| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 34°F | 54°F | 43°F | 5.3" |
| February | 40°F | 62°F | 50°F | 4.4" |
| March | 44°F | 71°F | 56°F | 3.7" |
| April | 44°F | 74°F | 59°F | 3.5" |
| May | 52°F | 84°F | 67°F | 2.7" |
| June | 55°F | 89°F | 72°F | 0.3" |
| July | 63°F | 97°F | 80°F | 0.1" |
| August | 61°F | 97°F | 79°F | 0.0" |
| September | 54°F | 87°F | 69°F | 3.9" |
| October | 48°F | 79°F | 62°F | 2.1" |
| November | 41°F | 69°F | 54°F | 1.2" |
| December | 38°F | 56°F | 46°F | 2.5" |
| Index | McSwain | California | National |
| Air quality index | 48 | 55 | 42 |
| Pollution index | 5,213,360 | 10,473,190 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 213 |
| Days with moderate air quality | 145 |
| Days w/ poor A.Q. for sensitive groups | 7 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.030% |
| Benzene | 0.090% |
| Carbon Tetrachloride | 0.000% |
| Lead | 0.040% |
| Mercury | 0.060% |
| City | Population | Air Quality Index | National Avg. |
| Cressey, CA | 243 | 48 | 4.0% |
| Stevinson, CA | 196 | 48 | 4.0% |
| Bear Creek, CA | 95 | 48 | 4.0% |
| Merced, CA | 84,081 | 48 | 4.0% |
| Delhi, CA | 11,837 | 48 | 4.0% |
| McSwain, CA | 4,429 | 48 | 4.0% |
| City | Population | Air Quality Index | National Avg. |
| Pendleton, IN | 4,429 | 42 | 16.0% |
| Church Point, LA | 4,429 | 41 | 18.0% |
| North Okanagan C, BC | 4,428 | n/a | |
| Springville, AL | 4,430 | 53 | 6.0% |
| Dilworth, MN | 4,430 | 33 | 34.0% |
| McSwain, CA | 4,429 | 48 | 4.0% |
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