Snohomish County Weather in September
Average highs run from 76°F on September 1 to 68°F on September 30, and lows from 50°F to 45°F. Normal precipitation for the month is 3.49 in over about 11 wet days.
September day by day
The normal high and low for each date, and the record, in °F.
- Normal low
- Normal high
- Record high
- Record low
September at a glance
- Average high
- 73°F
- Average low
- 47°F
- Precipitation
- 3.49 in
- Record high
- 92°FSep 3, 2017
- Record low
- 30°FSep 26, 2015
- Chance of a freeze
- 6%
- Days of 90°F or more
- 0.6
- Daylight
- 13 h 23 min to 11 h 43 min
- Cloud cover
- 52%
- Humidity
- 78%
- Dew point
- 44°F
- Wind
- 3.4 mph
Every day of the month
A wet day has at least 0.01 inch of precipitation; snow means at least 0.1 inch of snowfall.
| Date | Normal high | Normal low | Record high | Record low | Chance wet | Chance of snow |
|---|---|---|---|---|---|---|
| Sep 1 | 76°F | 50°F | 85°F 2013 | 42°F 2018 | 29% | 0% |
| Sep 2 | 76°F | 50°F | 89°F 2017 | 40°F 2018 | 30% | 0% |
| Sep 3 | 76°F | 49°F | 92°F 2017 | 39°F 2018 | 30% | 0% |
| Sep 4 | 76°F | 49°F | 88°F 2017 | 38°F 2018 | 31% | 0% |
| Sep 5 | 75°F | 49°F | 85°F 2017 | 40°F 2015 | 31% | 0% |
| Sep 6 | 75°F | 49°F | 89°F 2014 | 44°F 2018 | 32% | 0% |
| Sep 7 | 75°F | 49°F | 89°F 2012 | 44°F 2020 | 32% | 0% |
| Sep 8 | 75°F | 49°F | 85°F 2011 | 38°F 2016 | 33% | 0% |
| Sep 9 | 75°F | 49°F | 88°F 2020 | 38°F 2016 | 33% | 0% |
| Sep 10 | 74°F | 48°F | 89°F 2020 | 39°F 2014 | 34% | 0% |
| Sep 11 | 74°F | 48°F | 91°F 2013 | 35°F 2014 | 34% | 0% |
| Sep 12 | 74°F | 48°F | 82°F 2015 | 35°F 2014 | 35% | 0% |
| Sep 13 | 74°F | 48°F | 83°F 2014 | 37°F 2014 | 35% | 0% |
| Sep 14 | 73°F | 48°F | 88°F 2014 | 38°F 2017 | 36% | 0% |
| Sep 15 | 73°F | 48°F | 88°F 2014 | 37°F 2017 | 37% | 0% |
| Sep 16 | 73°F | 47°F | 80°F 2017 | 40°F 2015 | 37% | 0% |
| Sep 17 | 72°F | 47°F | 82°F 2012 | 36°F 2018 | 38% | 0% |
| Sep 18 | 72°F | 47°F | 85°F 2012 | 36°F 2018 | 39% | 0% |
| Sep 19 | 72°F | 47°F | 83°F 2013 | 38°F 2018 | 39% | 0% |
| Sep 20 | 71°F | 47°F | 80°F 2011 | 35°F 2016 | 40% | 0% |
| Sep 21 | 71°F | 46°F | 87°F 2014 | 35°F 2015 | 40% | 0% |
| Sep 22 | 71°F | 46°F | 76°F 2011 | 34°F 2015 | 41% | 0% |
| Sep 23 | 70°F | 46°F | 86°F 2011 | 35°F 2015 | 41% | 0% |
| Sep 24 | 70°F | 46°F | 82°F 2011 | 36°F 2018 | 42% | 0% |
| Sep 25 | 70°F | 46°F | 77°F 2016 | 37°F 2018 | 42% | 0% |
| Sep 26 | 69°F | 46°F | 78°F 2016 | 30°F 2015 | 43% | 0% |
| Sep 27 | 69°F | 45°F | 82°F 2017 | 31°F 2015 | 43% | 0% |
| Sep 28 | 69°F | 45°F | 89°F 2017 | 32°F 2015 | 44% | 0% |
| Sep 29 | 68°F | 45°F | 83°F 2011 | 34°F 2016 | 44% | 0% |
| Sep 30 | 68°F | 45°F | 70°F 2012 | 34°F 2016 | 45% | 0% |
Chance of rain
- Chance of a wet day
- Chance of snowfall
Sunrise and sunset
Times for 2026, local time (PDT).
- September 1
- sunrise 6:25 AM, sunset 7:48 PM
- September 30
- sunrise 7:05 AM, sunset 6:48 PM
Other months
Sources
Normals: NOAA NCEI U.S. Climate Normals, 1991-2020, station USC00458034 (Startup 1 E), public domain. Records: NOAA GHCN-Daily, station USC00450257, every year on file, quality-flagged values removed. Cloud, humidity, wind and sunshine: NASA POWER (MERRA-2, CERES and GEWEX SRB), 1991-2020. The data was obtained from the National Aeronautics and Space Administration (NASA) Langley Research Center's Prediction Of Worldwide Energy Resources (POWER) project funded through the NASA Earth Science Division: POWER Daily API v2, accessed 2026-09-24. Sun and moon: computed with the NOAA solar equations and Meeus.