Mount Vernon sits near the bottom of U.S. towns for winter warmth
On a normal July day the thermometer tops out near 87°. Its yearly precipitation falls short of 87% of U.S. towns. Warming shows here too: 0.8° more than in 1901–2000, led by January. The frost-free window for a garden runs roughly April 27 to October 11.
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 South Dakota 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 167 frost-free days a year
In half of years the last 32° night comes by April 27 and the first by October 11. Frost and day counts come from NOAA’s station at Mitchell, SD, 10 miles from the town’s center, 110 ft lower.
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 −18°. 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 41 inches of snow a winter
Snow, measured at Mitchell, SD, falls mostly in December. Precipitation (rain plus melted snow) adds up to 25 inches a year; June is the wettest month and January the driest. Rain or snow falls on about 89 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
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 Mitchell, SD.
Living with Mount Vernon’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
167 frost-free days in zone 5a. The last frost comes by Apr 27 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 11.
Months with highs of 62–84° and lows of 40° or more: May, June, August and September.
Parks & trails →Of the yearly building losses FEMA expects in Mount Vernon from natural hazards, river flooding is the largest share (39%); heat waves, cold waves, winter storms and ice storms together are 18%. 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, SD | 8° | 87° | 25" | 41" |
| Schuyler, NE | 13° | 87° | 29" | 36" |
| Cherokee, IA | 8° | 84° | 31" | 38" |
| Redwood Falls, MN | 6° | 83° | 29" | 44" |
| Air Force Academy, CO | 14° | 84° | 21" | 55" |
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 0.8° warmer than the 1900s. The biggest change is in January (+2.9°).
A smaller shift than in 88% 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 South Dakota’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 Mitchell, SD. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 28° | 8° | 0.5" | 5.6" | 5 | 25 | 8° – 33° |
| February | 33° | 12° | 0.9" | 8.3" | 6 | 18 | 7° – 34° |
| March | 46° | 23° | 1.3" | 5.8" | 7 | 9 | 23° – 49° |
| April | 59° | 34° | 2.8" | 6.0" | 9 | 3 | 36° – 53° |
| May | 70° | 46° | 3.6" | 0.0" | 12 | 0 | 52° – 65° |
| June | 81° | 57° | 3.8" | 0.0" | 11 | 0 | 65° – 74° |
| July | 87° | 62° | 2.9" | 0.0" | 7 | 0 | 66° – 81° |
| August | 84° | 60° | 2.8" | 0.0" | 8 | 0 | 66° – 76° |
| September | 76° | 50° | 2.7" | 0.0" | 7 | 0 | 57° – 69° |
| October | 61° | 37° | 2.0" | 0.6" | 8 | 0 | 42° – 53° |
| November | 45° | 23° | 0.9" | 4.1" | 4 | 3 | 24° – 44° |
| December | 32° | 13° | 0.7" | 10.2" | 6 | 20 | 9° – 29° |
| Year | 58° | 35° | 24.9" | 40.6" | 89 | 78 |
How much a month can swing
A normal is an average. February swings the most: from 1991 to 2020 its average ranged from 7° to 34°. June is the most reliable, staying within 9°.
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: Mitchell, SD.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Mitchell, SD, 10 miles from the town’s center, 110 ft lower; 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 87°, a January night drops to 8°, and about 41 inches of snow falls in a normal winter. Colder January nights than 96% of U.S. towns; hotter July afternoons than 60% of U.S. towns.
How cold does it get in Mount Vernon in winter?
January nights average 8°. About 152 nights a year reach 32° or below and 21 reach 0° or below. In the coldest January of the last 30 years the month averaged 8°.
How much snow does Mount Vernon get?
About 41 inches in a normal winter at Mitchell, SD, most of it in December, with snow on the ground about 78 days a year.
How hot does it get in Mount Vernon?
July, with a typical high of 87° and a low of 62°. About 30 days a year reach 90° and 2 reach 100° (Mitchell, SD).
When is the first and last frost in Mount Vernon?
In half of years the last spring frost (32°) comes by April 27 and the first fall frost by October 11, about 167 frost-free days, at Mitchell, SD.
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 −18°.
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, August and September. 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 0.8° warmer than 1901–2000 on NOAA’s grid. A smaller shift than 88% 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.