| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 44°F | 65°F | 53°F | 5.2" |
| February | 45°F | 66°F | 54°F | 5.0" |
| March | 51°F | 74°F | 62°F | 3.1" |
| April | 58°F | 80°F | 68°F | 3.2" |
| May | 66°F | 86°F | 75°F | 5.7" |
| June | 72°F | 92°F | 81°F | 3.0" |
| July | 74°F | 92°F | 82°F | 5.2" |
| August | 74°F | 93°F | 82°F | 7.9" |
| September | 70°F | 89°F | 78°F | 6.9" |
| October | 58°F | 81°F | 69°F | 5.6" |
| November | 49°F | 73°F | 59°F | 2.7" |
| December | 45°F | 66°F | 54°F | 9.3" |
| Index | Monticello | Louisiana | National |
| Air quality index | 45 | 106 | 42 |
| Pollution index | 1,932,420 | 2,526,475 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 224 |
| Days with moderate air quality | 132 |
| Days w/ poor A.Q. for sensitive groups | 9 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.000% |
| Benzene | 0.030% |
| Carbon Tetrachloride | 0.060% |
| Lead | 0.000% |
| Mercury | 0.000% |
| City | Population | Air Quality Index | National Avg. |
| French Settlement, LA | 960 | 45 | 10.0% |
| Denham Springs, LA | 9,908 | 45 | 10.0% |
| Shenandoah, LA | 21,045 | 45 | 10.0% |
| Baker, LA | 13,233 | 45 | 10.0% |
| Merrydale, LA | 9,523 | 45 | 10.0% |
| Monticello, LA | 4,926 | 45 | 10.0% |
| City | Population | Air Quality Index | National Avg. |
| Adairsville, GA | 4,926 | 44 | 12.0% |
| Duryea, PA | 4,926 | 38 | 24.0% |
| Ironwood, MI | 4,925 | 8 | 84.0% |
| Adel, IA | 4,924 | 39 | 22.0% |
| Osage Beach, MO | 4,923 | 39 | 22.0% |
| Monticello, LA | 4,926 | 45 | 10.0% |
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