Photo: TheCatalyst31 · CC BY-SA 4.0January in Fontana-on-Geneva Lake bites harder than in 90% of U.S. towns
Peak summer warmth arrives in July, with afternoons near 83°. Winter and summer sit 70° apart. Summers stay cool: July afternoons here are cooler than in 74% of U.S. towns. Comfortable outdoor weather lasts from May to September, with highs of 69–83°.
A year in Fontana-on-Geneva Lake at a glance
Each month’s typical high and low, and what it brings.
What stands out about Fontana-on-Geneva Lake’s climate
Compared with towns across the U.S., with Fontana-on-Geneva Lake’s place in Wisconsin beside it.
What a year in Fontana-on-Geneva Lake feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 168 frost-free days a year
In half of years the last 32° night comes by April 28 and the first by October 14. Frost and day counts come from NOAA’s station at Delavan Wwtp, WI, 8 miles from the town’s center, at about the same height.
The 2023 USDA map puts Fontana-on-Geneva Lake’s center in zone 5b: the coldest night of a typical winter, averaged over 1991–2020, reaches about −13°. Plant labels use the zone; frost dates tell you when to plant.
Freezing nights by month
Average nights at or below 32°
90° days by month
Average days at 90° or more
About 32 inches of snow a winter
Snow, measured at Harvard, IL, falls mostly in January. Precipitation (rain plus melted snow) adds up to 37 inches a year; June is the wettest month and February the driest. Rain or snow falls on about 120 days a year.
Rain + melted snow by month
Inches of water
Snowfall by month
Inches of snow
Heating and cooling a home in Fontana-on-Geneva Lake
92% of the work is heating, so the furnace matters far more than the air conditioner. Months averaging under 55° run from October through April.
Degree days add up how far each day’s average falls below (heating) or rises above (cooling) 65° over a year. NOAA normals at Delavan Wwtp, WI.
Living with Fontana-on-Geneva Lake’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
168 frost-free days in zone 5b. The last frost comes by Apr 28 in half of years, so many gardeners wait a week or two past that to set out tomatoes. The first fall frost comes by Oct 14.
Months with highs of 62–84° and lows of 40° or more: May, June, July, August and September. 7.6 miles of trails are waiting.
Parks & trails →Of the yearly building losses FEMA expects in Fontana-on-Geneva Lake from natural hazards, river flooding is the largest share (44%); heat waves, cold waves, winter storms and ice storms together are 22%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Fontana-on-Geneva Lake and its neighbors
Every town next door is within a degree of Fontana-on-Geneva Lake in January and July, closer than the 5 km grid can tell apart. Tap a town to see its climate.
Climates most like Fontana-on-Geneva Lake’s, farther away
TownRatings’ own comparison of NOAA 1991–2020 normals, not a NOAA product: places of 5,000+ at least 150 miles away, one per state, closest on January low, July high, precipitation and snow.
| Town | Jan. low | July high | Precip. | Snow |
|---|---|---|---|---|
| Fontana-on-Geneva Lake, WI | 13° | 83° | 37" | 32" |
| Grinnell, IA | 12° | 84° | 38" | 31" |
| Howell, MI | 16° | 82° | 34" | 33" |
| Kendallville, IN | 17° | 83° | 38" | 36" |
| Sayre, PA | 17° | 84° | 37" | 35" |
Temperatures and rain come from NOAA’s 5 km grid, so each town gets its own value. Snow and frost-free days come from the nearest weather station, so neighbors often share them.
Warmer than it used to be
The last 30 years in Fontana-on-Geneva Lake averaged 1.0° warmer than the 1900s. The biggest change is in December (+2.4°).
A smaller shift than in 79% of U.S. towns.
Change by month
The two periods overlap (1991–2000 is in both), which makes the gap a little smaller than it would be between separate periods.
How Fontana-on-Geneva Lake compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Fontana-on-Geneva Lake’s place among Wisconsin’s.
Fontana-on-Geneva Lake weather by month
Highs, lows and precipitation from NOAA’s grid at Fontana-on-Geneva Lake’s center; snow, wet days and snow on the ground from Harvard, IL. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 28° | 13° | 1.7" | 10.0" | 10 | 21 | 11° – 32° |
| February | 32° | 16° | 1.6" | 8.4" | 8 | 16 | 12° – 35° |
| March | 44° | 26° | 2.2" | 4.4" | 10 | 6 | 27° – 49° |
| April | 57° | 36° | 3.8" | 0.7" | 12 | 0 | 38° – 52° |
| May | 69° | 47° | 4.3" | 0.0" | 13 | 0 | 52° – 64° |
| June | 79° | 56° | 4.9" | 0.0" | 11 | 0 | 65° – 73° |
| July | 83° | 61° | 3.8" | 0.0" | 9 | 0 | 67° – 79° |
| August | 81° | 59° | 4.0" | 0.0" | 10 | 0 | 65° – 76° |
| September | 74° | 52° | 3.5" | 0.0" | 9 | 0 | 56° – 67° |
| October | 61° | 40° | 3.0" | 0.0" | 10 | 0 | 46° – 56° |
| November | 46° | 29° | 2.4" | 2.1" | 9 | 2 | 29° – 47° |
| December | 33° | 19° | 2.0" | 6.3" | 9 | 13 | 14° – 36° |
| Year | 57° | 38° | 37.2" | 31.9" | 120 | 57 |
How much a month can swing
A normal is an average. December swings the most: from 1991 to 2020 its average ranged from 14° to 36°. June is the most reliable, staying within 8°.
Where Fontana-on-Geneva Lake’s numbers come from
Normals are 30-year averages, not a forecast. How TownRatings reads climate data →
- Temperatures and precipitation: NOAA’s gridded 1991–2020 normals for the 5 km cell at Fontana-on-Geneva Lake’s center.
- Snow: Harvard, IL.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Delavan Wwtp, WI, 8 miles from the town’s center, at about the same height; the nearest station that passes our checks for distance, height and agreement with the grid.
- Growing zone: USDA Plant Hardiness Zone Map, 2023. USDA Agricultural Research Service and PRISM Group, Oregon State University, prism.oregonstate.edu/phzm, accessed 8 Oct 2026.
- Then and now: NOAA’s gridded normals for 1901–2000 at the same cell.
- Storms and extremes: FEMA National Risk Index (expected annual losses to buildings).
Common questions about Fontana-on-Geneva Lake’s climate
What is the weather like in Fontana-on-Geneva Lake?
A typical July afternoon reaches 83°, a January night drops to 13°, and about 32 inches of snow falls in a normal winter. Colder January nights than 90% of U.S. towns; cooler July afternoons than 74% of U.S. towns.
How cold does it get in Fontana-on-Geneva Lake in winter?
January nights average 13°. About 143 nights a year reach 32° or below and 9 reach 0° or below. In the coldest January of the last 30 years the month averaged 11°.
How much snow does Fontana-on-Geneva Lake get?
About 32 inches in a normal winter at Harvard, IL, most of it in January, with snow on the ground about 57 days a year.
How hot does it get in Fontana-on-Geneva Lake?
July, with a typical high of 83° and a low of 61°. About 13 days a year reach 90° (Delavan Wwtp, WI).
When is the first and last frost in Fontana-on-Geneva Lake?
In half of years the last spring frost (32°) comes by April 28 and the first fall frost by October 14, about 168 frost-free days, at Delavan Wwtp, WI.
What growing zone is Fontana-on-Geneva Lake in?
Zone 5b on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about −13°.
What is the best time of year to visit Fontana-on-Geneva Lake?
By one simple rule (highs of 62–84° and lows of 40° or more), May, June, July, August and September. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is Fontana-on-Geneva Lake getting warmer?
Yes: 1991–2020 averaged 1.0° warmer than 1901–2000 on NOAA’s grid. A smaller shift than 79% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Fontana-on-Geneva Lake.
Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000; USDA/PRISM 2023 hardiness zones; FEMA National Risk Index. Today’s forecast: National Weather Service.