| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 41°F | 66°F | 52°F | 10.0" |
| February | 44°F | 68°F | 54°F | 5.7" |
| March | 46°F | 75°F | 58°F | 2.7" |
| April | 47°F | 78°F | 60°F | 1.7" |
| May | 53°F | 83°F | 66°F | 2.2" |
| June | 55°F | 88°F | 70°F | 1.2" |
| July | 63°F | 96°F | 78°F | 0.0" |
| August | 63°F | 96°F | 78°F | 0.1" |
| September | 56°F | 88°F | 70°F | 1.0" |
| October | 51°F | 83°F | 64°F | 3.9" |
| November | 46°F | 78°F | 59°F | 19.8" |
| December | 39°F | 66°F | 51°F | 4.9" |
| Index | Redlands | California | National |
| Air quality index | 85 | 55 | 50 |
| Pollution index | 31,575,300 | 18,106,726 | 5,066,862 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 24 |
| Days with moderate air quality | 211 |
| Days w/ poor A.Q. for sensitive groups | 102 |
| Days with unhealthy air quality | 25 |
| Pollutant | Total |
| Arsenic | 0.110% |
| Benzene | 0.260% |
| Carbon Tetrachloride | 0.020% |
| Lead | 0.350% |
| Mercury | 0.280% |
| City, State | Population | Air Quality Index | National Avg. |
| Beaumont, CA | 42,191 | 85 | 70% |
| Colton, CA | 53,856 | 85 | 70% |
| Highland, CA | 54,490 | 85 | 70% |
| Mentone, CA | 9,901 | 85 | 70% |
| Rialto, CA | 102,418 | 85 | 70% |
| Redlands, CA | 70,442 | 85 | 70% |
| City, State | Population | Air Quality Index | National Avg. |
| Lauderhill, FL | 70,452 | 41 | 18% |
| Passaic, NJ | 70,536 | 53 | 6% |
| Franklin, TN | 70,625 | 45 | 10% |
| Rock Hill, SC | 70,251 | 42 | 16% |
| Framingham, MA | 70,743 | 38 | 24% |
| Redlands, CA | 70,442 | 85 | 70% |