Weather and climate in Monticello, WI
What the weather is like in Monticello
The warmest month in Monticello is July, with average highs of 83°F. The coolest is January, when nights average 11°F. About 38.1 in of rain and snow falls in a typical year, most in June and least in January.
Skies are clearest in September (47% average cloud cover) and cloudiest in December (70%). Combining cloud with the length of truly dark nights, September, October, November 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 | 27°F | 11°F | 1.5 in | 67% | 88% | 9 mph | 11.3 h |
| February | 31°F | 13°F | 1.7 in | 64% | 85% | 9 mph | 10.2 h |
| March | 45°F | 25°F | 2.4 in | 63% | 80% | 8 mph | 8.9 h |
| April | 58°F | 36°F | 3.7 in | 62% | 76% | 8 mph | 7.2 h |
| May | 69°F | 48°F | 4.3 in | 63% | 77% | 7 mph | 5.3 h |
| June | 79°F | 59°F | 5.1 in | 56% | 77% | 6 mph | 4.1 h |
| July | 83°F | 63°F | 4.1 in | 48% | 76% | 5 mph | 4.7 h |
| August | 81°F | 61°F | 4.2 in | 49% | 75% | 5 mph | 6.5 h |
| September | 74°F | 53°F | 3.7 in | 47% | 76% | 6 mph | 8.3 h |
| October | 60°F | 40°F | 3.2 in | 59% | 77% | 7 mph | 9.8 h |
| November | 45°F | 29°F | 2.2 in | 64% | 81% | 7 mph | 11.0 h |
| December | 32°F | 18°F | 2.1 in | 70% | 88% | 8 mph | 11.5 h |
Climate averages: NASA POWER, 2001–2025, for the grid area around 42.50, -89.38 (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 Monticello · Sources and methods.