| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 29°F | 44°F | 36°F | 4.8" |
| February | 29°F | 45°F | 36°F | 3.9" |
| March | 36°F | 54°F | 44°F | 5.5" |
| April | 47°F | 66°F | 55°F | 5.8" |
| May | 56°F | 73°F | 64°F | 6.3" |
| June | 67°F | 83°F | 74°F | 6.4" |
| July | 71°F | 86°F | 78°F | 6.7" |
| August | 70°F | 84°F | 77°F | 7.1" |
| September | 65°F | 80°F | 72°F | 5.9" |
| October | 53°F | 69°F | 61°F | 6.4" |
| November | 42°F | 58°F | 49°F | 5.2" |
| December | 33°F | 48°F | 40°F | 5.9" |
| Index | Riva | Maryland | National |
| Air quality index | 47 | 43 | 42 |
| Pollution index | 3,494,010 | 5,342,367 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 209 |
| Days with moderate air quality | 145 |
| Days w/ poor A.Q. for sensitive groups | 10 |
| Days with unhealthy air quality | 1 |
| Pollutant | Total |
| Arsenic | 0.010% |
| Benzene | 0.040% |
| Carbon Tetrachloride | 0.002% |
| Lead | 0.010% |
| Mercury | 0.001% |
| City | Population | Air Quality Index | National Avg. |
| Pasadena, MD | 29,432 | 46 | 8.0% |
| Severn, MD | 53,374 | 46 | 8.0% |
| Naval Academy, MD | 5,609 | 46 | 8.0% |
| Stevensville, MD | 8,145 | 46 | 8.0% |
| Cape St. Claire, MD | 8,405 | 46 | 8.0% |
| Riva, MD | 4,321 | 47 | 6.0% |
| City | Population | Air Quality Index | National Avg. |
| Grantley, PA | 4,320 | 41 | 18.0% |
| Pixley, CA | 4,322 | 66 | 32.0% |
| Chester, MD | 4,319 | 46 | 8.0% |
| Cornwall, PA | 4,319 | 42 | 16.0% |
| Buena, NJ | 4,323 | 40 | 20.0% |
| Riva, MD | 4,321 | 47 | 6.0% |
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