| 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 | Grand Mound | Washington | National |
| Air quality index | 20 | 36 | 42 |
| Pollution index | 6,915,950 | 4,541,850 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 343 |
| Days with moderate air quality | 22 |
| Days w/ poor A.Q. for sensitive groups | 0 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.000% |
| Benzene | 0.110% |
| Carbon Tetrachloride | 0.010% |
| Lead | 0.000% |
| Mercury | 0.001% |
| City | Population | Air Quality Index | National Avg. |
| Oakville, WA | 647 | 20 | 60.0% |
| Chehalis, WA | 7,607 | 20 | 60.0% |
| Fords Prairie, WA | 2,582 | 20 | 60.0% |
| Rochester, WA | 4,854 | 20 | 60.0% |
| Bucoda, WA | 608 | 20 | 60.0% |
| Grand Mound, WA | 3,957 | 20 | 60.0% |
| City | Population | Air Quality Index | National Avg. |
| Lake San Marcos, CA | 3,957 | 64 | 28.0% |
| Southgate, KY | 3,957 | 54 | 8.0% |
| Level Green, PA | 3,957 | 56 | 12.0% |
| Ashland, MO | 3,956 | 38 | 24.0% |
| Weaverville, NC | 3,956 | 44 | 12.0% |
| Grand Mound, WA | 3,957 | 20 | 60.0% |
Here are the best places to live in Washington
These are the 10 cheapest cities in Washington
See the best places to live in Grand Mound
Most Dangerous States In The US