| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 36°F | 51°F | 43°F | 10.5" |
| February | 37°F | 53°F | 44°F | 6.7" |
| March | 39°F | 55°F | 46°F | 9.5" |
| April | 40°F | 57°F | 49°F | 6.0" |
| May | 45°F | 63°F | 53°F | 4.1" |
| June | 50°F | 66°F | 57°F | 2.4" |
| July | 53°F | 69°F | 60°F | 1.0" |
| August | 53°F | 71°F | 61°F | 0.8" |
| September | 50°F | 70°F | 59°F | 3.3" |
| October | 45°F | 63°F | 53°F | 7.4" |
| November | 40°F | 55°F | 47°F | 12.7" |
| December | 36°F | 49°F | 42°F | 11.3" |
| Index | Ilwaco | Washington | National |
| Air quality index | 20 | 36 | 42 |
| Pollution index | 2,873,390 | 4,541,850 | 2,726,193 |
| Measurement | Total |
| Days measured | 352 |
| Days with good air quality | 348 |
| Days with moderate air quality | 4 |
| Days w/ poor A.Q. for sensitive groups | 0 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.010% |
| Benzene | 0.050% |
| Carbon Tetrachloride | 0.010% |
| Lead | 0.010% |
| Mercury | 0.010% |
| City | Population | Air Quality Index | National Avg. |
| Jeffers Gardens, OR | 312 | 18 | 64.0% |
| Warrenton, OR | 5,635 | 18 | 64.0% |
| Chinook, WA | 168 | 18 | 64.0% |
| Astoria, OR | 9,929 | 18 | 64.0% |
| Naselle, WA | 585 | 20 | 60.0% |
| Ilwaco, WA | 1,431 | 20 | 60.0% |
| City | Population | Air Quality Index | National Avg. |
| Malta, IL | 1,431 | 42 | 16.0% |
| Pine Knot, KY | 1,431 | 40 | 20.0% |
| Tryon, NC | 1,431 | 44 | 12.0% |
| Pemberville, OH | 1,431 | 40 | 20.0% |
| Schwenksville, PA | 1,431 | 42 | 16.0% |
| Ilwaco, WA | 1,431 | 20 | 60.0% |
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