October thunderstorms rattle around southern Quebec - Isaias first hurricane of 2026

The third thunderstorm in less-than 12 hours moved across the region early Thursday morning. The storms produced lots of lightning but no severe weather was reported. They were fast moving, resulting in just 5-10mm of rain on average across the Montreal area. (Valley Weather)

Several rounds of thunderstorms crossed the Montreal region over the last 24 hours. That included some rare nocturnal October storms just after midnight, that put on quite a sound and light show. The storms were fast moving, and outside of some vivid lightning and gusty winds, only 5-10mm of rain fell. Lightning strikes did manage to shut down the weather weary REM commuter trains to the south shore for several hours Thursday morning.

Just enough instability in the atmosphere will be present again Friday afternoon for perhaps another isolated, non-severe storm. Small hail and gusty winds will be possible. Otherwise high pressure will build into the region for Saturday and most of Sunday, resulting in fair skies. 

Temperatures will start the forecast cycle chilly, only reaching 13C (55F) Friday after morning lows near 5C (41). We can expect warmer highs both Saturday and Sunday as southerly winds develop between a Bermuda high off the Atlantic coast, and the remnants of hurricane Isaias moving north from the Gulf of Mexico into the Ohio Valley. The warm south winds will push highs close to 20C (68F) in Montreal.

By Sunday night and into Thanksgiving Day, clouds and perhaps a few showers will begin moving north across New England and into southern Quebec from what is left of Isaias.

NOAA image of Hurricane Isaias in the southern Gulf of Mexico late Thursday.

Hurricane Isaias

It has been a record-breaking quite hurricane season in the Atlantic basin to date, with only nine named storms and the latest we have had to wait for a hurricane to form. That record was set way back on October 7, 1905. It took until 7pm Wednesday evening for the first hurricane of the season in the Atlantic. Meanwhile the Pacific has recorded 19 storms, 9 of which have become hurricanes, 6 major storms, category 3 higher. The El Nino fueled Pacific hurricane season has resulted in over $682 million dollars in damage and 18 deaths.

Back to Isaias, as of Thursday evening the center of the strengthening storm was located in the Gulf of Mexico, 525 km south of the Mississippi River. The storm was moving northeast at 19km/h, with 160km/h winds, a category 2 hurricane. Isaias has prompted hurricane warnings along the Gulf coast from Florida to Mississippi. The storm should make landfall late Friday or in the pre-dawn hours Saturday, with a storm surge of 5-7 feet above sea level along the immediate coast.

Heavy rain, in excess of 150mm, will spread inland across the southeastern United States, north into the Ohio Valley.