Milwaukee Falls Lime Company · Photo: Sallyajackson · CC BY-SA 3.0Grafton’s winters are colder and snowier than most of the U.S.
A typical July afternoon reaches 80°, a January night drops to 14°, and about 42 inches of snow falls in a normal winter.
A year in Grafton at a glance
Each month’s typical high and low, and what it brings.
What stands out about Grafton’s climate
Compared with towns across the U.S., with Grafton’s place in Wisconsin beside it.
What a year in Grafton feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 182 frost-free days a year
In half of years the last 32° night comes by April 23 and the first by October 24. Frost and day counts come from NOAA’s station at Grafton Wwtp, WI, 1.2 miles from the town’s center, at about the same height.
The 2023 USDA map puts Grafton’s center in zone 6a: the coldest night of a typical winter, averaged over 1991–2020, reaches about −9°. 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 42 inches of snow a winter
Snow, measured at Port Washington, WI, falls mostly in January. Precipitation (rain plus melted snow) adds up to 33 inches a year; June is the wettest month and February the driest. Rain or snow falls on about 103 days a year.
Rain + melted snow by month
Inches of water
Snowfall by month
Inches of snow
Heating and cooling a home in Grafton
92% of the work is heating, so the furnace matters far more than the air conditioner. Months averaging under 55° run from October through May.
Degree days add up how far each day’s average falls below (heating) or rises above (cooling) 65° over a year. NOAA normals at Grafton Wwtp, WI.
Living with Grafton’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
182 frost-free days in zone 6a. The last frost comes by Apr 23 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 24.
Months with highs of 62–84° and lows of 40° or more: May, June, July, August and September. 1.9 miles of trails are waiting.
Parks & trails →Of the yearly building losses FEMA expects in Grafton from natural hazards, river flooding is the largest share (51%); heat waves, cold waves, winter storms and ice storms together are 31%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Grafton and its neighbors
Cedarburg has the coldest January nights next door (13°, 2° colder). Differences under a degree are within what the 5 km grid can tell apart. Tap a town to see its climate.
Climates most like Grafton’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 |
|---|---|---|---|---|
| Grafton, WI | 14° | 80° | 33" | 42" |
| Erwin, NY | 15° | 81° | 36" | 47" |
| Milford, MI | 15° | 82° | 33" | 36" |
| Colchester, VT | 10° | 81° | 38" | 50" |
| Asbury, IA | 11° | 83° | 38" | 43" |
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 Grafton averaged 1.3° warmer than the 1900s. The biggest change is in December (+3.1°).
A smaller shift than in 53% 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 Grafton compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Grafton’s place among Wisconsin’s.
Grafton weather by month
Highs, lows and precipitation from NOAA’s grid at Grafton’s center; snow, wet days and snow on the ground from Port Washington, WI. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 29° | 14° | 1.6" | 13.2" | 8 | 21 | 11° – 33° |
| February | 32° | 17° | 1.5" | 10.7" | 7 | 17 | 13° – 34° |
| March | 42° | 26° | 1.9" | 6.0" | 8 | 8 | 26° – 48° |
| April | 53° | 35° | 3.6" | 0.8" | 10 | 1 | 35° – 50° |
| May | 65° | 45° | 3.7" | 0.0" | 11 | 0 | 49° – 60° |
| June | 75° | 55° | 4.2" | 0.0" | 10 | 0 | 61° – 70° |
| July | 80° | 61° | 3.5" | 0.0" | 9 | 0 | 66° – 78° |
| August | 79° | 60° | 3.6" | 0.0" | 8 | 0 | 65° – 75° |
| September | 72° | 53° | 3.1" | 0.0" | 8 | 0 | 56° – 67° |
| October | 59° | 41° | 2.7" | 0.0" | 9 | 0 | 46° – 56° |
| November | 45° | 30° | 2.1" | 0.9" | 8 | 1 | 29° – 46° |
| December | 34° | 20° | 1.8" | 10.7" | 8 | 11 | 15° – 38° |
| Year | 55° | 38° | 33.2" | 42.3" | 103 | 58 |
How much a month can swing
A normal is an average. December swings the most: from 1991 to 2020 its average ranged from 15° to 38°. June is the most reliable, staying within 9°.
Where Grafton’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 Grafton’s center.
- Snow: Port Washington, WI.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Grafton Wwtp, WI, 1.2 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 Grafton’s climate
What is the weather like in Grafton?
A typical July afternoon reaches 80°, a January night drops to 14°, and about 42 inches of snow falls in a normal winter. Colder January nights than 86% of U.S. towns; cooler July afternoons than 91% of U.S. towns.
How cold does it get in Grafton in winter?
January nights average 14°. About 134 nights a year reach 32° or below and 7 reach 0° or below. In the coldest January of the last 30 years the month averaged 11°.
How much snow does Grafton get?
About 42 inches in a normal winter at Port Washington, WI, most of it in January, with snow on the ground about 58 days a year.
How hot does it get in Grafton?
July, with a typical high of 80° and a low of 61°. About 6 days a year reach 90° (Grafton Wwtp, WI).
When is the first and last frost in Grafton?
In half of years the last spring frost (32°) comes by April 23 and the first fall frost by October 24, about 182 frost-free days, at Grafton Wwtp, WI.
What growing zone is Grafton in?
Zone 6a on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about −9°.
What is the best time of year to visit Grafton?
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 Grafton getting warmer?
Yes: 1991–2020 averaged 1.3° warmer than 1901–2000 on NOAA’s grid. A smaller shift than 53% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Grafton.
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.