Climate averages 1991–2020
Dartmouth weather
in September.
A mild, wet month: the 3rd warmest and the 5th driest of the year.
Long-term climate patterns, not a forecast for a particular trip.
September is a mild month in Dartmouth: daytime highs average 19.3°C and nights cool to about 13.3°C. By daytime temperature it is the 3rd warmest of the 12 months.
Expect about 97 mm of rain on roughly 9 days, which makes September a wet month (the 5th driest of the 12 months). Daylight, from sunrise to sunset, lasts about 12 h 34 min on an average September day.
The nearest other city in this atlas is Halifax (3 km away). In September its highs average 18.6°C, 0.7°C cooler than Dartmouth, with 97 mm of rain.
Among the 86 cities listed in Canada, Dartmouth ranks joint 59th of 86 for the warmest September highs and joint 65th of 86 for the driest September (rainfall, lowest first). The mean September high of those 86 cities is 19.8°C; Dartmouth is 0.5°C cooler than that mean.
From September to October, average highs fall by 5.8°C to 13.5°C, and monthly rainfall rises from 97 mm to 124 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
Dartmouth climate table
| Month | Average highHigh / low | Average low | Precipitation mm/month | Wet days ≥1 mm/day | Daylight hours/dayDaylight h/day |
|---|---|---|---|---|---|
| January | -0.5°C-7.9°C | -7.9°C | 111 | 11.5 | 9.29 h |
| February | -0.1°C-7.7°C | -7.7°C | 101 | 10.5 | 10.410 h |
| March | 3.0°C-4.0°C | -4.0°C | 108 | 12.0 | 11.912 h |
| April | 8.1°C1.1°C | 1.1°C | 92 | 12.1 | 13.413 h |
| May | 13.6°C6.0°C | 6.0°C | 83 | 11.2 | 14.815 h |
| June | 18.4°C11.2°C | 11.2°C | 98 | 11.7 | 15.516 h |
| July | 22.2°C15.8°C | 15.8°C | 90 | 10.3 | 15.215 h |
| August | 22.5°C16.4°C | 16.4°C | 91 | 10.2 | 14.114 h |
| September, selected | 19.3°C13.3°C | 13.3°C | 97 | 9.4 | 12.613 h |
| October | 13.5°C8.0°C | 8.0°C | 124 | 10.6 | 11.011 h |
| November | 7.9°C2.6°C | 2.6°C | 129 | 11.1 | 9.610 h |
| December | 2.9°C-3.0°C | -3.0°C | 134 | 13.3 | 8.99 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
- Halifax in SeptemberCanada · 3 kmHigh 18.6°C · Low 13.7°C · 97 mm rain
- Moncton in SeptemberCanada · 185 kmHigh 19.4°C · Low 11.4°C · 93 mm rain
- Saint John in SeptemberCanada · 206 kmHigh 17.8°C · Low 11.8°C · 108 mm rain
- Sydney, Canada in SeptemberCanada · 311 kmHigh 18.5°C · Low 13.2°C · 104 mm rain
- Québec in SeptemberCanada · 638 kmHigh 18.9°C · Low 10.4°C · 109 mm rain
- Lynn in SeptemberUnited States · 642 kmHigh 21.0°C · Low 14.8°C · 87 mm rain
- Lawrence (Massachusetts), United States in SeptemberUnited States · 648 kmHigh 22.7°C · Low 14.0°C · 84 mm rain
- Boston in SeptemberUnited States · 656 kmHigh 22.4°C · Low 14.1°C · 88 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 Dartmouth) is explained once on the Dartmouth year overview and on the Sources, method and limits page.
Halifax lies in the same rainfall cell, so its rainfall figures are identical to these; temperatures differ because they come from smaller 0.1° cells.