| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 34°F | 65°F | 49°F | 10.5" |
| February | 39°F | 65°F | 51°F | 8.0" |
| March | 41°F | 70°F | 54°F | 3.0" |
| April | 41°F | 72°F | 55°F | 2.9" |
| May | 48°F | 77°F | 61°F | 0.9" |
| June | 49°F | 83°F | 65°F | 0.2" |
| July | 56°F | 91°F | 72°F | 1.5" |
| August | 58°F | 92°F | 73°F | 0.5" |
| September | 50°F | 86°F | 67°F | 0.4" |
| October | 47°F | 79°F | 62°F | 2.1" |
| November | 42°F | 75°F | 57°F | 3.5" |
| December | 34°F | 67°F | 50°F | 2.5" |
| Index | Julian | California | National |
| Air quality index | 64 | 55 | 42 |
| Pollution index | 162,740 | 10,473,190 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 87 |
| Days with moderate air quality | 253 |
| Days w/ poor A.Q. for sensitive groups | 23 |
| Days with unhealthy air quality | 2 |
| Pollutant | Total |
| Arsenic | 0.000% |
| Benzene | 0.003% |
| Carbon Tetrachloride | 0.000% |
| Lead | 0.000% |
| Mercury | 0.000% |
| City | Population | Air Quality Index | National Avg. |
| Descanso, CA | 1,398 | 64 | 28.0% |
| Mount Laguna, CA | 102 | 64 | 28.0% |
| San Diego Country Estates, CA | 9,752 | 64 | 28.0% |
| Borrego Springs, CA | 1,864 | 64 | 28.0% |
| Julian, CA | 1,318 | 64 | 28.0% |
| City | Population | Air Quality Index | National Avg. |
| La Harpe, IL | 1,318 | 29 | 42.0% |
| Mulberry, IN | 1,319 | 42 | 16.0% |
| Coal Run Village, KY | 1,319 | 42 | 16.0% |
| Red Lake Falls, MN | 1,319 | 33 | 34.0% |
| Winthrop, MN | 1,317 | 46 | 8.0% |
| Julian, CA | 1,318 | 64 | 28.0% |
Here are the best places to live in California
Check out the 10 safest cities in California
Most Dangerous States In The US
Check out the 10 most dangerous cities in California