Photo: ArtisticAbode · CC BY-SA 3.0Winter nights in Mount Vernon are colder than in 91% of U.S. towns
In July the day’s top temperature is typically 84°. The seasons are far apart: from a winter night to a summer afternoon the average spans 72°. Precipitation is light here, less than falls on 70% of U.S. towns. Plan time outside from May to October, when highs sit at 62–84°.
A year in Mount Vernon at a glance
Each month’s typical high and low, and what it brings.
What stands out about Mount Vernon’s climate
Compared with towns across the U.S., with Mount Vernon’s place in Iowa beside it.
What a year in Mount Vernon feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 166 frost-free days a year
In half of years the last 32° night comes by April 28 and the first by October 12. Frost and day counts come from NOAA’s station at Cedar Rapids #1, IA, 12 miles from the town’s center, at about the same height.
The 2023 USDA map puts Mount Vernon’s center in zone 5a: the coldest night of a typical winter, averaged over 1991–2020, reaches about −16°. 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 34 inches of snow a winter
Snow, measured at Cedar Rapids #1, IA, falls mostly in January, February and December. Precipitation (rain plus melted snow) adds up to 38 inches a year; June is the wettest month and January the driest. Rain or snow falls on about 118 days a year.
Rain + melted snow by month
Inches of water
Snowfall by month
Inches of snow
Heating and cooling a home in Mount Vernon
87% 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 Cedar Rapids #1, IA.
Living with Mount Vernon’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
166 frost-free days in zone 5a. 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 12.
Months with highs of 62–84° and lows of 40° or more: May, June, July, August, September and October. 1.5 miles of trails are waiting.
Parks & trails →Of the yearly building losses FEMA expects in Mount Vernon from natural hazards, river flooding is the largest share (38%); heat waves, cold waves, winter storms and ice storms together are 14%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Mount Vernon and similar climates
TownRatings has no climate map of the towns around Mount Vernon yet.
Climates most like Mount Vernon’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 |
|---|---|---|---|---|
| Mount Vernon, IA | 12° | 84° | 38" | 34" |
| Woodstock, IL | 14° | 83° | 38" | 35" |
| Delavan, WI | 12° | 83° | 37" | 34" |
| Westville, IN | 16° | 83° | 39" | 34" |
| Sayre, PA | 17° | 84° | 37" | 35" |
Temperatures and precipitation come from NOAA’s 5 km grid; snow and day counts from the stations named on this page.
Warmer than it used to be
The last 30 years in Mount Vernon averaged 1.0° warmer than the 1900s. The biggest change is in December (+2.3°).
A smaller shift than in 80% 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 Mount Vernon compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Mount Vernon’s place among Iowa’s.
Mount Vernon weather by month
Highs, lows and precipitation from NOAA’s grid at Mount Vernon’s center; snow, wet days and snow on the ground from Cedar Rapids #1, IA. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 28° | 12° | 1.1" | 8.7" | 9 | 20 | 11° – 33° |
| February | 33° | 16° | 1.4" | 8.3" | 8 | 16 | 12° – 36° |
| March | 47° | 27° | 2.1" | 4.0" | 10 | 6 | 29° – 52° |
| April | 61° | 38° | 3.8" | 1.5" | 11 | 0 | 41° – 56° |
| May | 72° | 49° | 4.5" | 0.0" | 13 | 0 | 54° – 68° |
| June | 81° | 59° | 5.6" | 0.0" | 12 | 0 | 67° – 74° |
| July | 84° | 63° | 4.4" | 0.0" | 10 | 0 | 67° – 81° |
| August | 82° | 60° | 4.2" | 0.0" | 10 | 0 | 66° – 77° |
| September | 75° | 52° | 3.6" | 0.0" | 9 | 0 | 58° – 68° |
| October | 62° | 40° | 3.0" | 0.6" | 10 | 0 | 46° – 56° |
| November | 47° | 28° | 2.2" | 2.2" | 8 | 1 | 30° – 48° |
| December | 34° | 18° | 1.7" | 9.0" | 9 | 12 | 11° – 35° |
| Year | 59° | 39° | 37.5" | 34.3" | 118 | 56 |
How much a month can swing
A normal is an average. February swings the most: from 1991 to 2020 its average ranged from 12° to 36°. June is the most reliable, staying within 6°.
Where Mount Vernon’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 Mount Vernon’s center.
- Snow: Cedar Rapids #1, IA.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Cedar Rapids #1, IA, 12 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 Mount Vernon’s climate
What is the weather like in Mount Vernon?
A typical July afternoon reaches 84°, a January night drops to 12°, and about 34 inches of snow falls in a normal winter. Colder January nights than 91% of U.S. towns; cooler July afternoons than 63% of U.S. towns.
How cold does it get in Mount Vernon in winter?
January nights average 12°. About 134 nights a year reach 32° or below and 13 reach 0° or below. In the coldest January of the last 30 years the month averaged 11°.
How much snow does Mount Vernon get?
About 34 inches in a normal winter at Cedar Rapids #1, IA, most of it in January, February and December, with snow on the ground about 56 days a year.
How hot does it get in Mount Vernon?
July, with a typical high of 84° and a low of 63°. About 18 days a year reach 90° (Cedar Rapids #1, IA).
When is the first and last frost in Mount Vernon?
In half of years the last spring frost (32°) comes by April 28 and the first fall frost by October 12, about 166 frost-free days, at Cedar Rapids #1, IA.
What growing zone is Mount Vernon in?
Zone 5a on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about −16°.
What is the best time of year to visit Mount Vernon?
By one simple rule (highs of 62–84° and lows of 40° or more), May, June, July, August, September and October. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is Mount Vernon getting warmer?
Yes: 1991–2020 averaged 1.0° warmer than 1901–2000 on NOAA’s grid. A smaller shift than 80% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Mount Vernon.
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.