Sarnia weather in October

In October, Sarnia sees average daytime highs of 15°C and overnight lows near 8°C, with 77 mm of precipitation across 10.8 wet days and about 10.8 hours of daylight. It is the 6th-warmest and 4th-wettest month of the year here.

Highs ease over the month, from about 18°C in the first days to 11°C by the end. The sky is clear or mostly clear about 26% of the time in October, and the air most often feels dry.

Daylight stretches from about 11 h 30 min at the start of October to 10 h 06 min by month's end. Set against the rest of the year, October is Sarnia's 6th-clearest and 4th-windiest month. For the whole year in context, see Sarnia's year-round climate.

Daytime high
15°
6th warmest
Overnight low
7th coldest
Precipitation
77 mm
10.8 wet days
Daylight
10 h 48 min
6:51 AM – 5:39 PM
Cloud cover
63%
6th clearest
Wind
15 km/h
4th windiest
Solar energy
2.81 kWh/m²
Travel score
4.3
out of 10

Sarnia is city in Ontario, Canada.

Air quality
Good
PM2.5 7 µg/m³ · 2019
Density
440/km²
people per km²
Founded
1830

Air quality: WHO Ambient Air Quality Database. Density & description: Wikidata (CC0), GeoNames.

Temperature in October

Average highAverage lowShaded bands: 10–90% of days

Highs ease over the month, from about 18°C in the first days to 11°C by the end.

A typical October day in Sarnia reaches about 15°C in the afternoon and slips back to 8°C overnight — a 7°C spread between the day's warmth and the night's chill. On most days the high lands between 9°C and 20°C. Set against its neighbours, October runs about 7°C cooler than September and about 7°C warmer than November.

10°15°20°25°151015202531
Avg high (°C)Avg low (°C)
11810
21810
31810
41710
51710
6179
7179
8179
9169
10169
11169
12168
13158
14158
15158
16158
17147
18147
19147
20147
21137
22137
23136
24136
25126
26126
27126
28125
29115
30115
31115

How October really feels in Sarnia

Once humidity and wind are folded in, October averages 0 days that feel above 32°C and 0 that feel at or below 0°C — the comfort signal a plain temperature reading hides.

Days feeling ≥ 32°C
0
heat index over the day's high
Days feeling ≤ C
0
wind chill below the day's low

October sits comfortably in between — no days that feel dangerously hot or drop to a hard freeze once humidity and wind are folded in.

Sarnia weather by month

How October compares with the rest of the year at a glance. October is the 6th-warmest and 4th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysSnow daysDaylight (hours)Travel score
Jan-1° / -7°579.67.39.20.0
Feb / -7°518.46.310.20.0
Mar / -3°579.64.611.60.3
Apr11° / 8511.41.813.12.7
May18° / 10°8512014.45.4
Jun24° / 16°8710.8015.16.7
Jul26° / 18°7111014.86.6
Aug25° / 18°7010.4013.86.9
Sep21° / 14°739.1012.36.7
Oct15° / 7710.80.110.84.3
Nov / 669.72.49.51.2
Dec / -3°569.45.68.90.0

Cloud cover in October

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 26% of the time in October.

Beyond those clear spells, partly cloudy skies cover about 15% of October, with mostly cloudy or overcast conditions the remaining 59%. Skies tend to cloud over as the month goes on.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
14852
24852
34852
44951
54852
64852
74852
84753
94753
104852
114753
124654
134555
144456
154357
164258
174159
183961
193862
203763
213664
223565
233466
243466
253367
263268
273268
283169
293169
303169
313070

Chance of precipitation in October

Any precipitation

Sarnia gets around 77 mm of rain and snow over 10.8 wet days in October. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable precipitation averages around 34% and peaks near 36% on the wettest days, and about 0 day brings snow.

0%10%20%30%40%50%151015202531
Rain chance (%)
135
235
335
434
534
634
733
833
933
1032
1132
1232
1332
1432
1533
1633
1734
1835
1935
2036
2136
2236
2336
2436
2536
2636
2736
2836
2935
3034
3134

Humidity in October

DryComfortableHumidMuggyOppressiveMiserable

Most of October feels dry — the stacked bands show each day's mix of comfort levels, read off the dew point.

By dew point, October lands in the dry band about 89% of days. It rarely turns muggy — the humid and sticky bands barely register.

0%25%50%75%100%151015202531
Dry (%)Comfortable (%)Humid (%)Muggy (%)
1731773
2761662
3771562
4781462
5801352
6821251
7821251
8841141
9851041
1086941
1186941
1288831
1389731
1490721
1591720
1692620
1793610
1893610
1993610
2094510
2194510
2294510
2395410
2496400
2596400
2697300
2797300
2897300
2997300
3097300
3198200

Wind in October

Winds average 15 km/h in October.

Across October, daily wind ranges from about 14 km/h on the calmest days to 16 km/h at its breeziest. It stays fairly steady from day to day.

05101520151015202531
Wind speed (km/h)Feels
114light breeze
214light breeze
314light breeze
415light breeze
515light breeze
615light breeze
715light breeze
815light breeze
915light breeze
1015light breeze
1115light breeze
1215light breeze
1315light breeze
1415light breeze
1515light breeze
1615light breeze
1715light breeze
1816light breeze
1916light breeze
2016light breeze
2116light breeze
2216light breeze
2316light breeze
2416light breeze
2516light breeze
2616light breeze
2716light breeze
2816light breeze
2916light breeze
3016light breeze
3116light breeze

Sunrise & sunset in October

DaylightNight

Daylight runs from about 11 h 30 min at the start of October to 10 h 06 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 84 minutes over October. Sunrise moves from 6:32 AM to 7:10 AM, and sunset from 6:05 PM to 5:17 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
111.56:326:05
211.56:346:03
311.46:356:01
411.46:365:59
511.36:375:58
611.36:385:56
711.26:405:54
811.26:415:52
911.16:425:51
1011.16:435:49
1111.06:445:47
1211.06:465:45
1310.96:475:44
1410.96:485:42
1510.96:495:40
1610.86:515:39
1710.86:525:37
1810.76:535:36
1910.76:545:34
2010.66:565:32
2110.66:575:31
2210.56:585:29
2310.56:595:28
2410.47:015:26
2510.47:025:25
2610.37:035:24
2710.37:045:22
2810.27:065:21
2910.27:075:19
3010.27:085:18
3110.17:105:17

Solar energy in October

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in October, about 2.81 kWh/m².

For context, solar energy here swings from a low near 1.36 kWh/m² to a high of 6.37 kWh/m² in June across the year — October's 2.81 kWh/m² falls in the middle.

01234151015202531
Solar energy (kWh/m²)Level
13.5Moderate
23.5Moderate
33.5Moderate
43.4Moderate
53.4Moderate
63.3Moderate
73.3Moderate
83.2Moderate
93.2Moderate
103.1Moderate
113.1Moderate
123.0Moderate
133.0Moderate
142.9Moderate
152.9Moderate
162.8Moderate
172.8Moderate
182.7Moderate
192.7Moderate
202.6Moderate
212.5Moderate
222.5Moderate
232.5Moderate
242.4Moderate
252.4Moderate
262.3Moderate
272.3Moderate
282.3Moderate
292.2Moderate
302.2Moderate
312.2Moderate
Planning a trip in October

Is October a good time to visit Sarnia?

Our two travel scores rate October for general sightseeing and for beach or pool weather — 0 (poor) to 10 (ideal).

4.3
Sightseeing
6th-best month of the year
0.5
Beach & pool
6th-best month of the year

October is a reasonable time to visit Sarnia for sightseeing.

What to pack for Sarnia in October

From October's temperature range, rain chance, sun and wind — what's worth putting in the bag.

In October, Sarnia sees daytime highs around 15°C and nights near 8°C. Worth packing: a warm layer and rain gear. About 11 days see rain.

a warm layerrain gear

Sea temperature near Sarnia in October

The nearest coast averages about 14°C in October — the other half of the beach question. The full-year curve and swim-comfort zones are below.

The sea at the nearest coast (about 16 km away) is warmest in August at about 22°C and coldest in February near 1°C.

It's comfortable for a long swim from Jul 19 to Sep 8 — about 1.7 months when the water holds above 20°C.

0°10°20°JanFebMarAprMayJunJulAugSepOctNovDecbracingcoolrefreshingwarmcomfortable to swim
Sea temperature (°C)Comfort
Jan2Bracing
Feb1Bracing
Mar1Bracing
Apr3Bracing
May7Bracing
Jun14Bracing
Jul20Refreshing
Aug22Refreshing
Sep20Cool
Oct14Bracing
Nov9Bracing
Dec5Bracing

UV index in Sarnia in October

LowModerateHighVery highExtreme

Clear-sky midday UV in October peaks around 3 — enough to warrant sun protection. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Sarnia peaks around June 20 at about 9 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near December 20 at about 1 (low).

The index reaches 3 or more — the level where the WHO recommends sun protection — in 8 months of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecLowModerateHighVery highHighModerateLowJun 20UV 9Dec 20UV 1
UV index (midday)Level
Jan2Low
Feb2Moderate
Mar4Moderate
Apr5High
May7High
Jun9Very high
Jul8Very high
Aug7High
Sep6High
Oct3Moderate
Nov2Moderate
Dec1Low
Location & terrain

Where is Sarnia?

Sarnia sits at 43.0°N, 82.4°W, 185 m above sea level, in Canada. The nearest listed city is Port Huron, 2.0 km away.

Topography around Sarnia

How much the land rises and falls, and what covers it, within 3, 16 and 80 km of Sarnia.

Within 3 km, the terrain around Sarnia has only modest variations in elevation — a maximum elevation change of 19 m around an average of 182 m above sea level; within 16 km, only modest variations in elevation — a maximum elevation change of 69 m; within 80 km, only modest variations in elevation — a maximum elevation change of 216 m.

The land around Sarnia is covered by artificial surfaces (52%) and trees (22%) within 3 km, cropland (27%), trees (25%) and water (24%) within 16 km, and cropland (45%) and water (25%) within 80 km.

3 km
19 m
16 km
69 m
80 km
216 m
treesgrasslandcroplandartificial surfacesbare terrainwaterwetland
October weather nearby: Port Huron 2.0 km · Mount Clemens 57 km · Clinton Township 61 km · Shelby 62 km · Strathroy 64 km · Chatham 65 km · Saint Clair Shores 67 km · Sterling Heights 68 km

Canada travel facts

Travel advisory
Level 1
Exercise Normal Precautions
Power plugs
Type A / B
120 V · 60 Hz
Prices
≈ 83% of US
price level, 2025
GDP per capita
$55,698
2025
Happiness
6.7 / 10
World Happiness, 2025
Safe drinking water
97%
of population, 2024
Homicide rate
2
per 100k, 2023
Road deaths
5.3
per 100k/yr, 2019
Income group
High
World Bank
Religion
Christian 53%none 35%Muslim 5%Hindu 2%

Sources: World Bank, US State Department, World Happiness Report, WHO/UNICEF, EF EPI, CIA World Factbook.

Data sources

Temperature, precipitation, cloud, humidity, wind and solar figures are a 1991–2020 climatology for Sarnia (42.9787°, -82.4041°, elevation 185 m), computed from hourly ERA5 reanalysis — contains modified Copernicus Climate Change Service information. Sun figures are astronomical calculations, not observations. City data © GeoNames, CC BY 4.0. Map outlines from Natural Earth (public domain); interactive map © Google. Sea temperatures are the NOAA OISST v2.1 1991–2020 monthly climatology (public domain), sampled at the nearest ocean point. UV index is derived from CAMS (Copernicus Atmosphere Monitoring Service) clear-sky UV data — contains modified Copernicus Atmosphere Monitoring Service information. Topography is sampled from the Copernicus DEM GLO-90 elevation model (© ESA/Airbus) and ESA WorldCover 2021 land cover (CC BY 4.0).