Climate averages 1991–2020
Meridian weather
in September.
A warm, very dry month: the 4th warmest and the 3rd driest of the year. Meets the pleasant-weather rule
Long-term climate patterns, not a forecast for a particular trip.
September is a warm month in Meridian: daytime highs average 26.1°C and nights cool to about 12.4°C. By daytime temperature it is the 4th warmest of the 12 months.
Expect about 9.8 mm of rain on roughly 2 days, which makes September a very dry month (the 3rd driest of the 12 months). Daylight, from sunrise to sunset, lasts about 12 h 33 min on an average September day.
The nearest other city in this atlas is Boise (15 km away). In September its highs average 26.2°C, about as warm as Meridian, with 10 mm of rain.
Among the 498 cities listed in the United States, Meridian ranks joint 276th of 498 for the warmest September highs and joint 110th of 498 for the driest September (rainfall, lowest first). The mean September high of those 498 cities is 26.9°C; Meridian is 0.8°C cooler than that mean.
From September to October, average highs fall by 8.4°C to 17.6°C, and monthly rainfall rises from 9.8 mm to 20 mm.
The annual picture
September in context
Monthly rainfall
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
Meridian climate table
| Month | Average highHigh / low | Average low | Rainfall mm/month | Rain days ≥1 mm/day | Daylight hours/dayDaylight h/day |
|---|---|---|---|---|---|
| January | 3.8°C-4.3°C | -4.3°C | 40 | 9.0 | 9.39 h |
| February | 7.0°C-2.5°C | -2.5°C | 26 | 7.4 | 10.510 h |
| March | 12.1°C0.8°C | 0.8°C | 31 | 8.6 | 11.912 h |
| April | 16.1°C3.8°C | 3.8°C | 28 | 6.4 | 13.413 h |
| May | 21.8°C8.6°C | 8.6°C | 29 | 5.9 | 14.715 h |
| June | 26.6°C13.1°C | 13.1°C | 16 | 3.4 | 15.415 h |
| July | 32.7°C18.1°C | 18.1°C | 3.4 | 1.0 | 15.115 h |
| August | 31.8°C17.4°C | 17.4°C | 3.4 | 0.9 | 14.014 h |
| September, selected | 26.1°C12.4°C | 12.4°C | 9.8 | 2.0 | 12.613 h |
| October | 17.6°C6.0°C | 6.0°C | 20 | 4.2 | 11.111 h |
| November | 9.3°C0.0°C | 0.0°C | 30 | 7.3 | 9.710 h |
| December | 3.6°C-3.8°C | -3.8°C | 42 | 9.3 | 9.09 h |
Rainfall is the average of the 30 separate monthly totals. A rain 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
- Boise in SeptemberUnited States · 15 kmHigh 26.2°C · Low 12.6°C · 10 mm rain
- Nampa in SeptemberUnited States · 16 kmHigh 26.5°C · Low 13.4°C · 9.8 mm rain
- Kennewick in SeptemberUnited States · 361 kmHigh 27.4°C · Low 13.9°C · 6.9 mm rain
- Tri-Cities in SeptemberUnited States · 367 kmHigh 27.5°C · Low 14.0°C · 6.9 mm rain
- Bend in SeptemberUnited States · 398 kmHigh 22.9°C · Low 7.9°C · 16 mm rain
- Missoula in SeptemberUnited States · 408 kmHigh 22.5°C · Low 9.8°C · 30 mm rain
- Ogden in SeptemberUnited States · 449 kmHigh 24.4°C · Low 11.4°C · 32 mm rain
- Spokane Valley in SeptemberUnited States · 456 kmHigh 23.2°C · Low 10.5°C · 22 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 Meridian) is explained once on the Meridian year overview and on the Sources, method and limits page.
Nampa lies in the same rainfall cell, so its rainfall figures are identical to these; temperatures differ because they come from smaller 0.1° cells.