| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 21°F | 87°F | 52°F | 4.9" |
| February | 30°F | 86°F | 53°F | 2.8" |
| March | 34°F | 90°F | 54°F | 2.1" |
| April | 36°F | 99°F | 55°F | 1.7" |
| May | 41°F | 96°F | 59°F | 0.7" |
| June | 41°F | 113°F | 62°F | 0.1" |
| July | 48°F | 93°F | 64°F | n/a |
| August | 48°F | 109°F | 64°F | 0.0" |
| September | 45°F | 101°F | 63°F | 0.0" |
| October | 41°F | 100°F | 61°F | 0.9" |
| November | 32°F | 93°F | 58°F | 0.6" |
| December | 28°F | 81°F | 51°F | 2.7" |
| Index | San Luis Obispo | California | National |
| Air quality index | 56 | 55 | 50 |
| Pollution index | 5,611,110 | 18,106,726 | 5,066,862 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 129 |
| Days with moderate air quality | 227 |
| Days w/ poor A.Q. for sensitive groups | 8 |
| Days with unhealthy air quality |
| Pollutant | Total |
| Arsenic | 0.020% |
| Benzene | 0.060% |
| Carbon Tetrachloride | 0.000% |
| Lead | 0.060% |
| Mercury | 0.010% |
| City, State | Population | Air Quality Index | National Avg. |
| Blacklake, CA | 895 | 56 | 12% |
| Garden Farms, CA | 312 | 56 | 12% |
| Los Ranchos, CA | 1,630 | 56 | 12% |
| Santa Margarita, CA | 1,346 | 56 | 12% |
| Callender, CA | 1,814 | 56 | 12% |
| San Luis Obispo, CA | 46,716 | 56 | 12% |
| City, State | Population | Air Quality Index | National Avg. |
| Palm Springs, CA | 46,714 | 85 | 70% |
| Twin Falls, ID | 46,623 | 13 | 74% |
| Texas City, TX | 46,811 | 52 | 4% |
| North Highlands, CA | 46,841 | 55 | 10% |
| Hattiesburg, MS | 46,846 | 39 | 22% |
| San Luis Obispo, CA | 46,716 | 56 | 12% |