Pembroke is in for a stretch of hot weather this week, with temperatures climbing roughly four degrees above the early August norm and the UV index reaching a very high level of 9. Environment Canada is calling for a high of 29 to 30 degrees Celsius under mainly sunny skies on Wednesday, and a high of 27 on Thursday under mainly cloudy skies, though no formal heat alert has been issued because the humidex is expected to stay below Ontario’s warning threshold.
Despite the heat, Environment Canada has not activated a heat warning for the Pembroke area. Ontario’s Harmonized Heat Warning System, detailed by the province, kicks in for Northern Ontario communities when the daytime high reaches 29°C and the overnight low stays at 18°C or higher for two consecutive days, or when the humidex reaches 36 or higher for two or more days running. As of Wednesday afternoon, observations from the Garrison Petawawa station showed a temperature of 29.3 degrees and a humidex of 32, leaving conditions just shy of official alert criteria.
Thursday’s outlook calls for a high of 27 degrees with a humidex of 34, but the main concern is the very high UV index of 9. Environment Canada says a mix of sun and cloud will dominate through the weekend, with a 40 percent chance of afternoon showers and a risk of a thunderstorm late Thursday. Normal highs for this time of year sit at 25 degrees, with overnight lows around 13, so the current warm spell is a notable departure from seasonal averages.
Residents are encouraged to take personal steps to stay safe during peak afternoon hours, especially between 11 a.m. and 3 p.m. when UV radiation is strongest. The UV index, first created by scientists at Environment Canada in 1992, measures the strength of the sun’s rays, and a reading of 9 means people should use a high-SPF sunscreen, wear protective clothing, and seek shade. Keeping hydrated is also important, even without an official heat warning in place.
While the current temperatures sit above normal, they remain far below the record heat Ontario endured in July 2026, which saw the province’s hottest temperature in 90 years and the humidex hit 46 in nearby Ottawa on Canada Day.
