Hi everyone,

As we are now within a week of starting the 2025 Montreal Fireworks Competition, I thought that it would be appropriate to release this thread in preparation for that.

As always, preliminary and finalized weather forecasts will be provided here prior to each display. Preliminary details will typically appear approximately two days before display times, followed by finalized forecasts by about a day before actual displays. These forecasts will include information pertaining to temperature, humidity, rainfall opportunities, as well as wind speed and wind direction. In situations where (severe) thunderstorms or rainfall altogether become important, or in cases of weak/strong wind fields (or precarious wind direction), additional brief updates will be provided. As with 2023, where applicable, air quality will also be included in forecasts due to the ongoing wildfire situation in the Canadian West.

Let's hope for ideal weather conditions for all displays, and for each setup period!

Trav.

Thanks Trav! Looking forward to your forecasts again!

All the best,

Paul.

No problem, Paul! Always a pleasure! It could prove to be an interesting Summer with respect to the weather!

Cheers,

Trav.

Being situated North of a stationary (warm) front, and under the influence of a shortwave trough, largely cloudy conditions are favored for the opening display day (June 26th). At the same time, periods of scattered light rainfall during the afternoon (a 60% probability so far for this situation) and stretching to potentially the late-evening will act to keep conditions cool and nearly saturated as the shortwave overspreads this region. As such, a maximum temperature of 21-22 C is favored for the greater Montreal area, which would be achieved during the late-morning to early-afternoon before rain-cooled air takes place principally by the mid-afternoon. At maximum cooling during the mid-afternoon period, a temperature of 14-15 C would unfold and be sustained going forward. With saturation, moderate humidity would be achieved. Under these conditions, a light jacket and/or thick sweater would be necessary with prolonged exposure outdoors.

Winds should be in the form of light ENE to NE (7-9 km/h), including for the evening. This would allow smoke accumulation, at all altitudes to evacuate slowly and directly away from and slightly to the left of the La Ronde audience. However, those watching from Notre-Dame and De Lorimer Streets should try to displace away from the bridge (i.e. in the direction of the Olympic Stadium) to avoid viewing obstructions from smoke accumulation. Although smoke density shouldn't be particularly high, damp and saturated air would sometimes encourage sizeable accumulation at low-altitude, and/or during more energetic segments. The lower cloud ceiling would also sometimes hide portions of upper-level shells, and nearly saturated air would occasionally cause colors to appear somewhat faded.

Another update to follow this late-evening into predawn (June 25th-June 26th) to confirm or revise these details, especially in terms of rainfall persistence beyond the afternoon.

Trav.

Details described in the post above remain largely applicable for today (June 26th), though with some revisions. As such, presented here are the weather conditions for the greater Montreal area.

Temperature/Humidity

A maximum temperature of 21 C is likely, achieved by mid-afternoon, making this one of the coolest daytime highs/maximum temperatures to appear this month. Humidity would be low, and so a Humidex would not be applicable. By late-evening, around display time, the air cools to 17 C under continued low humidity. A light sweater or light jacket could be useful for the evening, though the light winds would thankfully not amplify the chill in the air greatly.

Precipitation

The aforementioned shortwave trough continues to have some influence on the region for principally the early-afternoon. This would induce significant cloud coverage, as well as scattered periods of light rainfall (60% probability at the time). Rainfall quantity itself would be limited due to generally lower intensity and duration. Following the early-afternoon, skies should be remain cloudy under mid- to high-altitude cloud cover. However, one revision here is that the light rainfall would not persist beyond this period, as the trough would send this farther South of the region. As such, mostly high-altitude cloud coverage would persist for the remainder of the afternoon through to the evening, along with some clear breaks that may very well offer some window of opportunity to briefly reveal the sunset as a high pressure zone temporarily slides South. Under this revision, cloud ceiling should ultimately be higher (mid- to high-altitude cloud) than what was previously suggested in the above posting.

Wind

Wind fields continue to be quite light from the East to ENE (4-7 km/h) for the late-afternoon to evening North of that stationary (warm) front, though the winds would be breezier from the NE (17-21 km/h) for the early- to mid-afternoon. This would allow for smoke accumulation, at all altitudes, to move gently towards the Notre-Dame audience (and correspondingly very slowly away from the La Ronde audience). Thankfully, as mentioned, humidity would be low, so larger smoke density is not favored. However, the display would often still appear hazy/foggy from Notre-Dame/De Lorimier Streets and adjacent sections of the bridge, especially venturing deeper in the display and at low-altitudes when the display grows more active (and if/when more smoke-rich products are used at times).

*Another update will appear here, if necessary, for evening wind speed/direction.

Trav.

Latest data reveals similar wind velocities for this evening. In addition, the clear breaks expected for this late-afternoon to evening would stretch to capture this mid-afternoon with an earlier Southward ejection of the aforementioned high pressure zone. It should already be sunny downtown and Eastward/NE, with this soon reaching the West Island and West. As such, a clearer mid-afternoon to evening is favored with patches of cirrus, but still with a somewhat cool late-evening temperature (17-18 C).

Trav.

Indeed now the sky has cleared and it's beautifully sunny downtown. Looks like it will be the perfect evening, even if it's not so hot as we've had recently!

Paul

Hi Paul — Yes! The clearing has just also recently reached out here in the West Island-Vaudreuil corridor! We had some light rain earlier this afternoon that came in from Ottawa, but I believe that it stayed dry farther East over greater Montreal and East/NE/SE of there. Looks like we'll, indeed, be able to take advantage of this clearing, and so it will capture more than just around sunset!

Trav.