| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 18°F | 34°F | 25°F | 3.2" |
| February | 19°F | 36°F | 27°F | 2.6" |
| March | 32°F | 51°F | 40°F | 3.2" |
| April | 41°F | 64°F | 51°F | 5.2" |
| May | 51°F | 74°F | 62°F | 5.3" |
| June | 61°F | 83°F | 71°F | 9.7" |
| July | 64°F | 86°F | 74°F | 5.3" |
| August | 62°F | 84°F | 73°F | 9.8" |
| September | 55°F | 79°F | 66°F | 6.1" |
| October | 44°F | 65°F | 54°F | 7.0" |
| November | 34°F | 52°F | 42°F | 3.8" |
| December | 24°F | 38°F | 31°F | 3.7" |
| Index | Brook | Indiana | National |
| Air quality index | 42 | 56 | 42 |
| Pollution index | 2,020,430 | 2,719,453 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 276 |
| Days with moderate air quality | 89 |
| Days w/ poor A.Q. for sensitive groups | 0 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.002% |
| Benzene | 0.090% |
| Carbon Tetrachloride | 0.000% |
| Lead | 0.000% |
| Mercury | 0.001% |
| City | Population | Air Quality Index | National Avg. |
| Sheldon, IL | 1,222 | 42 | 16.0% |
| Mount Ayr, IN | 102 | 42 | 16.0% |
| Donovan, IL | 278 | 42 | 16.0% |
| Goodland, IN | 1,058 | 42 | 16.0% |
| Remington, IN | 1,432 | 42 | 16.0% |
| Brook, IN | 1,023 | 42 | 16.0% |
| City | Population | Air Quality Index | National Avg. |
| Cresson, TX | 1,023 | 33 | 34.0% |
| Improvement District No. 9 Banff, AB | 1,023 | n/a | |
| Geraldine, AL | 1,024 | 39 | 22.0% |
| Hayneville, AL | 1,022 | 52 | 4.0% |
| Green Valley CDP (Los Angeles County), CA | 1,024 | 35 | 30.0% |
| Brook, IN | 1,023 | 42 | 16.0% |