Grafton has cold, snowy winters and pleasant summers
A typical July afternoon reaches 82°, a January night drops to 7°, and about 48 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
Read from where Grafton sits among Iowa’s towns. The page puts what stands out first.
48 inches of snow, 36 of rain and melt
June is the wettest month and January the driest. Rain or snow falls on about 91 days a year.
Rain + melted snow by month
Inches of water
Snowfall by month
Inches of snow
What a year in Grafton feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 161 frost-free days a year
In half of years the last 32° night comes by April 29 and the first by October 7.
Freezing nights by month
Average nights at or below 32°
90° days by month
Average days at 90° or more
Living with Grafton’s climate
What the numbers mean for a garden, a driveway, a furnace and a free afternoon.
161 frost-free days. The last frost comes by Apr 29 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 7.
About 48" a winter over 13 days with an inch or more, most in December. Snow covers the ground about 90 days a year.
Months averaging under 55° run from October through April. Heating is 93% of the year’s heating-and-cooling load.
About 9 days a year reach 90°, and July afternoons average 82°.
The nicest months are May, June, July, August and September.
Parks & trails →Normals are averages. Ice storms, nor’easters, floods and heat waves are on the natural hazards page.
Natural hazards →Warmer than it used to be
The last 30 years in Grafton averaged 0.9° warmer than the 1900s. The biggest change is in December (+2.9°).
A smaller shift than in 76% of U.S. towns.
Change by month
How Grafton compares
Against every U.S. town on TownTapestry, each counted once, with its place in Iowa.
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 | 23° | 7° | 0.9" | 10.1" | 6 | 26 | 5° – 29° |
| February | 28° | 12° | 1.1" | 11.3" | 5 | 26 | 9° – 31° |
| March | 41° | 24° | 2.0" | 6.4" | 6 | 15 | 25° – 49° |
| April | 57° | 35° | 3.9" | 3.5" | 10 | 1 | 35° – 53° |
| May | 69° | 47° | 5.0" | 0.8" | 11 | 0 | 52° – 65° |
| June | 79° | 58° | 5.5" | 0 | 11 | 0 | 64° – 73° |
| July | 82° | 61° | 4.7" | 0 | 8 | 0 | 65° – 77° |
| August | 79° | 58° | 4.0" | 0 | 8 | 0 | 64° – 74° |
| September | 73° | 50° | 3.4" | 0 | 8 | 0 | 55° – 67° |
| October | 59° | 38° | 2.6" | 0.2" | 8 | 0 | 43° – 54° |
| November | 43° | 26° | 1.7" | 2.7" | 5 | 3 | 25° – 46° |
| December | 29° | 14° | 1.3" | 12.7" | 6 | 18 | 7° – 31° |
| Year | 55° | 36° | 36.0" | 47.7" | 91 | 90 |
Heating and cooling a home in Grafton
93% of the work is heating, so the furnace matters far more than the air conditioner.
Degree days add up how far each day’s average falls below (heating) or rises above (cooling) 65° over a year. Source: NOAA station normals.
How much a month can swing
A normal is an average. March swings the most: from 1991 to 2020 its average ranged from 25° to 49°. June is the most reliable, staying within 8°.
Common questions about Grafton’s climate
What is the coldest month in Grafton?
January, with a typical high of 23° and a low of 7°.
What is the hottest month in Grafton?
July, with a typical high of 82° and a low of 61°. About 9 days a year reach 90°.
How much snow does Grafton get?
About 48 inches in a normal winter, most of it in December.
When is the first frost in Grafton?
In half of years the first 32° night comes by October 7, and the last spring frost by April 29.
What is the rainiest month in Grafton?
June, with 5.5 inches of rain and melted snow. The year totals 36 inches.
Neighbors talk weather
Gardens, snow, and the best days of the year in Grafton.
Your answer becomes a post in Town Square.
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 St Ansgar, IA (8 mi, snow) and Mason City, IA (13 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. Today’s forecast: National Weather Service.