Climate averages 1991–2020
Sarnia weather
in May.
A mild, moderately wet month: the 5th warmest and the joint 10th driest of the year.
Long-term climate patterns, not a forecast for a particular trip.
May is a mild month in Sarnia: daytime highs average 18.3°C and nights cool to about 9.7°C. By daytime temperature it is the 5th warmest of the 12 months.
Expect about 85 mm of rain on roughly 12 days, which makes May a moderately wet month (the joint 10th driest of the 12 months). Daylight, from sunrise to sunset, lasts about 14 h 38 min on an average May day.
The nearest other city in this atlas is Clinton Township (61 km away). In May its highs average 19.5°C, 1.2°C warmer than Sarnia, with 89 mm of rain.
Among the 86 cities listed in Canada, Sarnia ranks joint 22nd of 86 for the warmest May highs and joint 46th of 86 for the driest May (rainfall, lowest first). The mean May high of those 86 cities is 17.0°C; Sarnia is 1.3°C warmer than that mean.
From May to June, average highs rise by 5.4°C to 23.7°C, and monthly rainfall rises from 85 mm to 87 mm.
The annual picture
May in context
Monthly precipitation
Average total · mmAverages from hourly ERA5 reanalysis data. Actual weather varies from year to year. How these numbers are calculated
Every month, side by side
Sarnia climate table
| Month | Average highHigh / low | Average low | Precipitation mm/month | Wet days ≥1 mm/day | Daylight hours/dayDaylight h/day |
|---|---|---|---|---|---|
| January | -1.2°C-7.8°C | -7.8°C | 57 | 9.6 | 9.49 h |
| February | -0.3°C-8.0°C | -8.0°C | 52 | 8.4 | 10.510 h |
| March | 4.6°C-3.7°C | -3.7°C | 57 | 9.6 | 11.912 h |
| April | 11.4°C2.8°C | 2.8°C | 85 | 11.4 | 13.413 h |
| May, selected | 18.3°C9.7°C | 9.7°C | 85 | 12.0 | 14.615 h |
| June | 23.7°C15.9°C | 15.9°C | 87 | 10.7 | 15.315 h |
| July | 26.1°C18.8°C | 18.8°C | 71 | 11.0 | 15.015 h |
| August | 25.2°C18.3°C | 18.3°C | 70 | 10.4 | 13.914 h |
| September | 21.7°C14.7°C | 14.7°C | 73 | 9.1 | 12.513 h |
| October | 14.7°C8.5°C | 8.5°C | 76 | 10.8 | 11.111 h |
| November | 7.7°C2.2°C | 2.2°C | 66 | 9.7 | 9.810 h |
| December | 1.8°C-3.3°C | -3.3°C | 56 | 9.4 | 9.19 h |
Precipitation (rain or snow, as water) is the average of the 30 separate monthly totals. A wet day is a local calendar day with at least 1 mm of precipitation. Daylight is the calculated sunrise-to-sunset length, not measured sunshine.
Compare places
May in nearby cities
- Clinton Township in MayUnited States · 61 kmHigh 19.5°C · Low 10.6°C · 89 mm rain
- Shelby in MayUnited States · 62 kmHigh 19.6°C · Low 10.2°C · 93 mm rain
- Sterling Heights in MayUnited States · 68 kmHigh 19.7°C · Low 10.5°C · 89 mm rain
- Rochester Hills in MayUnited States · 70 kmHigh 19.5°C · Low 9.9°C · 98 mm rain
- Warren in MayUnited States · 74 kmHigh 19.7°C · Low 10.2°C · 89 mm rain
- Troy in MayUnited States · 74 kmHigh 19.6°C · Low 10.1°C · 94 mm rain
- Southfield in MayUnited States · 87 kmHigh 19.9°C · Low 10.2°C · 94 mm rain
- Waterford in MayUnited States · 88 kmHigh 19.6°C · Low 9.6°C · 94 mm rain
Read the numbers correctly
Climate, not a promise.
These patterns help compare months. They cannot tell you the weather on a specific day of your trip.
Sources, method and limitsHow these numbers are made (what the highs, lows and rain days mean, the sources and the model cell used for Sarnia) is explained once on the Sarnia year overview and on the Sources, method and limits page.