Ontario's June forecast for 2026 is in and here's what's in store

Ontario's June forecast for 2026 is officially in, and if you were hoping for a smooth, consistently sunny start to the summer season, this latest outlook suggests that things might be a little more complicated on this trip around the sun.

After a spring that's already delivered plenty of back-and-forth weather swings, Ontario has been getting early glimpses of summer-like conditions over the past few weeks, with daytime highs occasionally climbing into the high teens.

However, according to a new long-range weather forecast from the Old Farmer's Almanac, the early warmth isn't expected to settle in just yet. The forecast suggests that June in southern Ontario will kick off on a cooler, unsettled note before gradually shifting into more typical summer conditions as the month progresses.

From June 1 to 8, southern Ontario is expected to see a mix of showers paired with cool temperatures. Conditions are expected to become more active between June 9 and 18, when thunderstorms will roll in alongside warm temperatures, followed again by a brief return to cooler conditions.

A short-lived, calm window is expected between June 19 and 21, with sunny skies but still relatively cool temperatures. Following this break, the final stretch of the month from June 22 to 30 is expected to bring in another round of thunderstorms before transitioning into sunny and hot conditions to close out June.

Overall, the average temperature in June is expected to be 16.5 C, which is approximately 1 C below average. Precipitation totals are expected to reach around 110 mm, roughly 30 mm above the monthly average.

According to the Old Farmer's Almanac, May is also shaping up to be a mixed bag weather-wise. From May 17 to 25, which includes the Victoria Day long weekend, conditions in southern Ontario are expected to be on the cooler side. Showers aren’t out of the question either, which could potentially jeopardize some outdoor plans.

From May 26 to 31, the forecast predicts the return of warmer temperatures along with scattered thunderstorms. Overall, May is expected to run a bit cooler than usual, with an average temperature of 11 C (approximately 1 C below average).

By the final stretch of the month, from May 26 to 31, warmer temperatures are expected to return once again, although they'll likely be joined by scattered thunderstorms.