Climate averages 1991–2020
St. John's weather
in September.
A mild, wet month: the 3rd warmest and the 6th driest of the year.
Long-term climate patterns, not a forecast for a particular trip.
September is a mild month in St. John's: daytime highs average 16.3°C and nights cool to about 10.7°C. By daytime temperature it is the 3rd warmest of the 12 months.
Expect about 93 mm of rain on roughly 11 days, which makes September a wet month (the 6th driest of the 12 months). Daylight, from sunrise to sunset, lasts about 12 h 37 min on an average September day.
The nearest other city in this atlas is Sydney, Canada (590 km away). In September its highs average 18.5°C, 2.2°C warmer than St. John's, with 104 mm of rain.
Among the 86 cities listed in Canada, St. John's ranks 84th of 86 for the warmest September highs and joint 56th of 86 for the driest September (rainfall, lowest first). The mean September high of those 86 cities is 19.8°C; St. John's is 3.5°C cooler than that mean.
From September to October, average highs fall by 5.2°C to 11.1°C, and monthly rainfall rises from 93 mm to 105 mm.
The annual picture
September 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
St. John's climate table
| Month | Average highHigh / low | Average low | Precipitation mm/month | Wet days ≥1 mm/day | Daylight hours/dayDaylight h/day |
|---|---|---|---|---|---|
| January | -0.1°C-5.8°C | -5.8°C | 124 | 14.4 | 8.99 h |
| February | -0.5°C-6.4°C | -6.4°C | 103 | 12.9 | 10.210 h |
| March | 1.1°C-4.3°C | -4.3°C | 105 | 12.8 | 11.912 h |
| April | 4.7°C-0.6°C | -0.6°C | 87 | 12.2 | 13.614 h |
| May | 9.1°C2.6°C | 2.6°C | 72 | 11.1 | 15.115 h |
| June | 13.7°C7.0°C | 7.0°C | 66 | 10.6 | 15.916 h |
| July | 18.9°C12.2°C | 12.2°C | 78 | 10.5 | 15.616 h |
| August | 19.6°C13.7°C | 13.7°C | 80 | 10.4 | 14.314 h |
| September, selected | 16.3°C10.7°C | 10.7°C | 93 | 10.7 | 12.613 h |
| October | 11.1°C6.5°C | 6.5°C | 105 | 12.5 | 10.911 h |
| November | 6.8°C2.3°C | 2.3°C | 110 | 13.6 | 9.49 h |
| December | 2.5°C-2.0°C | -2.0°C | 127 | 15.3 | 8.59 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
September in nearby cities
- Sydney, Canada in SeptemberCanada · 590 kmHigh 18.5°C · Low 13.2°C · 104 mm rain
- Dartmouth in SeptemberCanada · 896 kmHigh 19.3°C · Low 13.3°C · 97 mm rain
- Halifax in SeptemberCanada · 898 kmHigh 18.6°C · Low 13.7°C · 97 mm rain
- Moncton in SeptemberCanada · 933 kmHigh 19.4°C · Low 11.4°C · 93 mm rain
- Saint John in SeptemberCanada · 1053 kmHigh 17.8°C · Low 11.8°C · 108 mm rain
- Saguenay in SeptemberCanada · 1366 kmHigh 17.2°C · Low 8.6°C · 127 mm rain
- Québec in SeptemberCanada · 1398 kmHigh 18.9°C · Low 10.4°C · 109 mm rain
- Sherbrooke in SeptemberCanada · 1485 kmHigh 19.3°C · Low 10.8°C · 106 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 St. John's) is explained once on the St. John's year overview and on the Sources, method and limits page.