| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 32°F | 47°F | 39°F | 7.3" |
| February | 32°F | 51°F | 41°F | 4.8" |
| March | 35°F | 55°F | 44°F | 7.0" |
| April | 36°F | 61°F | 48°F | 3.5" |
| May | 42°F | 68°F | 55°F | 2.7" |
| June | 47°F | 73°F | 59°F | 1.5" |
| July | 50°F | 80°F | 64°F | 0.6" |
| August | 50°F | 81°F | 64°F | 1.0" |
| September | 46°F | 74°F | 59°F | 2.5" |
| October | 41°F | 62°F | 51°F | 5.5" |
| November | 35°F | 52°F | 44°F | 9.7" |
| December | 31°F | 46°F | 38°F | 8.0" |
| Index | Tumwater | Washington | National |
| Air quality index | 30 | 36 | 42 |
| Pollution index | 6,704,330 | 4,541,850 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 323 |
| Days with moderate air quality | 42 |
| Days w/ poor A.Q. for sensitive groups | 0 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.003% |
| Benzene | 0.100% |
| Carbon Tetrachloride | 0.004% |
| Lead | 0.030% |
| Mercury | 0.003% |
| City | Population | Air Quality Index | National Avg. |
| Grand Mound, WA | 3,957 | 20 | 60.0% |
| Rochester, WA | 4,854 | 20 | 60.0% |
| Oakville, WA | 647 | 20 | 60.0% |
| Bucoda, WA | 608 | 20 | 60.0% |
| Tenino, WA | 1,744 | 20 | 60.0% |
| Tumwater, WA | 23,390 | 30 | 40.0% |
| City | Population | Air Quality Index | National Avg. |
| Wilmington, MA | 23,390 | 43 | 14.0% |
| North Augusta, SC | 23,370 | 47 | 6.0% |
| Lisle, IL | 23,363 | 55 | 10.0% |
| Oak Harbor, WA | 23,358 | 24 | 52.0% |
| Maywood, IL | 23,351 | 55 | 10.0% |
| Tumwater, WA | 23,390 | 30 | 40.0% |
Here are the best places to live in Washington
Check out the 10 most dangerous cities in Washington
These are the 10 cheapest cities in Washington
Safest Cities In The US