Olympia weather in September: Olympia, Washington: normal highs, lows, rain and records for September
Olympia in September has a normal high of 72°F and a normal low of 46°F, a daily mean of 59°F, falling from 76°F on the 1st to 67°F by the 30th. Measurable precipitation falls on 8 days in a normal September, 2.04 inches in all. (NOAA 1991-2020 normals)
In metric: a normal high of 22°C and low of 8°C, 52 mm of precipitation in September.
- NOAA stationOlympia Airport
- Station IDUSW00024227
- Location46.97°N 122.90°W
- Elevation188 ft (57 m)
- Population56,271
- Jan 46° 33°
- Feb 49° 32°
- Mar 54° 35°
- Apr 59° 38°
- May 66° 43°
- Jun 71° 47°
- Jul 78° 51°
- Aug 78° 51°
- Sep 72° 46°
- Oct 60° 41°
- Nov 51° 36°
- Dec 45° 33°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
How warm is Olympia in September?
The normal high is 72°F and the normal low 46°F, for a daily mean of 59.1°F. September is 5.1°F cooler than August and 8.8°F warmer than October. September is the 3rd warmest month of the year in Olympia and the 9th wettest. Across the month the normal high falls 9°F, from 76°F on September 1 to 67°F on September 30. From one year to the next September's mean temperature typically moves about 1.7°F either way (NOAA's standard deviation), so roughly two Septembers in three average between 57°F and 61°F.
Bars above: each day's normal high to low. Columns below: the chance of 0.01 inch or more of precipitation that day, on a scale of 0 to 100% (highest 36%).
| Day | High | Low | Chance of 0.01 in | Chance of 0.10 in |
|---|---|---|---|---|
| September 1 | 76°F | 49°F | 22% | 12% |
| September 8 | 75°F | 48°F | 24% | 14% |
| September 15 | 73°F | 46°F | 28% | 16% |
| September 22 | 70°F | 45°F | 31% | 19% |
| September 30 | 67°F | 44°F | 36% | 22% |
Every day of September: normal high, low and chance of precipitation (warmest afternoon September 1, coldest night September 30)
| Day | High | Low | Chance of 0.01 in | Chance of 0.10 in | Daylight |
|---|---|---|---|---|---|
| September 1 | 76°F | 49°F | 22% | 12% | 13 h 20 min |
| September 2 | 76°F | 49°F | 22% | 12% | 13 h 20 min |
| September 3 | 76°F | 48°F | 22% | 12% | 13 h 20 min |
| September 4 | 75°F | 48°F | 23% | 13% | 13 h 10 min |
| September 5 | 75°F | 48°F | 23% | 13% | 13 h 10 min |
| September 6 | 75°F | 48°F | 24% | 13% | 13 h 10 min |
| September 7 | 75°F | 48°F | 24% | 13% | 13 h |
| September 8 | 75°F | 48°F | 24% | 14% | 13 h |
| September 9 | 74°F | 47°F | 25% | 14% | 13 h |
| September 10 | 74°F | 47°F | 25% | 14% | 13 h |
| September 11 | 74°F | 47°F | 26% | 15% | 12 h 50 min |
| September 12 | 74°F | 47°F | 26% | 15% | 12 h 50 min |
| September 13 | 73°F | 47°F | 27% | 15% | 12 h 50 min |
| September 14 | 73°F | 47°F | 27% | 16% | 12 h 40 min |
| September 15 | 73°F | 46°F | 28% | 16% | 12 h 40 min |
| September 16 | 72°F | 46°F | 28% | 16% | 12 h 40 min |
| September 17 | 72°F | 46°F | 29% | 17% | 12 h 30 min |
| September 18 | 72°F | 46°F | 29% | 17% | 12 h 30 min |
| September 19 | 71°F | 46°F | 30% | 17% | 12 h 30 min |
| September 20 | 71°F | 46°F | 30% | 18% | 12 h 20 min |
| September 21 | 71°F | 45°F | 31% | 18% | 12 h 20 min |
| September 22 | 70°F | 45°F | 31% | 19% | 12 h 20 min |
| September 23 | 70°F | 45°F | 32% | 19% | 12 h 10 min |
| September 24 | 70°F | 45°F | 33% | 19% | 12 h 10 min |
| September 25 | 69°F | 45°F | 33% | 20% | 12 h 10 min |
| September 26 | 69°F | 44°F | 34% | 20% | 12 h |
| September 27 | 68°F | 44°F | 34% | 21% | 12 h |
| September 28 | 68°F | 44°F | 35% | 21% | 12 h |
| September 29 | 67°F | 44°F | 36% | 22% | 11 h 50 min |
| September 30 | 67°F | 44°F | 36% | 22% | 11 h 50 min |
- Normal high
- 72°FSeptember average
- Normal low
- 46°FSeptember average
- Precipitation
- 2.04 inmonth total
- Days with precipitation
- 80.01 inch or more
- Daylight
- 13 h 20 min to 11 h 50 minSeptember 1 to September 30
- Days at 70°F or more
- 18
- Days at 80°F or more
- 5
- Sunshine
- 75%of clear-sky sunlight (NASA)
Source: NOAA NCEI 1991-2020 daily normals, station USW00024227; monthly normals. Daylight is computed from the place's latitude with NOAA's solar equations.
Does it rain in Olympia in September?
On a given September day the chance of 0.01 inch or more is 28% on average, highest around September 30 (36%). In all, 2.04 in falls on 8 days of a normal September.
Source: NOAA NCEI 1991-2020 daily and monthly normals, station USW00024227.
How humid and windy is Olympia in September?
At 3 p.m. the normal temperature is 66°F with 54% relative humidity and a dew point of 49°F; at 6 a.m. it is 47°F with 94% humidity. The wind averages 4.5 mph, most often from the west-northwest in the afternoon. A dew point under 50°F feels dry.
| Time | Temperature | Dew point | Humidity | Wind | Clear or few clouds |
|---|---|---|---|---|---|
| 6 a.m. | 47°F | 45°F | 94% | 2.7 mph | – |
| 9 a.m. | 55°F | 50°F | 84% | 5.3 mph | – |
| noon | 63°F | 50°F | 63% | 7.4 mph | 48% |
| 3 p.m. | 66°F | 49°F | 54% | 7.4 mph | 56% |
| 6 p.m. | 60°F | 49°F | 67% | 4.8 mph | 61% |
| 9 p.m. | 53°F | 49°F | 86% | 3.2 mph | 69% |
Source: NOAA NCEI 1991-2020 hourly normals, station USW00024227. Hourly normals exist only for NOAA's first-order stations; a dash where NOAA publishes no value for that hour (the sky at some hours).
What are the records for September in Olympia?
The warmest September temperature on Olympia's official record (since 1948) is 98°F, on September 2, 1988; the coldest is 25°F, on September 27, 1972. The wettest September brought 9.36 in (2013).
The September mean against the 1991-2020 normal of 59.1°F: 2021 59.7°F (+0.6), 2022 62.1°F (+3.0), 2023 59.6°F (+0.5), 2024 61.2°F (+2.1), 2025 61.7°F (+2.6), 2026 57.6°F (−1.5). 5 of 6 ran warmer than normal.
| September | Mean | Against normal | Precip. |
|---|---|---|---|
| 2021 | 59.7°F | +0.6°F | 3.31 in |
| 2022 | 62.1°F | +3.0°F | 0.13 in |
| 2023 | 59.6°F | +0.5°F | 2.30 in |
| 2024 | 61.2°F | +2.1°F | 1.91 in |
| 2025 | 61.7°F | +2.6°F | 1.28 in |
| 2026 | 57.6°F | −1.5°F | 1.91 in |
Source: records: ACIS, NWS threaded record OLMthr; recent months: ACIS, station USW00024227. Records and recent months use complete months only.
How does September in Olympia compare across Washington?
Across the 96 places PlainClimate covers in Washington, September normal highs run from 66°F in Coupeville to 81°F in Pasco; Olympia's is 72°F.
Source: NOAA NCEI 1991-2020 monthly normals for every station in the state.