| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 39°F | 63°F | 50°F | 6.6" |
| February | 41°F | 67°F | 53°F | 7.7" |
| March | 48°F | 73°F | 60°F | 7.4" |
| April | 54°F | 80°F | 67°F | 9.5" |
| May | 62°F | 86°F | 73°F | 7.6" |
| June | 70°F | 91°F | 80°F | 10.6" |
| July | 72°F | 93°F | 81°F | 9.7" |
| August | 73°F | 92°F | 81°F | 9.9" |
| September | 68°F | 87°F | 76°F | 8.3" |
| October | 57°F | 80°F | 67°F | 7.5" |
| November | 46°F | 72°F | 57°F | 5.5" |
| December | 44°F | 67°F | 54°F | 6.6" |
| Index | Portal | Georgia | National |
| Air quality index | 42 | 41 | 50 |
| Pollution index | 1,428,370 | 3,237,553 | 5,066,862 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 251 |
| Days with moderate air quality | 112 |
| Days w/ poor A.Q. for sensitive groups | 2 |
| Days with unhealthy air quality |
| Pollutant | Total |
| Arsenic | 0.020% |
| Benzene | 0.020% |
| Carbon Tetrachloride | 0.002% |
| Lead | 0.040% |
| Mercury | 0.000% |
| City, State | Population | Air Quality Index | National Avg. |
| Metter, GA | 4,099 | 40 | 20% |
| Statesboro, GA | 30,597 | 40 | 20% |
| Pulaski, GA | 284 | 40 | 20% |
| Register, GA | 144 | 40 | 20% |
| Garfield, GA | 139 | 42 | 16% |
| Portal, GA | 641 | 42 | 16% |
| City, State | Population | Air Quality Index | National Avg. |
| East Nassau, NY | 641 | 44 | 12% |
| Woonsocket, SD | 641 | 35 | 30% |
| Eldred, PA | 641 | 33 | 34% |
| Thornton, AR | 641 | 4 | 92% |
| Flintville, TN | 641 | 37 | 26% |
| Portal, GA | 641 | 42 | 16% |