| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 38°F | 60°F | 47°F | 6.0" |
| February | 44°F | 62°F | 52°F | 7.2" |
| March | 44°F | 65°F | 53°F | 5.4" |
| April | 43°F | 67°F | 54°F | 2.8" |
| May | 48°F | 69°F | 57°F | 1.3" |
| June | 50°F | 72°F | 59°F | 2.4" |
| July | 54°F | 73°F | 61°F | 0.1" |
| August | 53°F | 74°F | 61°F | 0.0" |
| September | 51°F | 74°F | 60°F | 1.9" |
| October | 47°F | 73°F | 58°F | 2.0" |
| November | 45°F | 69°F | 55°F | 2.7" |
| December | 41°F | 61°F | 50°F | 9.8" |
| Index | Gilroy | California | National |
| Air quality index | 37 | 55 | 42 |
| Pollution index | 5,429,550 | 10,473,190 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 330 |
| Days with moderate air quality | 34 |
| Days w/ poor A.Q. for sensitive groups | 1 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.020% |
| Benzene | 0.080% |
| Carbon Tetrachloride | 0.000% |
| Lead | 0.050% |
| Mercury | 0.150% |
| City | Population | Air Quality Index | National Avg. |
| Aptos Hills-Larkin Valley, CA | 1,397 | 35 | 30.0% |
| Day Valley, CA | 3,414 | 35 | 30.0% |
| Corralitos, CA | 2,260 | 35 | 30.0% |
| Freedom, CA | 3,959 | 35 | 30.0% |
| La Selva Beach, CA | 2,544 | 35 | 30.0% |
| Gilroy, CA | 55,227 | 37 | 26.0% |
| City | Population | Air Quality Index | National Avg. |
| Apex, NC | 55,220 | 46 | 8.0% |
| Carson City, NV | 55,244 | 41 | 18.0% |
| Chicopee, MA | 55,186 | 40 | 20.0% |
| Kettering, OH | 55,271 | 47 | 6.0% |
| Hempstead, NY | 55,153 | 51 | 2.0% |
| Gilroy, CA | 55,227 | 37 | 26.0% |
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