Seattle in September
Find out everything about the water temperature in Seattle in September. Average, minimum and maximum recorded temperatures as well as daily temperature in September for the last two years. Compare the current month's sea temperature data with other months of the year.
Water temperature in September
Minimum:
54.6 °F
Average:
56.8 °F
Maximum:
59.5 °F
Sea water temperature in Seattle in September
In the city of Seattle, the month of September is too cold for swimming. The minimum recorded temperature during this month was 54.6°F on September 27, 2024, with an average temperature being 56.8°F and a maximum temperature reaching 59.5°F on September 4, 2017.
| Date | 10 years average | 2024 | 2023 |
|---|---|---|---|
| Sep 1 | 57.6°F | 58.1°F | 57.1°F |
| Sep 2 | 57.7°F | 58.8°F | 56.8°F |
| Sep 3 | 57.7°F | 58.6°F | 57.2°F |
| Sep 4 | 57.8°F | 58.6°F | 57.2°F |
| Sep 5 | 57.3°F | 58.2°F | 55.5°F |
| Sep 6 | 57.0°F | 56.8°F | 56.2°F |
| Sep 7 | 57.2°F | 57.6°F | 56.5°F |
| Sep 8 | 57.2°F | 57.7°F | 57.2°F |
| Sep 9 | 57.3°F | 59.2°F | 57.4°F |
| Sep 10 | 57.1°F | 58.6°F | 57.9°F |
| Sep 11 | 57.2°F | 58.0°F | 58.0°F |
| Sep 12 | 56.9°F | 56.9°F | 58.7°F |
| Sep 13 | 57.0°F | 57.5°F | 58.3°F |
| Sep 14 | 56.8°F | 57.3°F | 57.8°F |
| Sep 15 | 56.8°F | 57.0°F | 57.7°F |
| Sep 16 | 56.6°F | 56.0°F | 57.7°F |
| Sep 17 | 56.5°F | 56.7°F | 57.6°F |
| Sep 18 | 56.2°F | 56.3°F | 56.5°F |
| Sep 19 | 56.2°F | 56.7°F | 56.2°F |
| Sep 20 | 55.9°F | 56.1°F | 56.0°F |
| Sep 21 | 56.0°F | 55.7°F | 55.5°F |
| Sep 22 | 56.2°F | 56.1°F | 56.2°F |
| Sep 23 | 56.1°F | 56.1°F | 56.2°F |
| Sep 24 | 56.2°F | 56.8°F | 57.7°F |
| Sep 25 | 56.3°F | 56.5°F | 57.2°F |
| Sep 26 | 56.4°F | 56.5°F | 56.8°F |
| Sep 27 | 56.1°F | 54.6°F | 56.2°F |
| Sep 28 | 56.3°F | 55.3°F | 55.9°F |
| Sep 29 | 56.6°F | 56.1°F | 56.4°F |
| Sep 30 | 56.3°F | 55.3°F | 55.9°F |
In an average year, Seattle offers no days when the water temperature is warm enough to swim comfortably.
The warmest water in Seattle was recorded on July 6, 2021, reaching a 63.4°F. While the coldest temperature occurred on February 5, 2014, dipping to 44.4°F. The average readings by season are 47.6°F in Winter, 49.6°F in Spring, 57.1°F in Summer, and 54.3°F in Autumn.
September's average temperature is a slight drop from August's average of 58.2°F. In October, the temperature is expected to decrease further, potentially averaging around 54.5°F.