Frequently Asked Questions About London Ontario Weather

London receives an average of 194 centimeters of snow per year, distributed primarily between November and March. January is typically the snowiest month with approximately 50 centimeters, followed by December and February with 40-45 centimeters each. The city experiences measurable snowfall on roughly 55-60 days annually. Snow cover usually persists from late December through mid-March, though early season snow in November often melts quickly. The record single-day snowfall was 47 centimeters on February 4, 2007. This snowfall total is significantly higher than Toronto's 133 centimeters but lower than cities experiencing heavy lake effect like Buffalo at 240 centimeters.

September offers the most consistently pleasant weather for visiting London Ontario. Average high temperatures around 21.5°C remain comfortable for outdoor activities without the intense heat and humidity of July and August. Rainfall averages 95 millimeters, slightly higher than summer months, but precipitation typically comes in brief showers rather than prolonged periods. The fall foliage begins showing color, creating scenic conditions throughout the city's parks and along the Thames River. Mosquito activity decreases significantly compared to summer months. Additionally, September avoids the unpredictable conditions of spring when temperatures can swing dramatically, and obviously avoids winter's cold and snow. June and early July also provide excellent conditions if you prefer warmer temperatures.

Yes, London sits within a moderate tornado risk zone in southwestern Ontario. The region experiences 1-2 tornadoes annually within a 100-kilometer radius, though most are weak EF0 or EF1 tornadoes causing minimal damage. The most significant tornado in London's history occurred on April 11, 1965, when an F4 tornado carved a 10-kilometer damage path through the city, causing extensive destruction. Tornado season runs primarily from May through September, with peak activity in June and July when atmospheric conditions favor severe thunderstorm development. Modern warning systems from Environment Canada provide advance notice when conditions support tornado formation. Residents and visitors should know where to shelter during tornado warnings - typically interior rooms on the lowest floor away from windows.

Winter temperatures in London regularly drop below -10°C, with January averaging -6.3°C overall (daytime highs around -1°C and nighttime lows around -9°C). Cold snaps can push temperatures to -20°C or colder, and with wind chill factors, conditions can feel like -30°C or below. The record low temperature of -32.8°C occurred in January 1994. Temperatures remain below freezing for extended periods from December through February, with occasional brief thaws. Visitors should prepare for genuine winter conditions with appropriate clothing including insulated coats, winter boots, gloves, and hats. Indoor heating is universal and effective, so layering is essential for transitioning between outdoor cold and indoor warmth. Vehicle block heaters and remote starters are common among residents.

September receives the most precipitation with an average of 95 millimeters, though summer months from June through August are nearly as wet with 88-91 millimeters monthly. The distribution of precipitation is relatively even throughout the year, with annual totals reaching 1,011 millimeters. However, the character of rainfall differs seasonally - summer precipitation often arrives as intense afternoon thunderstorms that dump significant rain quickly, while spring and fall bring more steady, prolonged periods of rain. Winter precipitation falls primarily as snow. May through September each average 10-12 days with measurable precipitation. Despite September's higher total, the perception of wetness is often greater during November due to persistent drizzle and gray skies.

Summer humidity in London can be quite high, particularly during July and August when warm air masses from the Gulf of Mexico push northward. Humidex values - which combine temperature and humidity to reflect perceived temperature - frequently reach 35-40 during heat waves, making it feel significantly hotter than the actual air temperature. Dew points often climb into the uncomfortable 18-22°C range during humid periods. The combination of 26-27°C temperatures with high humidity creates conditions that feel like 30-35°C. This humidity supports frequent afternoon thunderstorm development as the atmosphere becomes unstable. Air conditioning is standard in most buildings, vehicles, and hotels. The humidity typically breaks when cold fronts pass through, bringing temporary relief with lower dew points and cooler temperatures.