Environment and Climate Change Canada upgraded the thunderstorm risk for the Montreal area on Thursday morning, issuing a watch that extends to parts of the South Shore, the Laurentians, Lanaudière and further north. The alert comes as warm, humid air moves through the region and while skies could reveal a deep partial lunar eclipse late Thursday into early Friday.
What the forecast says
Forecasters call for scattered showers during the afternoon with an elevated chance of thunderstorms into the evening. The daytime high is expected to reach about 24 C, with a humidex near 31, making conditions feel significantly warmer. The ultraviolet index is forecast at 6 — classified as high — so midday sun protection remains advisable.
Most of the precipitation is expected to taper off by midnight, though lingering cloud cover may persist into the overnight hours. The low will be near 19 C.
| Parameter | Value |
|---|---|
| High temperature (Thursday) | 24 C |
| Humidex | 31 |
| UV index | 6 (High) |
| Overnight low | 19 C |
Lunar eclipse timing and viewing prospects
The region is scheduled to see a deep partial eclipse of the full moon, with the moon entering Earth’s shadow late Thursday. The eclipse is not total but is substantial — listed at about 96.3 per cent. In the Montreal area the event is forecast to begin at 10:34 p.m., reach its maximum at 12:13 a.m. Friday and conclude by 1:52 a.m.
“The umbra’s dramatic effect will be easily visible as it takes an increasingly large bite out of the disk of the full moon,”
The shaded portion of the lunar surface is likely to take on a coppery tone rather than the deep red associated with a total eclipse. Skywatchers will need clear enough skies to see the shadowed limb of the moon; the presence of clouds overnight could limit visibility.
Impacts and precautions
Thunderstorm watches indicate conditions favourable for the development of thunderstorms. While not every watch results in severe weather, people should remain alert and be prepared to seek shelter if storms develop. The combination of warmth and humidity also contributes to lightning risk and localized downpours.
- Monitor local forecasts and alerts from Environment and Climate Change Canada for updates on thunderstorm development and any escalation to warnings.
- Avoid standing under trees, open shelters or near metal structures during lightning; move indoors if possible.
- Secure loose outdoor items and be cautious of sudden gusts that can accompany cells.
- For eclipse viewing, plan to be flexible: cloud cover could obscure the event — consider multiple observation sites or check live-streams from observatories if conditions worsen.
- With a UV index of 6, wear sun protection during the afternoon hours despite cloud promise.
Practical tips for planning
Photographers and skywatchers aiming to capture the eclipse should prepare camera settings and equipment in advance and be ready to move locations if cloud cover becomes problematic. For general safety, keep up-to-date weather alerts on a mobile device and heed instructions from local public-safety officials.
Tonight’s weather setup — warm and humid with a chance of evening storms followed by variable overnight cloud — means residents will either get a dramatic view of the moon’s shadow or a cloudy show. Either way, being prepared will help you enjoy the spectacle and stay safe if storms develop.
Stay tuned to Environment and Climate Change Canada bulletins for the latest on the thunderstorm watch and any changes to the forecast for the Montreal region and surrounding areas.
