| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 45°F | 69°F | 56°F | 1.9" |
| February | 47°F | 69°F | 57°F | 2.2" |
| March | 50°F | 70°F | 59°F | 1.0" |
| April | 53°F | 72°F | 61°F | 0.7" |
| May | 57°F | 72°F | 63°F | 0.4" |
| June | 61°F | 76°F | 66°F | 0.0" |
| July | 65°F | 80°F | 71°F | 0.2" |
| August | 66°F | 82°F | 72°F | 0.0" |
| September | 64°F | 83°F | 72°F | 0.2" |
| October | 58°F | 80°F | 68°F | 0.5" |
| November | 51°F | 74°F | 62°F | 0.9" |
| December | 46°F | 68°F | 56°F | 2.5" |
| Index | La Mesa | California | National |
| Air quality index | 64 | 55 | 42 |
| Pollution index | 45,820,500 | 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 | 1.130% |
| Benzene | 0.410% |
| Carbon Tetrachloride | 0.030% |
| Lead | 0.600% |
| Mercury | 0.080% |
| City | Population | Air Quality Index | National Avg. |
| Imperial Beach, CA | 27,334 | 64 | 28.0% |
| National City, CA | 61,342 | 64 | 28.0% |
| Bostonia, CA | 17,532 | 64 | 28.0% |
| Eucalyptus Hills, CA | 6,448 | 64 | 28.0% |
| Rancho San Diego, CA | 21,476 | 64 | 28.0% |
| La Mesa, CA | 60,208 | 64 | 28.0% |
| City | Population | Air Quality Index | National Avg. |
| Mirabel, QC | 60,296 | n/a | |
| Sanford, FL | 60,337 | 37 | 26.0% |
| Bristol, CT | 60,039 | 37 | 26.0% |
| Ocala, FL | 60,021 | 38 | 24.0% |
| Utica, NY | 59,984 | 27 | 46.0% |
| La Mesa, CA | 60,208 | 64 | 28.0% |
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