| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 21°F | 41°F | 31°F | 2.8" |
| February | 22°F | 43°F | 31°F | 2.3" |
| March | 30°F | 53°F | 41°F | 3.7" |
| April | 39°F | 66°F | 52°F | 4.0" |
| May | 49°F | 75°F | 62°F | 3.7" |
| June | 58°F | 83°F | 70°F | 5.3" |
| July | 63°F | 87°F | 75°F | 5.3" |
| August | 61°F | 85°F | 72°F | 5.5" |
| September | 55°F | 79°F | 66°F | 3.6" |
| October | 43°F | 68°F | 55°F | 4.5" |
| November | 33°F | 56°F | 44°F | 3.0" |
| December | 27°F | 46°F | 36°F | 4.6" |
| Index | Somerville | New Jersey | National |
| Air quality index | 41 | 45 | 42 |
| Pollution index | 5,618,710 | 7,246,891 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 280 |
| Days with moderate air quality | 83 |
| Days w/ poor A.Q. for sensitive groups | 2 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.004% |
| Benzene | 0.060% |
| Carbon Tetrachloride | 0.020% |
| Lead | 0.040% |
| Mercury | 0.003% |
| City | Population | Air Quality Index | National Avg. |
| Long Valley, NJ | 2,327 | 34 | 32.0% |
| Annandale, NJ | 1,794 | 34 | 32.0% |
| Califon, NJ | 1,184 | 34 | 32.0% |
| High Bridge, NJ | 3,460 | 34 | 32.0% |
| Mendham, NJ | 4,880 | 34 | 32.0% |
| Somerville, NJ | 12,139 | 41 | 18.0% |
| City | Population | Air Quality Index | National Avg. |
| Fortuna, CA | 12,135 | 27 | 46.0% |
| Baraboo, WI | 12,133 | 35 | 30.0% |
| Sylacauga, AL | 12,132 | 38 | 24.0% |
| Cascades, VA | 12,132 | 47 | 6.0% |
| Lake Tapps, WA | 12,129 | 45 | 10.0% |
| Somerville, NJ | 12,139 | 41 | 18.0% |
Here are the best places to live in New Jersey
These are the 10 cheapest cities in New Jersey
Check out the 10 most dangerous cities in New Jersey
These are the largest cities in New Jersey