderstorms. The sky would be occupied with defined cumulus throughout the day, including with evening clusters of cumulus with large clear breaks. Skies would additionally appear somewhat hazy due to continued Western Canadian wildfire smoke, although air quality would represent an improvement from yesterday.

Wind

Winds remain under the breezy SSW tendencies mentioned in the above posting. However, one important revision here is that winds would turn more westerly by mid-afternoon, and eventually light WNW (still 9-12 km/h) in time for late-afternoon and throughout the evening. This would allow rapidly accumulating smoke, at all altitudes, to advance somewhat slowly towards the La Ronde audience more directly, focused to central and left-hand sections. Due to very high humidity, the display could, therefore, appear quite hazy for the on-site audience from notably low- to mid-altitude outside of laser segments, notably deeper into the display when there are more smoke-rich products along low-level and during more active moments. Some chance exists for the wind fields to change to NW in time for the display, which would be more helpful, and so this will be addressed in an upcoming update this afternoon, if necessary.

*Another update, if necessary, will appear here this afternoon (July 27th) for evening wind behavior and/or thunderstorm coverage.

Trav.

Author Smoke
Member 
#29 | Posted: 27 Jul 2025 21:05 
Just to provide an update — latest and recent data reveals that a more SSW to SW flow would be favored for this late-evening/July 27th (closer to what was envisioned in post #27), allowing for something similar to the American display, but with slower wind speeds (still 9-12 km/h). As such, the rapidly accumulating smoke would be slowly advancing towards far right-hand sections of the La Ronde audience (and partially central sections with respect to upper-level smoke, which would be moving quicker). This would make right-hand portions of the display often hazy outside of laser segments. Skies will also be largely clear, with a few distant residual cumulus clusters.

Trav.

Author Smoke
Member 
#30 | Posted: 29 Jul 2025 23:57 
For this final display day of 2025 (July 31st), it would be the first and only one that is truly free of a rain/thunderstorm development risk for this general area. As such, the situation for the closing display would ironically resemble the opening show's conditions, except without the scattered early-day rainfall, and a slightly different wind direction.

With a broad zone of high pressure settling SE, and given substantial cloud cover, a maximum temperature of 24 C is favorable. Also being bound to some of the lowest humidity this Summer, a Humidex is negligible, as would be the case for the evening. Display time itself would feature a temperature of 19-20 C, being potentially tied with the Italian show for the coolest display time temperature this year.

While rainfall is not favored, significant cloud coverage in the form of a cirrus and cumulus cloud deck would overspread the region. This blanket of cloud would be driven by a stationary front positioned in the United States Northeast, spreading far enough to the North to capture this region. That said, there are indications that this cloud deck would begin breaking apart into the evening period to allow for some clear breaks.

Winds are in the form of somewhat breezy NNE during the day (13-17 km/h). This would then turn into a light NE flow for the late-afternoon to evening (9-12 km/h). As such, the light smoke accumulation, at all altitudes, should be moving slowly towards those sections of the bridge nearest to the river (and to the Old Port), much like during the Italian and Japanese shows.

*Another update will appear here tomorrow late-evening (July 30th) to predawn July 31st to confirm these conditions.

Trav.

Page  Page 2 of 3:  « Previous  1  2  3  Next » 
General Montreal Fireworks Forum / General /
 Weather Cooperation (or not) for Summer 2025.

Your Reply Click this icon to move up to the quoted message

 

  ?
Only registered users are allowed to post here. Please, enter your username/password details upon posting a message, or register first.

 

 
 
Montreal Fireworks Forum Powered by Simple Bulletin Board miniBB ®


  ⇑