Canada · 1991–2020

Best time to visit
Sarnia.

June leads for comfortable weather in Sarnia: typically 25°C by day, 14.4°C at night, with 92 mm of rain. Based on measured 1991–2020 NOAA station history.

Best comfortJune

Typical high25°C

Typical low14.4°C

Rain in June92 mm

Comfort

June

June · September · August

83climate match

Beach

July

July · August · June

73climate match

Outdoors

May

May · September · October

80climate match

The weakest month is January, scoring 5 against June’s 83 — days reach only -0.2°C, 24° below the 24°C the score treats as ideal.

Month by month

The whole year,
without the guesswork.

The bars show the comfort score. Day and night temperatures come from daily observed highs and lows; rain is the historical monthly estimate.

Jan

5-0.2° / -7.6°

Feb

51° / -7.1°

Mar

56° / -2.8°

Apr

2812.8° / 2.7°

May

6119.7° / 8.9°

Jun

8325° / 14.4°

Jul

7127.6° / 17.8°

Aug

7526.8° / 17.3°

Sep

8223.2° / 13.3°

Oct

4816.2° / 7.1°

Nov

148.6° / 1.2°

Dec

52.7° / -3.7°

Monthly climate evidence for Sarnia — daylight is calculated from latitude, everything else is measured, sea temperature from the nearest open water 16 km away
Month	Day	Night	Rain	Wet days	Sea	Daylight	Comfort	Coverage
January	-0.2°C	-7.6°C	62 mm	9.9	2.0°C	9 h 20	5	Strong coverage
February	1°C	-7.1°C	52 mm	7.4	0.8°C	10 h 27	5	Strong coverage
March	6°C	-2.8°C	56 mm	8.1	1.1°C	11 h 47	5	Strong coverage
April	12.8°C	2.7°C	80 mm	10.1	3.0°C	13 h 20	28	Strong coverage
May	19.7°C	8.9°C	87 mm	10.2	6.9°C	14 h 37	61	Strong coverage
June	25°C	14.4°C	92 mm	8.7	14.1°C	15 h 20	83	Strong coverage
July	27.6°C	17.8°C	84 mm	8.6	20.0°C	15 h 03	71	Strong coverage
August	26.8°C	17.3°C	80 mm	8.5	21.5°C	13 h 56	75	Strong coverage
September	23.2°C	13.3°C	84 mm	8.4	19.5°C	12 h 26	82	Strong coverage
October	16.2°C	7.1°C	79 mm	9.7	14.3°C	10 h 58	48	Strong coverage
November	8.6°C	1.2°C	72 mm	9.1	9.2°C	9 h 40	14	Strong coverage
December	2.7°C	-3.7°C	59 mm	8.5	5.2°C	9 h 01	5	Strong coverage

What has changed

Sarnia runs +0.6°C
on the 1961–1990 baseline.

Each bar compares the 2011–2025 daytime average for that month against the same month in 1961–1990, measured at the same station. Months where the older record is too thin to compare are left blank.

Jan

+1.2

Feb

+1.1

Mar

+0.8

Apr

-0.1

May

+0.6

Jun

0.0

Jul

+0.2

Aug

-0.2

Sep

+0.4

Oct

+0.7

Nov

+0.2

Dec

+2.1

June daytime highs, 2011–2025. Last recorded: 24.6°C.

Records at PORT HURON, 1933–2026
Month	Record high	Record low	Wettest day	Wettest / driest month	Years
January	17.8°C26 Jan 1950	-28.3°C19 Jan 1994	66 mm11 Jan 2020	128 mm2005 · driest 5 mm in 1961	90
February	20.6°C26 Feb 2000	-26.1°C9 Feb 1934	46 mm11 Feb 2009	142 mm1950 · driest 3 mm in 1969	90
March	27.8°C21 Mar 2012	-21.7°C2 Mar 2003	52 mm26 Mar 2021	146 mm2016 · driest 6 mm in 1958	92
April	30.6°C13 Apr 1941	-13.3°C3 Apr 1954	59 mm2 Apr 2025	182 mm2013 · driest 25 mm in 1942	90
May	35.6°C29 May 2006	-6.1°C10 May 1941	86 mm11 May 1943	211 mm1943 · driest 7 mm in 1954	92
June	38.9°C25 Jun 1988	0.0°C5 Jun 1945	76 mm2 Jun 1951	190 mm1962 · driest 20 mm in 1965	92
July	39.4°C9 Jul 1936	1.7°C1 Jul 1936	95 mm22 Jul 1994	182 mm2023 · driest 24 mm in 1962	91
August	38.9°C8 Aug 2001	2.8°C25 Aug 1942	77 mm4 Aug 1940	270 mm1956 · driest 13 mm in 2002	92
September	38.3°C2 Sep 1953	-3.9°C29 Sep 1942	101 mm7 Sep 1996	255 mm1996 · driest 12 mm in 1969	91
October	32.2°C5 Oct 1951	-6.7°C27 Oct 1976	73 mm5 Oct 1995	169 mm1954 · driest 12 mm in 1963	92
November	27.2°C1 Nov 1950	-16.7°C24 Nov 1950	78 mm25 Nov 1950	217 mm1950 · driest 14 mm in 1980	92
December	18.9°C24 Dec 2015	-21.7°C23 Dec 1989	51 mm25 Dec 1965	135 mm1957 · driest 8 mm in 1958	90

Typical days per month at PORT HURON, 1991–2020
Month	Days 25°C+	Days 30°C+	Frost nights	Heavy rain (10 mm+)	Snow days
January	0	0	27	2	7
February	0	0	26	2	6
March	<1	0	23	2	3
April	1	0	7	3	<1
May	7	2	<1	3	0
June	16	5	0	3	0
July	24	9	0	2	0
August	22	7	0	3	0
September	11	2	0	3	0
October	2	<1	1	3	0
November	0	0	12	2	<1
December	0	0	24	2	4

The best month has moved. On the 1961–1990 numbers the strongest month here was June (scoring 87); on 2011–2025 it is September (91). Both are scored the same way, from the same station — only the climate underneath changed.

How often, not how much — every day in PORT HURON’s record sorted by what it was actually like, rather than averaged
Month	Warm & dry days	Wet days	Washouts	Week with 3+ wet days	Daytime mean has ranged
January	0%	27%	4%	29%	-3.7–2.7°C
February	0%	24%	5%	24%	-1.9–4.0°C
March	3%	25%	6%	28%	2.7–9.2°C
April	12%	32%	9%	39%	10.0–15.9°C
May	36%	29%	8%	34%	16.5–22.7°C
June	60%	29%	10%	33%	22.9–27.1°C
July	72%	26%	8%	27%	26.1–29.2°C
August	73%	26%	9%	26%	25.1–28.7°C
September	57%	26%	8%	31%	21.2–25.0°C
October	23%	27%	8%	31%	14.1–19.1°C
November	2%	28%	7%	32%	6.4–11.1°C
December	0%	27%	5%	29%	-0.9–4.8°C

A warm and dry day reaches 20°C with under 1 mm of rain; a wet day gets 1 mm or more; a washout gets 10 mm or more. The week column is the share of seven-day stretches in that month, across the station’s whole daily record, that contained three or more wet days — the odds a week-long trip is rained on repeatedly, counted rather than modelled. The last column is the 10th to 90th percentile of that month’s daytime average across individual years: a narrow band means the average is what you will get, a wide one means the average is a midpoint between years that felt quite different.

1934Each stripe is one year’s mean temperature against the 82-year average. Warmest: 2016. Coolest: 1972.2025

The evidence behind this page

Nearby, measured,
and named.

Place identity: GeoNames 6141190
NOAA station: USC00206680 · PORT HURON
Station distance: 1.3 km from the place centre
Climate period: 1991–2020
Minimum month coverage: 29 usable years
Daylight: Calculated from latitude 42.98°, mid-month, sunrise to sunset including refraction. Not a station measurement.
Sea temperature: NOAA OISST v2.1 1991–2020 monthly climatology, nearest open water 16 km from the place centre. A sheltered bay can run warmer than the open sea it is measured from.
Important limit: Historical climate is not a forecast. Nearby stations can miss mountains, coasts, and local microclimates.

These places read the same station, so their numbers are identical — distance from PORT HURON is what differs

Port Huron→Marysville→Corunna→Saint Clair→Abbottsford→Atkins→

Or put two places side by side: Sarnia vs Port Huron

Best time to visitSarnia.

June

July

May

The whole year,without the guesswork.

Sarnia runs +0.6°Con the 1961–1990 baseline.

Nearby, measured,and named.

Best time to visit
Sarnia.

The whole year,
without the guesswork.

Sarnia runs +0.6°C
on the 1961–1990 baseline.

Nearby, measured,
and named.