How extreme does Sarnia's weather get?

The hottest, coldest, wettest and snowiest days Sarnia has recorded — the outer limits of what its weather can do, and how far they sit beyond a normal day.

Based on 50+ years of daily weather observations (1971–present), from the Port Huron station 1 km away. Updated through June 2026 — an all-time extreme only changes when a more extreme day actually occurs, so some dates are old. That is normal, not stale data.

The four kinds of extreme

The hottest, coldest, wettest and snowiest single days Sarnia has recorded — each shown against what a normal day that time of year looks like.

🔥 Hottest day

102°F Jul 31, 1975

That is about 21°F hotter than a normal July afternoon in Sarnia (typical high near 81°F).

The three most extreme on record

1 102°F Jul 31, 1975

2 102°F Jun 25, 1988

3 102°F Aug 8, 2001

❄️ Coldest night

-19°F Jan 19, 1994

About 39°F colder than a normal January night in Sarnia (typical low near 20°F).

The three most extreme on record

1 -19°F Jan 19, 1994

2 -15°F Jan 17, 1982

3 -14°F Jan 7, 2014

🌧️ Most rain in one day

3.97 in Sep 7, 1996

More rain in a single day than Sarnia usually gets in the whole month of September (typical September total about 3.3 in).

The three most extreme on record

1 3.97 in Sep 7, 1996

2 3.72 in Jul 22, 1994

3 3.57 in Jul 16, 2005

⛄ Most snow in one day

13.0 in Jan 22, 2005

Close to a whole typical January's snow in one day (Sarnia averages about 11 in across the month).

The three most extreme on record

1 13.0 in Jan 22, 2005

2 12.0 in Dec 11, 2000

3 12.0 in Nov 26, 2002

How hot and cold it gets, month by month

The shaded band is the normal range of daily temperatures for each month. The dots show the most extreme it has ever been — so you can see how far beyond a normal day the records really sit.

normal range of daily temperatureshottest ever recordedcoldest ever recorded

Sarnia's record heat sits well above even a hot day for the season — July's 102°F is about 21°F beyond a normal hot afternoon. Its record cold is just as far below a normal winter night — the dots mark how rare each extreme really is.

In plain terms

In a normal year, Sarnia's warmest days reach the low 80s°F and its coldest nights drop to the low 20s°F. But across the record it has gone as high as 102°F and as low as −19°F. A single day has delivered over 4 inches of rain or close to 13 inches of snow. Those are the outer edges worth knowing if you are moving here, planning a trip, or thinking about a house.

Methodology & sources

Temperature & precipitation — 1991–2020 normals computed from 30 years of daily observations at New Glasgow, a weather station, about 81 km from the city centre. The underlying daily records come from NOAA's global station network.

How we build these numbers →

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