| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 36°F | 59°F | 46°F | 7.3" |
| February | 40°F | 63°F | 50°F | 3.6" |
| March | 48°F | 71°F | 59°F | 3.7" |
| April | 55°F | 78°F | 66°F | 6.6" |
| May | 62°F | 84°F | 73°F | 6.5" |
| June | 71°F | 93°F | 82°F | 7.0" |
| July | 74°F | 96°F | 85°F | 4.2" |
| August | 74°F | 97°F | 85°F | 5.7" |
| September | 66°F | 90°F | 77°F | 5.4" |
| October | 55°F | 80°F | 67°F | 10.9" |
| November | 47°F | 69°F | 57°F | 3.2" |
| December | 38°F | 60°F | 48°F | 3.7" |
| Index | Forest Hill | Texas | National |
| Air quality index | 51 | 52 | 42 |
| Pollution index | 453,692 | 2,009,300 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 181 |
| Days with moderate air quality | 155 |
| Days w/ poor A.Q. for sensitive groups | 28 |
| Days with unhealthy air quality | 1 |
| Pollutant | Total |
| Arsenic | 0.000% |
| Benzene | 0.005% |
| Carbon Tetrachloride | 0.000% |
| Lead | 0.003% |
| Mercury | 0.000% |
| City | Population | Air Quality Index | National Avg. |
| Lakeside, TX | 1,671 | 33 | 34.0% |
| River Oaks, TX | 7,830 | 33 | 34.0% |
| Cross Timber, TX | 298 | 33 | 34.0% |
| White Settlement, TX | 18,316 | 33 | 34.0% |
| Lake Worth, TX | 5,060 | 33 | 34.0% |
| Forest Hill, TX | 13,444 | 51 | 2.0% |
| City | Population | Air Quality Index | National Avg. |
| Perth East, ON | 13,452 | n/a | |
| Rocky Point, NY | 13,458 | 43 | 14.0% |
| Moody, AL | 13,428 | 53 | 6.0% |
| Red Oak, TX | 13,428 | 51 | 2.0% |
| Jupiter Farms, FL | 13,461 | 36 | 28.0% |
| Forest Hill, TX | 13,444 | 51 | 2.0% |