| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 42°F | 64°F | 52°F | 10.7" |
| February | 46°F | 69°F | 56°F | 9.6" |
| March | 52°F | 74°F | 62°F | 9.5" |
| April | 59°F | 80°F | 69°F | 12.2" |
| May | 63°F | 84°F | 73°F | 18.2" |
| June | 72°F | 89°F | 80°F | 8.0" |
| July | 73°F | 91°F | 81°F | 7.0" |
| August | 73°F | 91°F | 80°F | 13.6" |
| September | 70°F | 89°F | 78°F | 8.0" |
| October | 59°F | 82°F | 69°F | 9.8" |
| November | 49°F | 73°F | 60°F | 6.0" |
| December | 47°F | 68°F | 56°F | 6.6" |
| Index | Romeville | Louisiana | National |
| Air quality index | 45 | 106 | 42 |
| Pollution index | 2,337,990 | 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 | 0.010% |
| Benzene | 0.030% |
| Carbon Tetrachloride | 0.004% |
| Lead | 0.002% |
| Mercury | 0.000% |
| City | Population | Air Quality Index | National Avg. |
| Garyville, LA | 1,966 | 30 | 40.0% |
| Supreme, LA | 494 | 41 | 18.0% |
| Grand Point, LA | 2,798 | 41 | 18.0% |
| Paulina, LA | 1,761 | 41 | 18.0% |
| St. James, LA | 596 | 41 | 18.0% |
| Romeville, LA | 107 | 45 | 10.0% |
| City | Population | Air Quality Index | National Avg. |
| Newhalen, AK | 107 | 31 | 38.0% |
| Casa, AR | 107 | 38 | 24.0% |
| Fifty-Six, AR | 107 | 36 | 28.0% |
| Timber Cove, CA | 107 | 34 | 32.0% |
| Bark Ranch, CO | 107 | 47 | 6.0% |
| Romeville, LA | 107 | 45 | 10.0% |
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