| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 12°F | 31°F | 21°F | 4.7" |
| February | 13°F | 33°F | 22°F | 2.9" |
| March | 21°F | 42°F | 31°F | 4.2" |
| April | 33°F | 57°F | 44°F | 4.6" |
| May | 43°F | 70°F | 56°F | 6.0" |
| June | 52°F | 76°F | 63°F | 6.8" |
| July | 57°F | 81°F | 68°F | 6.9" |
| August | 55°F | 79°F | 66°F | 8.1" |
| September | 48°F | 73°F | 59°F | 6.6" |
| October | 39°F | 60°F | 48°F | 8.7" |
| November | 28°F | 47°F | 37°F | 4.1" |
| December | 20°F | 36°F | 27°F | 5.0" |
| Index | Plymouth | New Hampshire | National |
| Air quality index | 31 | 34 | 42 |
| Pollution index | 5,847,470 | 3,959,618 | 2,726,193 |
| Measurement | Total |
| Days measured | 316 |
| Days with good air quality | 308 |
| Days with moderate air quality | 8 |
| Days w/ poor A.Q. for sensitive groups | 0 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.010% |
| Benzene | 0.050% |
| Carbon Tetrachloride | 0.010% |
| Lead | 0.180% |
| Mercury | 0.010% |
| City | Population | Air Quality Index | National Avg. |
| Ashland, NH | 1,630 | 31 | 38.0% |
| New Hampton, NH | 326 | 31 | 38.0% |
| Bristol, NH | 1,970 | 31 | 38.0% |
| Center Sandwich, NH | 98 | 31 | 38.0% |
| Laconia, NH | 16,584 | 31 | 38.0% |
| Plymouth, NH | 4,281 | 31 | 38.0% |
| City | Population | Air Quality Index | National Avg. |
| Ashville, OH | 4,281 | 46 | 8.0% |
| Waimanalo Beach, HI | 4,280 | 30 | 40.0% |
| Millinocket, ME | 4,280 | 31 | 38.0% |
| Magnolia, NJ | 4,280 | 51 | 2.0% |
| Alvarado, TX | 4,282 | 33 | 34.0% |
| Plymouth, NH | 4,281 | 31 | 38.0% |
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