| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 38°F | 59°F | 47°F | 4.3" |
| February | 41°F | 62°F | 51°F | 3.4" |
| March | 49°F | 70°F | 59°F | 4.7" |
| April | 56°F | 78°F | 66°F | 4.5" |
| May | 64°F | 84°F | 73°F | 3.6" |
| June | 72°F | 92°F | 81°F | 3.4" |
| July | 75°F | 94°F | 83°F | 4.0" |
| August | 75°F | 95°F | 84°F | 2.7" |
| September | 68°F | 90°F | 78°F | 3.0" |
| October | 56°F | 80°F | 67°F | 4.1" |
| November | 47°F | 69°F | 57°F | 4.1" |
| December | 40°F | 60°F | 49°F | 4.3" |
| Index | Gilliam | Louisiana | National |
| Air quality index | 39 | 106 | 42 |
| Pollution index | 5,952,760 | 2,526,475 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 291 |
| Days with moderate air quality | 74 |
| Days w/ poor A.Q. for sensitive groups | 0 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.004% |
| Benzene | 0.070% |
| Carbon Tetrachloride | 0.020% |
| Lead | 0.080% |
| Mercury | 0.002% |
| City | Population | Air Quality Index | National Avg. |
| Hosston, LA | 292 | 39 | 22.0% |
| Rodessa, LA | 168 | 39 | 22.0% |
| Plain Dealing, LA | 1,003 | 39 | 22.0% |
| Ida, LA | 279 | 39 | 22.0% |
| Vivian, LA | 3,531 | 39 | 22.0% |
| Gilliam, LA | 109 | 39 | 22.0% |
| City | Population | Air Quality Index | National Avg. |
| Eagle, AK | 109 | 38 | 24.0% |
| Mud Bay, AK | 109 | 20 | 60.0% |
| Standing Rock, AL | 109 | 42 | 16.0% |
| Kohls Ranch, AZ | 109 | 60 | 20.0% |
| Vilas, CO | 109 | 20 | 60.0% |
| Gilliam, LA | 109 | 39 | 22.0% |
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