| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 36°F | 60°F | 48°F | 2.1" |
| February | 38°F | 66°F | 52°F | 2.9" |
| March | 42°F | 72°F | 56°F | 2.3" |
| April | 46°F | 77°F | 61°F | 3.2" |
| May | 52°F | 83°F | 67°F | 1.0" |
| June | 63°F | 96°F | 80°F | 4.8" |
| July | 66°F | 98°F | 83°F | 1.0" |
| August | 65°F | 98°F | 82°F | 0.9" |
| September | 59°F | 91°F | 75°F | 1.7" |
| October | 50°F | 80°F | 65°F | 3.5" |
| November | 41°F | 69°F | 54°F | 1.0" |
| December | 35°F | 59°F | 46°F | 4.3" |
| Index | Phelan | California | National |
| Air quality index | 89 | 55 | 42 |
| Pollution index | 31,575,300 | 10,473,190 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 42 |
| Days with moderate air quality | 178 |
| Days w/ poor A.Q. for sensitive groups | 79 |
| Days with unhealthy air quality | 58 |
| Pollutant | Total |
| Arsenic | 0.110% |
| Benzene | 0.260% |
| Carbon Tetrachloride | 0.020% |
| Lead | 0.350% |
| Mercury | 0.280% |
| City | Population | Air Quality Index | National Avg. |
| Lake Los Angeles, CA | 12,394 | 72 | 44.0% |
| Oak Hills, CA | 10,811 | 89 | 78.0% |
| Piñon Hills, CA | 7,136 | 89 | 78.0% |
| Wrightwood, CA | 4,488 | 89 | 78.0% |
| Adelanto, CA | 35,081 | 89 | 78.0% |
| Phelan, CA | 19,739 | 89 | 78.0% |
| City | Population | Air Quality Index | National Avg. |
| Mont-Saint-Hilaire, QC | 19,745 | n/a | |
| Mineola, NY | 19,748 | 51 | 2.0% |
| Hermosa Beach, CA | 19,749 | 72 | 44.0% |
| North Liberty, IA | 19,749 | 35 | 30.0% |
| Erlanger, KY | 19,751 | 54 | 8.0% |
| Phelan, CA | 19,739 | 89 | 78.0% |