Weather and climate in Rocky Hill, NJ
What the weather is like in Rocky Hill
The warmest month in Rocky Hill is July, with average highs of 85°F. The coolest is January, when nights average 23°F. About 48.2 in of rain and snow falls in a typical year, most in June and least in February.
Skies are clearest in September (51% average cloud cover) and cloudiest in December (63%). Combining cloud with the length of truly dark nights, November, October, January offer the most clear, dark hours for stargazing.
Clear, dark hours per night
Hours of full astronomical darkness in mid-month, multiplied by the average share of clear sky. A rough guide to how much good observing time a typical night offers.
Monthly averages
| Month | High | Low | Precipitation | Cloud cover | Humidity | Wind | Dark hours |
|---|---|---|---|---|---|---|---|
| January | 37°F | 23°F | 3.2 in | 62% | 85% | 4 mph | 11.2 h |
| February | 39°F | 24°F | 3.1 in | 60% | 84% | 4 mph | 10.2 h |
| March | 47°F | 30°F | 4.0 in | 60% | 81% | 4 mph | 9.0 h |
| April | 60°F | 40°F | 3.9 in | 61% | 79% | 3 mph | 7.4 h |
| May | 69°F | 51°F | 3.9 in | 63% | 79% | 3 mph | 5.8 h |
| June | 79°F | 61°F | 4.6 in | 59% | 78% | 2 mph | 4.8 h |
| July | 85°F | 67°F | 4.6 in | 54% | 73% | 2 mph | 5.3 h |
| August | 84°F | 66°F | 4.5 in | 53% | 73% | 2 mph | 6.8 h |
| September | 78°F | 59°F | 3.8 in | 51% | 74% | 3 mph | 8.5 h |
| October | 65°F | 47°F | 4.5 in | 55% | 78% | 3 mph | 9.8 h |
| November | 53°F | 37°F | 3.6 in | 57% | 81% | 3 mph | 10.9 h |
| December | 43°F | 29°F | 4.5 in | 63% | 85% | 4 mph | 11.4 h |
Climate averages: NASA POWER, 2001–2025, for the grid area around 40.50, -74.38 (about 50 km across). High and low temperatures are estimated from the monthly mean and the average daily range. Hills, coasts and cities can differ from the area average. Aurora outlook for Rocky Hill · Sources and methods.