Grafton, WI climate
Grafton has cold, snowy winters and pleasant summers. A typical July afternoon reaches 80°, a January night drops to 14°, and about 42 inches of snow falls in a normal winter.
NOAA 1991-2020 climate normals Updated once a decadeWhat a year in Grafton feels like
Winter
Spring
Summer
Fall
Grafton weather by month
Average highs, lows, rain and snow for every month, from NOAA’s 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 | 10° – 33° |
| February | 32° | 17° | 1.4" | 10.7" | 7 | 17 | 13° – 34° |
| March | 42° | 25° | 1.9" | 6.0" | 8 | 8 | 25° – 48° |
| April | 53° | 35° | 3.6" | 0.8" | 10 | 1 | 35° – 49° |
| May | 65° | 45° | 3.7" | 0 | 11 | 0 | 49° – 61° |
| June | 75° | 55° | 4.1" | 0 | 10 | 0 | 61° – 70° |
| July | 80° | 61° | 3.5" | 0 | 9 | 0 | 66° – 78° |
| August | 79° | 60° | 3.6" | 0 | 8 | 0 | 64° – 75° |
| September | 71° | 52° | 3.1" | 0 | 8 | 0 | 56° – 67° |
| October | 59° | 41° | 2.7" | 0 | 9 | 0 | 46° – 56° |
| November | 45° | 30° | 2.1" | 0.9" | 8 | 1 | 28° – 46° |
| December | 34° | 20° | 1.8" | 10.7" | 8 | 11 | 14° – 37° |
| Year | 55° | 38° | 32.9" | 42.3" | 103 | 58 |
“Wet days” have at least 0.01" of rain or melted snow. “Snow on ground” counts days with 1" or more. The 30-year range is the coldest and warmest that month’s average temperature got between 1991 and 2020.
Rain and snow in Grafton
Grafton gets 33 inches of rain and melted snow a year. June is the wettest month and February the driest. Rain or snow falls on about 103 days a year. Snow covers the ground about 58 days of the year.
About 158 frost-free days a year
In half of years the last 32° night comes by May 5 and the first one by October 11. That leaves about 158 frost-free days for gardens, shorter than 73% of U.S. towns.
Heating and cooling a home in Grafton
Engineers use “degree days” to estimate how hard a furnace or air conditioner works. In Grafton, 96% of that work is heating and 4% is cooling, so the furnace matters far more than the air conditioner.
Degree days measure how far each day’s average temperature falls below or rises above 65°, added up over a year. Source: NOAA station normals.
Grafton and its neighbors
Grafton borders 6 towns with climate data. January nights across them vary by 2.0°. Cedarburg has both the coldest January nights (13°) and the hottest July afternoons (81°). Grafton’s January low is 14° and its July high 80°.
Temperatures and rain come from NOAA’s 5 km grid, so each town gets its own value.
How Grafton compares
Compared with every U.S. town and city on TownTapestry, each counted once.
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 (+3.2°). The shift is larger than in 58% of U.S. towns.
Change by month1991–2020 average minus 1901–2000 average, at Grafton’s spot on NOAA’s grid
How much a month can swing
A normal is an average, and real years wander around it. December swings the most: between 1991 and 2020 its average temperature ranged from 14° to 37°. June is the most reliable, staying within 9°.
Common questions about Grafton’s climate
What is the coldest month in Grafton?
January, with a typical high of 29° and a low of 14°.
What is the hottest month in Grafton?
July, with a typical high of 80° and a low of 61°. About 3 days a year reach 90°.
How much snow does Grafton get?
About 42 inches in a normal winter, most of it in January.
When is the first frost in Grafton?
In half of years the first 32° night comes by October 11, and the last spring frost by May 5.
What is the rainiest month in Grafton?
June, with 4.1 inches of rain and melted snow. The year totals 33 inches.
Temperatures and rainfall come from NOAA’s gridded climate normals for Grafton itself (about a 3-mile square). Snow, frost dates and day counts come from NOAA’s weather station at Port Washington, WI (5 mi, snow) and Saukville WWTP, WI (2 mi, frost, heat and degree days). Normals are 30-year averages, not a forecast. Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000.