Maritimes brace for heat, humidity and scattered thunderstorms
Heat and moisture move into the Maritimes, causing scattered thunderstorms, before cooler air returns Thursday.
Warm, humid air settles over the Maritimes on Tuesday as a moisture surge moves in from the Gulf, raising humidity and triggering scattered showers and thunderstorms later in the day.
Humidex levels are expected to rise into the high 20s to low 30s in New Brunswick, with eastern inland Nova Scotia also experiencing sticky, summer-like conditions.
An incoming system moving out of Ontario and Quebec will contribute to scattered thunderstorms by late Tuesday. While severe weather is not expected, some storms may bring brief heavy rain, small hail and gusty winds, with the strongest signals for activity near and south of Fredericton.
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Storm chances peak late Tuesday
Tuesday's late afternoon and evening hours are thought to be the best time for thunderstorm development, when instability peaks and moisture levels are at their highest.
Any storms that form will be fast-moving and unevenly distributed, so some communities may experience brief heavy rain while nearby areas remain mostly dry. The main concern is still localized downpours, rather than organized severe weather.
Conditions will gradually improve overnight as the initial system moves away, but the humid air mass will remain through Wednesday.
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Heat peaks Wednesday before cooldown
Wednesday is forecast to be the warmest and most widespread day of the stretch, with temperatures reaching the 30s in parts of New Brunswick. Halifax and the surrounding areas could see humidex values near 30, resulting in another muggy day even without any shower activity.
As lingering moisture interacts with daytime heating, a second round of mostly non-severe thunderstorms could form late Wednesday into the early evening, particularly near the Bay of Fundy.
By Thursday, a cooler air mass is projected to return to the region, lowering temperatures back to seasonal norms in the teens and providing a noticeable break from humidity.
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