Climate averages 1991–2020
Saint John weather
in September.
A mild, wet month: the joint 3rd warmest and the joint 6th driest of the year.
Long-term climate patterns, not a forecast for a particular trip.
September is a mild month in Saint John: daytime highs average 17.8°C and nights cool to about 11.8°C. By daytime temperature it is the joint 3rd warmest of the 12 months.
Expect about 108 mm of rain on roughly 10 days, which makes September a wet month (the joint 6th driest of the 12 months). Daylight, from sunrise to sunset, lasts about 12 h 35 min on an average September day.
The nearest other city in this atlas is Moncton (134 km away). In September its highs average 19.4°C, 1.6°C warmer than Saint John, with 93 mm of rain.
Among the 86 cities listed in Canada, Saint John ranks joint 75th of 86 for the warmest September highs and joint 76th of 86 for the driest September (rainfall, lowest first). The mean September high of those 86 cities is 19.8°C; Saint John is 2.0°C cooler than that mean.
From September to October, average highs fall by 5.5°C to 12.3°C, and monthly rainfall rises from 108 mm to 133 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
Saint John climate table
| Month | Average highHigh / low | Average low | Precipitation mm/month | Wet days ≥1 mm/day | Daylight hours/dayDaylight h/day |
|---|---|---|---|---|---|
| January | -2.6°C-10.2°C | -10.2°C | 112 | 11.6 | 9.29 h |
| February | -1.7°C-9.1°C | -9.1°C | 96 | 10.3 | 10.410 h |
| March | 1.9°C-4.9°C | -4.9°C | 112 | 11.4 | 11.912 h |
| April | 7.4°C0.7°C | 0.7°C | 105 | 12.3 | 13.513 h |
| May | 13.4°C6.1°C | 6.1°C | 104 | 12.3 | 14.815 h |
| June | 17.8°C11.0°C | 11.0°C | 108 | 12.1 | 15.616 h |
| July | 20.8°C14.6°C | 14.6°C | 91 | 11.0 | 15.315 h |
| August | 21.0°C14.9°C | 14.9°C | 80 | 9.3 | 14.114 h |
| September, selected | 17.8°C11.8°C | 11.8°C | 108 | 10.0 | 12.613 h |
| October | 12.3°C6.6°C | 6.6°C | 133 | 10.9 | 11.011 h |
| November | 6.7°C1.0°C | 1.0°C | 128 | 11.8 | 9.610 h |
| December | 1.2°C-5.3°C | -5.3°C | 137 | 13.1 | 8.89 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
- Moncton in SeptemberCanada · 134 kmHigh 19.4°C · Low 11.4°C · 93 mm rain
- Dartmouth in SeptemberCanada · 206 kmHigh 19.3°C · Low 13.3°C · 97 mm rain
- Halifax in SeptemberCanada · 207 kmHigh 18.6°C · Low 13.7°C · 97 mm rain
- Québec in SeptemberCanada · 433 kmHigh 18.9°C · Low 10.4°C · 109 mm rain
- Sherbrooke in SeptemberCanada · 457 kmHigh 19.3°C · Low 10.8°C · 106 mm rain
- Sydney, Canada in SeptemberCanada · 466 kmHigh 18.5°C · Low 13.2°C · 104 mm rain
- Lawrence (Massachusetts), United States in SeptemberUnited States · 498 kmHigh 22.7°C · Low 14.0°C · 84 mm rain
- Manchester, United States in SeptemberUnited States · 499 kmHigh 22.3°C · Low 13.0°C · 87 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 Saint John) is explained once on the Saint John year overview and on the Sources, method and limits page.