| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 12°F | 29°F | 20°F | 2.3" |
| February | 10°F | 30°F | 20°F | 1.4" |
| March | 19°F | 42°F | 30°F | 2.1" |
| April | 30°F | 57°F | 43°F | 3.5" |
| May | 42°F | 70°F | 56°F | 3.2" |
| June | 51°F | 79°F | 65°F | 3.9" |
| July | 55°F | 82°F | 69°F | 2.9" |
| August | 53°F | 80°F | 67°F | 3.0" |
| September | 46°F | 73°F | 59°F | 2.8" |
| October | 37°F | 60°F | 48°F | 3.1" |
| November | 28°F | 46°F | 37°F | 2.2" |
| December | 18°F | 33°F | 26°F | 2.2" |
| Index | West Branch | Michigan | National |
| Air quality index | 26 | 69 | 42 |
| Pollution index | 2,149,790 | 4,161,606 | 2,726,193 |
| Measurement | Total |
| Days measured | 316 |
| Days with good air quality | 288 |
| Days with moderate air quality | 28 |
| Days w/ poor A.Q. for sensitive groups | 0 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.001% |
| Benzene | 0.020% |
| Carbon Tetrachloride | 0.002% |
| Lead | 0.003% |
| Mercury | 0.000% |
| City | Population | Air Quality Index | National Avg. |
| Skidway Lake, MI | 3,388 | 26 | 48.0% |
| Lupton, MI | 311 | 26 | 48.0% |
| Rose City, MI | 692 | 26 | 48.0% |
| St. Helen, MI | 2,960 | 36 | 28.0% |
| West Branch, MI | 2,099 | 26 | 48.0% |
| City | Population | Air Quality Index | National Avg. |
| Somonauk, IL | 2,099 | 0 | 100.0% |
| Groton, NY | 2,099 | 34 | 32.0% |
| Marbury, AL | 2,100 | 52 | 4.0% |
| Kountze, TX | 2,098 | 45 | 10.0% |
| Wolf Creek, UT | 2,098 | 45 | 10.0% |
| West Branch, MI | 2,099 | 26 | 48.0% |