First Heat Event of the Season Cranks Up the Heat Across Eastern Lac Seul Region

SIOUX LOOKOUT – WEATHER REPORT – Sioux Lookout and Eastern Lac Seul are officially stepping into the heat zone as Environment Canada has issued a Heat Warning for the region. This is the first heat event of the season, and it’s coming in strong with highs pushing into the high 20s and low 30s, along with muggy nights that may leave residents tossing and turning.

Heat Kicks Off Today: Forecast Through Thursday

At 6:00 AM CDT this morning, the temperature at Sioux Lookout Airport was a comfortable 10.3°C under mostly cloudy skies. The dew point is at 4.3°C, with humidity at 66%, while winds remain light from the east-southeast at 8 km/h. Barometric pressure is 101.1 kPa and falling, paving the way for the hot air mass to settle in.

Today will bring a mix of sun and cloud, with a 30 percent chance of showers and the risk of a morning thunderstorm. Winds will shift to the south by mid-morning, picking up to 30 km/h and gusting to 50 km/h. The high will soar to 29°C with a humidex of 30, and the UV index will climb to 7—meaning it’s a day for sun protection even if clouds are floating by.

Tonight, skies will clear, but the heat will linger with an overnight low of 18°C—offering little in the way of cooling. Winds will ease slightly to 20 km/h from the south.

Tuesday is set to be another scorcher with clear skies and a high of 29°C, paired with a UV index of 8, officially in very high territory. South winds will once again gust to 50 km/h, so batten down the patio furniture. Tuesday night will remain clear and slightly cooler with a low of 14°C.

Wednesday brings a mix of sun and cloud and a 30 percent chance of showers, with the high easing to 26°C. The night will see cloudy periods with another 30 percent chance of showers and a mild low of 13°C.

Thursday ushers in a more significant pattern change, bringing cloudy skies with a 60 percent chance of showers and a cooler high of 22°C. The showers are expected to continue into Thursday night with a low of 8°C—finally offering a more typical Northwestern Ontario May evening.

Beat the Heat: Dress Light and Stay Hydrated

With these temperatures more suited for mid-summer than May, now is the time to break out those loose, light-coloured clothes and wide-brimmed hats. Keep hydrated throughout the day, and schedule any outdoor activities during the cooler parts of the morning or later in the evening. And remember: this is not the week to leave pets or kids inside parked vehicles.

Historical Weather Snapshot for May 12

Sioux Lookout’s record high for this day is 30.8°C, while the record low is -2.4°C. With today’s forecast high sitting at 29°C and tomorrow’s matching it, we are skimming close to historical territory, reminding residents how quickly spring can shift into summer mode.

Sioux Lookout Weather Fun Fact

Did you know? Sioux Lookout’s surrounding boreal forests can intensify the feeling of heat due to lower wind flow and added humidity from the lakes and rivers. This “forest sauna” effect can make 29°C feel a few degrees warmer—so if you’re feeling the sizzle, you’re not imagining it.