ClimateAverages

Sarnia Climate

Ontario, Canada · population 82,998 · 445 weather stations within 200 km · records 1750 to 2025

Average annual daytime high
13.3°C
Warmest month · July
27.1°C
Typical daytime high
Coldest month · January
-9.1°C
Typical overnight low

Sarnia has an average annual daytime high of 13.3°C, based on the 1951 to 1980 baseline. Its warmest month is July, when highs typically reach 27.1°C, and its coldest is January, with overnight lows near -9.1°C.

Month by month averages

MonthAvg highAvg low
January-1.5°C-9.1°CColdest
February-0.2°C-8.5°C
March4.8°C-3.9°C
April12.8°C1.8°C
May19.4°C7.4°C
June24.7°C12.8°C
July27.1°C15.4°CWarmest
August26.2°C14.9°C
September22.3°C11.1°C
October15.7°C5.3°C
November7.8°C0.1°C
December1.0°C-5.8°C

Temperature range across the year

-11°-1°9°19°29°JanFebMarAprMayJunJulAugSepOctNovDec
Daytime high Overnight low
Hottest year on record
2011
+2.7°C vs. 1951–1980
Coldest year on record
1836
-2.7°C vs. 1951–1980

These figures reflect annual averages, not single-day records. Daily observations are outside this dataset's precision.

Is Sarnia getting hotter?

Since 1900, Sarnia's average temperature has risen by +2.2°C. Compared to the earliest station records that begin in 1750, warming totals +3.0°C.

7.7°8.4°9.0°9.7°10.4°1951–1980 baseline190019251950197520002025

20-year smoothed annual temperature reconstructed from station anomalies. Dashed line: 1951–1980 baseline.

Best time to visit
May to October

Daytime highs sit within a comfortable 15°C to 26°C range.

FAQ

What is the average temperature in Sarnia?

Sarnia's average annual daytime high is 13.3°C, based on the 1951 to 1980 baseline period. The warmest month is July, with highs averaging 27.1°C, and the coldest is January, with lows averaging -9.1°C.

What is the warmest month in Sarnia?

July is the warmest month in Sarnia, with typical daytime highs of 27.1°C.

What is the hottest year on record for Sarnia?

2011 is the hottest year on record for Sarnia, running +2.7°C above the 1951 to 1980 baseline.

Is Sarnia getting hotter?

Yes. Since 1900, Sarnia has warmed by roughly +2.2°C.

When is the best time to visit Sarnia?

May to October typically offers the most comfortable daytime highs, in the 15°C to 26°C range.

Nearby cities

Baseline period 1951 to 1980. Monthly averages are the mean of station observations weighted by proximity. Warming trend is the 20-year smoothed anomaly against that baseline.