Washington · county records since 1895, through September 2026.
Weather › Washington › Lewis County
10 of the last 12 months ran warmer than usual in Lewis County. September 2026 averaged 55.2° there, 2.4° below the usual for September (86th warmest of 132).
That is the 1991 to 2020 average for these dates in Lewis County. The Weather Service forecast fills in below.
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Each bar is a month's average temperature against the usual for that month (1991 to 2020). Ranks compare the same month in every year since 1895.
Rain and melted snow against the usual for each month. The drought reading is NOAA's Palmer index for the county.
| Month | Usual high / low | Usual rain | Warmest | Coldest |
|---|---|---|---|---|
| January | 42° / 31° | 10.6 in | 40.8° 2015 | 21.8° 1950 |
| February | 45° / 31° | 7.6 in | 43.9° 2015 | 28.7° 1936 |
| March | 49° / 33° | 8.0 in | 46.1° 1992 | 34.0° 1955 |
| April | 55° / 36° | 5.9 in | 51.6° 1926 | 39.1° 1955 |
| May | 62° / 41° | 4.0 in | 56.4° 1958 | 45.6° 1933 |
| June | 67° / 45° | 2.9 in | 62.2° 2015 | 51.2° 1971 |
| July | 75° / 50° | 0.9 in | 66.1° 1958 | 56.8° 1955 |
| August | 75° / 50° | 1.3 in | 67.4° 2022 | 56.5° 1899 |
| September | 69° / 46° | 2.9 in | 61.5° 2025 | 50.7° 1895 |
| October | 57° / 39° | 7.0 in | 55.2° 2022 | 43.7° 2019 |
| November | 46° / 34° | 10.8 in | 45.6° 1949 | 31.0° 1985 |
| December | 41° / 30° | 11.1 in | 40.8° 1950 | 29.1° 1990 |
Warmest and coldest are the month's whole-month average temperature, with the year it happened.