Climate averages 1991–2020
Saint John weather
in August.
A mild, moderately wet month: the warmest and the driest of the year.
Long-term climate patterns, not a forecast for a particular trip.
August is a mild month in Saint John: daytime highs average 21.0°C and nights cool to about 14.9°C. By daytime temperature it is the warmest month of the year.
Expect about 80 mm of rain on roughly 9 days, which makes August a moderately wet month (the driest month of the year). Daylight, from sunrise to sunset, lasts about 14 h 06 min on an average August day.
The nearest other city in this atlas is Moncton (134 km away). In August its highs average 23.6°C, 2.6°C warmer than Saint John, with 76 mm of rain.
Among the 86 cities listed in Canada, Saint John ranks joint 83rd of 86 for the warmest August highs and joint 50th of 86 for the driest August (rainfall, lowest first). The mean August high of those 86 cities is 23.8°C; Saint John is 2.8°C cooler than that mean.
From August to September, average highs fall by 3.3°C to 17.8°C, and monthly rainfall rises from 80 mm to 108 mm.
The annual picture
August 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, selected | 21.0°C14.9°C | 14.9°C | 80 | 9.3 | 14.114 h |
| September | 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
August in nearby cities
- Moncton in AugustCanada · 134 kmHigh 23.6°C · Low 15.4°C · 76 mm rain
- Dartmouth in AugustCanada · 206 kmHigh 22.5°C · Low 16.4°C · 91 mm rain
- Halifax in AugustCanada · 207 kmHigh 21.4°C · Low 16.5°C · 91 mm rain
- Québec in AugustCanada · 433 kmHigh 23.2°C · Low 14.7°C · 113 mm rain
- Sherbrooke in AugustCanada · 457 kmHigh 23.1°C · Low 14.8°C · 123 mm rain
- Sydney, Canada in AugustCanada · 466 kmHigh 22.0°C · Low 16.4°C · 89 mm rain
- Lawrence (Massachusetts), United States in AugustUnited States · 498 kmHigh 26.9°C · Low 17.8°C · 84 mm rain
- Manchester, United States in AugustUnited States · 499 kmHigh 26.7°C · Low 16.9°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.