| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 36°F | 49°F | 42°F | 5.1" |
| February | 37°F | 52°F | 44°F | 3.8" |
| March | 40°F | 55°F | 47°F | 4.9" |
| April | 43°F | 61°F | 51°F | 3.1" |
| May | 49°F | 68°F | 57°F | 2.2" |
| June | 54°F | 72°F | 62°F | 1.5" |
| July | 58°F | 79°F | 67°F | 0.4" |
| August | 58°F | 79°F | 68°F | 0.6" |
| September | 54°F | 73°F | 62°F | 1.6" |
| October | 47°F | 62°F | 54°F | 3.9" |
| November | 40°F | 53°F | 47°F | 6.6" |
| December | 36°F | 48°F | 41°F | 6.1" |
| Index | Somerset | Bellevue | Washington |
| Air quality index | 45 | 45 | 36 |
| Pollution index | 1,081,430 | 1,081,430 | 4,541,850 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 236 |
| Days with moderate air quality | 127 |
| Days w/ poor A.Q. for sensitive groups | 2 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.000% |
| Benzene | 0.010% |
| Carbon Tetrachloride | 0.000% |
| Lead | 0.000% |
| Mercury | 0.000% |
| City | Population | Air Quality Index | National Avg. |
| Yarrow Point, WA | 1,353 | 45 | 10.0% |
| Fairwood CDP (Spokane County), WA | 8,055 | 45 | 10.0% |
| Covington, WA | 21,131 | 45 | 10.0% |
| Issaquah, WA | 38,707 | 45 | 10.0% |
| Boulevard Park, WA | 4,197 | 45 | 10.0% |
| Bellevue, WA | 146,145 | 45 | 10.0% |
| City | Population | Air Quality Index | National Avg. |
| Kelowna, BC | 145,612 | n/a | |
| Savannah, GA | 145,492 | 39 | 22.0% |
| Paterson, NJ | 145,484 | 51 | 2.0% |
| Saguenay, QC | 145,134 | n/a | |
| Bridgeport, CT | 145,014 | 43 | 14.0% |
| Bellevue, WA | 146,145 | 45 | 10.0% |
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