Sarnia weather and climate in 2025
Day
28 °C
Night
17 °C
Sea
21 °C
Precipitation
74 mm
in month
Rainy days
10 days
in month
Daylight
15 hours
average
Sunshine
9 hours
average
Humidity
71 %
Day
28 °C
Night
17 °C
Sea
21 °C
Precipitation
74 mm
in month
Rainy days
10 days
in month
Daylight
15 hours
average
Sunshine
9 hours
average
Humidity
71 %
Overview: Sarnia
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Weather overview for Sarnia
Weather overview
Sarnia, a city located in the province of Ontario, Canada, experiences a range of weather conditions throughout the year. From chilly winters with temperatures often dipping below freezing, to warm summers when the mercury can rise to nearly 30 degrees Celsius, the city enjoys a full four-season climate. Precipitation is distributed throughout the year, but the city is known to have wetter springs and falls, with rainfall peaking in specific months. Snowfall occurs in the winter months, transforming the city into a wintery wonderland, while summers are typically highlighted by pleasant warmth and enjoyable outdoor conditions.
January weather
January in Sarnia brings the depths of winter with icy chills and average high temperatures hovering around -1 °C (31 °F). The long nights see average lows of -8 °C (18 °F), and with 11 days of snow and rainfall, there's a need for warm waterproof clothing.
February weather
As February rolls in, Sarnia sees similar weather conditions with short days and an average high of just 0 °C (32 °F). Nighttime lows of -8 °C (18 °F) are common, making for frigid evenings. With 10 days of snow and rain, it's imperative to remain bundled up.
March weather
March offers a glimmer of hope as winter begins to wane, with average highs reaching 5 °C (41 °F). Nighttime still clings to the cold at an average of -4 °C (25 °F), and with 11 days of precipitation, the weather can be quite unpredictable.
April weather
April showcases spring's arrival with milder days and a notable increase in temperatures, averaging highs of 12 °C (54 °F). Nights are cooler at 2 °C (35 °F), and precipitation remains frequent with 12 days, signaling a time for transitional attire.
May weather
May in Sarnia brings brighter days with an increase in sun hours, and temperatures reach pleasant highs of 19 °C (66 °F). The nights become more comfortable at 7 °C (45 °F), and with an average of 11 days of rain, it's wise to have light rain gear accessible.
June weather
June's summer warmth becomes more apparent as it delivers an average high of 25 °C (76 °F). Nighttimes are balmy with an average low of 13 °C (56 °F), and the rain doesn't let up, featuring 11 days of wet weather, making it ideal for light, airy clothing.
July weather
July is the peak of summer, and Sarnia basks in highs of 28 °C (82 °F) with night temperatures only dropping to around 17 °C (62 °F). Moderate rainfall of 10 days indicates that summer storms are a possibility, so it's good to have versatile clothing.
August weather
Coming into August, Sarnia remains warm with average highs of 27 °C (80 °F). Cooler but mild nights at 16 °C (61 °F) provide relief from the heat. Expect 10 days of rain, meaning summer showers continue to grace the city.
September weather
September sees the start of autumnal shifts, with daytime highs at 23 °C (73 °F) and comfortable night lows of 12 °C (53 °F). Rain stays at the fore with 10 days, accompanied by the dwindling day's sunshine as leaves begin to change.
October weather
October's crisp air is exemplified by a high of 16 °C (61 °F) and a chillier night average of 6 °C (43 °F). With rainfall similar to September at 11 days, the transition to heartier attire becomes evident.
November weather
November's chill further intensifies with an average high of 9 °C (48 °F), and the night time numbers fall to 1 °C (34 °F). Sarnia witnesses 11 days of rainy and snowy conditions, prompting the need for insulating layers.
December weather
December ushers in the official start of winter, with average daytime highs dropping to 2 °C (36 °F) and nights being cold at -4 °C (24 °F). With 12 days of wet weather, the proper gear is essential to handle the coming snowfall.
FAQs
How often does it rain in Sarnia during January?
January typically sees about 11 days of precipitation, with a mix of rain, sleet, and snow, as Sarnia grapples with the cold.
Is February a windy month in Sarnia?
Indeed, February can be quite breezy with winds averaging 4 m/s. It's best to keep windproof gear handy to stay comfortable outdoors.
What can I expect from March's weather in terms of temperature fluctuations in Sarnia?
Temperature swings are common in March, with the thaw setting in and highs reaching 5 °C (41 °F), but be prepared for the cold snap as lows can still dip to -4 °C (25 °F).
Should I expect a lot of rain in April in Sarnia?
April does tend to be wet, with approximately 12 days of rain. Expect to keep your umbrella close by during the spring showers.
How would you describe the weather in May in Sarnia?
May's weather is generally quite accommodating, with a notable warmth during the day and fewer instances of extreme cold at night, prompting the city to come alive with springtime vigor.
Should I expect many hot days in Sarnia during June?
Quite a few days in June will feel hot with daytime highs averaging 25 °C (76 °F)—perfect beach weather, indeed.
Are July's days typically sunny in Sarnia, and what are the sun hours like?
Sunny days are a staple of July, and with an average of 9 a day, there's plenty of sunlight to enjoy outdoor activities to their fullest.
How would you suggest dressing for the temperatures in August in Sarnia?
Lightweight and loose-fitting clothes are the go-to for August's warmth, allowing one to fully enjoy the tail end of summer.
Are September evenings in Sarnia cool enough for a light sweater?
Yes, the evenings are indeed cooling down to 12 °C (53 °F), so a light sweater would be perfect for nighttime outings in September.
How does the October weather in Sarnia affect outdoor recreational activities?
October's chill starts to set in, but it's still quite accommodating for outdoor fun, provided you dress warmly and keep an eye out for rain which occurs for about 11 days.
As winter approaches, how should I prepare for November weather in Sarnia?
Ready your winter wardrobe: heavy coats, scarves, and gloves are advisable as November marks the transition towards colder, wetter weather in Sarnia.
Is December a good time to engage in winter sports in Sarnia?
Yes, with cold temperatures paving the way, December is great for winter sports enthusiasts looking to enjoy activities like skiing and ice skating in Sarnia.
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