Sarnia weather
Best months for weather: May–Sep. Below: today's sky, the hour-by-hour rain chance and the 16-day forecast for Sarnia, Ontario, Canada.
Best Time to Visit
Peak season May–SepOff season Nov–Mar
Sarnia weather by month
When is the best time to visit Sarnia?
Based on weather alone, the best time to visit Sarnia is May–Sep, according to NASA's 2001–2025 climate averages. Nov–Mar tends to be the least pleasant. Average highs run from -1°C (29°F) in January to 26°C (79°F) in July.
What is the rainiest month in Sarnia?
May is the wettest month, with about 85 mm (3.3 in) of rain on average. February is the driest, with about 52 mm (2.0 in).
What is the hottest month in Sarnia?
July is the warmest, with average highs of 26°C (79°F) and lows of 17°C (63°F). January is the coolest, with highs of -1°C (29°F) and lows of -8°C (17°F).
Does Sarnia have a rainy season?
Not a strong one. No month averages more than 150 mm of rain; the wettest is May at about 85 mm (3.3 in).
Sources: 2001–2025 monthly averages from NASA POWER (MERRA-2 reanalysis), forecast and current conditions from Open-Meteo. Page updated . How we rate months