Climate averages 1991–2020
Nepean weather
in September.
A mild, wet month: the 4th warmest and the 8th driest of the year.
Long-term climate patterns, not a forecast for a particular trip.
September is a mild month in Nepean: daytime highs average 20.4°C and nights cool to about 11.8°C. By daytime temperature it is the 4th warmest of the 12 months.
Expect about 90 mm of rain on roughly 10 days, which makes September a wet month (the 8th 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 Gloucester, Canada (7 km away). In September its highs average 20.3°C, about as warm as Nepean, with 90 mm of rain.
Among the 86 cities listed in Canada, Nepean ranks joint 31st of 86 for the warmest September highs and joint 51st of 86 for the driest September (rainfall, lowest first). The mean September high of those 86 cities is 19.8°C; Nepean is 0.6°C warmer than that mean.
From September to October, average highs fall by 7.6°C to 12.8°C, and monthly rainfall rises from 90 mm to 97 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
Nepean climate table
| Month | Average highHigh / low | Average low | Precipitation mm/month | Wet days ≥1 mm/day | Daylight hours/dayDaylight h/day |
|---|---|---|---|---|---|
| January | -4.8°C-14.6°C | -14.6°C | 70 | 10.4 | 9.29 h |
| February | -3.0°C-13.4°C | -13.4°C | 57 | 8.9 | 10.410 h |
| March | 2.7°C-7.5°C | -7.5°C | 71 | 10.2 | 11.912 h |
| April | 10.7°C0.3°C | 0.3°C | 92 | 11.3 | 13.513 h |
| May | 18.4°C7.7°C | 7.7°C | 85 | 11.3 | 14.915 h |
| June | 23.3°C13.3°C | 13.3°C | 95 | 11.3 | 15.616 h |
| July | 25.7°C16.3°C | 16.3°C | 94 | 11.7 | 15.315 h |
| August | 24.5°C15.7°C | 15.7°C | 86 | 10.8 | 14.114 h |
| September, selected | 20.4°C11.8°C | 11.8°C | 90 | 9.9 | 12.613 h |
| October | 12.8°C5.4°C | 5.4°C | 97 | 11.7 | 11.011 h |
| November | 5.5°C-1.0°C | -1.0°C | 80 | 11.1 | 9.610 h |
| December | -1.1°C-8.4°C | -8.4°C | 76 | 11.5 | 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
- Gloucester, Canada in SeptemberCanada · 7 kmHigh 20.3°C · Low 11.8°C · 90 mm rain
- Ottawa in SeptemberCanada · 9 kmHigh 20.4°C · Low 12.0°C · 95 mm rain
- Kanata in SeptemberCanada · 16 kmHigh 20.4°C · Low 11.8°C · 87 mm rain
- Gatineau in SeptemberCanada · 16 kmHigh 20.3°C · Low 12.2°C · 95 mm rain
- Orléans, Canada in SeptemberCanada · 22 kmHigh 20.0°C · Low 11.6°C · 96 mm rain
- Kingston, Canada in SeptemberCanada · 137 kmHigh 20.2°C · Low 14.8°C · 95 mm rain
- Pierrefonds-Roxboro in SeptemberCanada · 148 kmHigh 20.4°C · Low 12.6°C · 92 mm rain
- Saint-Louis-de-Terrebonne in SeptemberCanada · 156 kmHigh 20.0°C · Low 11.9°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 Nepean) is explained once on the Nepean year overview and on the Sources, method and limits page.
Gloucester, Canada lies in the same rainfall cell, so its rainfall figures are identical to these; temperatures differ because they come from smaller 0.1° cells.