Photo: Gepard12 · Public domainWinter nights in Williams Bay are colder than in 90% of U.S. towns
July afternoons average 83°. Summers stay cool: July afternoons here are cooler than in 74% of U.S. towns. Compared with 1901–2000, the average now sits 1.0° higher. The frost-free window for a garden runs roughly April 25 to October 21.
A year in Williams Bay at a glance
Each month’s typical high and low, and what it brings.
What stands out about Williams Bay’s climate
Compared with towns across the U.S., with Williams Bay’s place in Wisconsin beside it.
What a year in Williams Bay feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 179 frost-free days a year
In half of years the last 32° night comes by April 25 and the first by October 21. Frost and day counts come from NOAA’s station at Lake Geneva Wwtp, WI, 6 miles from the town’s center, at about the same height.
The 2023 USDA map puts Williams Bay’s center in zone 5b: the coldest night of a typical winter, averaged over 1991–2020, reaches about −12°. 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 Williams Bay
88% 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 Lake Geneva Wwtp, WI.
Living with Williams Bay’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
179 frost-free days in zone 5b. The last frost comes by Apr 25 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 21.
Months with highs of 62–84° and lows of 40° or more: May, June, July, August and September. 9.5 miles of trails are waiting.
Parks & trails →Of the yearly building losses FEMA expects in Williams Bay from natural hazards, river flooding is the largest share (37%); heat waves, cold waves, winter storms and ice storms together are 24%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Williams Bay and its neighbors
Every town next door is within a degree of Williams Bay in January and July, closer than the 5 km grid can tell apart. Tap a town to see its climate.
Climates most like Williams Bay’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 |
|---|---|---|---|---|
| Williams Bay, 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 Williams Bay 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 Williams Bay compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Williams Bay’s place among Wisconsin’s.
Williams Bay weather by month
Highs, lows and precipitation from NOAA’s grid at Williams Bay’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 Williams Bay’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 Williams Bay’s center.
- Snow: Harvard, IL.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Lake Geneva Wwtp, WI, 6 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 Williams Bay’s climate
What is the weather like in Williams Bay?
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 Williams Bay in winter?
January nights average 13°. About 136 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 Williams Bay 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 Williams Bay?
July, with a typical high of 83° and a low of 61°. About 21 days a year reach 90° (Lake Geneva Wwtp, WI).
When is the first and last frost in Williams Bay?
In half of years the last spring frost (32°) comes by April 25 and the first fall frost by October 21, about 179 frost-free days, at Lake Geneva Wwtp, WI.
What growing zone is Williams Bay in?
Zone 5b on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about −12°.
What is the best time of year to visit Williams Bay?
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 Williams Bay 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 Williams Bay.
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.