Photo: Ken Lund from Reno, Nevada, USA · CC BY-SA 2.0The climate in Severn sits close to the middle of U.S. towns
The coldest hours of a January night bottom out at 26° on average. From frosty January to warm July, readings climb 63°. Its July heat outdoes that of 70% of U.S. towns. If you like long walks, April, May, September and October offer highs of 67–80°.
A year in Severn at a glance
Each month’s typical high and low, and what it brings.
What stands out about Severn’s climate
Compared with towns across the U.S., with Severn’s place in Maryland beside it.
What a year in Severn feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 204 frost-free days a year
In half of years the last 32° night comes by April 10 and the first by October 31. Frost and day counts come from NOAA’s station at Baltimore Wash International Airport, 2.2 miles from the city’s center point, at about the same height.
The 2023 USDA map puts Severn’s center in zone 7b: the coldest night of a typical winter, averaged over 1991–2020, reaches about 7°. 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 19 inches of snow a winter
Snow, measured at Baltimore Wash International Airport, falls mostly in February. Precipitation (rain plus melted snow) adds up to 46 inches a year; July is the wettest month and February the driest. Rain or snow falls on about 121 days a year.
Rain + melted snow by month
Inches of water
Snowfall by month
Inches of snow
Heating and cooling a home in Severn
77% of the work is heating. Months averaging under 55° run from November through March.
Degree days add up how far each day’s average falls below (heating) or rises above (cooling) 65° over a year. NOAA normals at Baltimore Wash International Airport.
Living with Severn’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
204 frost-free days in zone 7b. The last frost comes by Apr 10 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 31.
Months with highs of 62–84° and lows of 40° or more: April, May, September and October. 4.8 miles of trails are waiting.
Parks & trails →Of the yearly building losses FEMA expects in Severn from natural hazards, river flooding is the largest share (48%); heat waves, cold waves, winter storms and ice storms together are 17%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Severn and its neighbors
Every town next door is within a degree of Severn in January and July, closer than the 5 km grid can tell apart. Tap a town to see its climate.
Climates most like Severn’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 |
|---|---|---|---|---|
| Severn, MD | 26° | 89° | 46" | 19" |
| Salem, VA | 27° | 88° | 44" | 18" |
| Henderson, KY | 25° | 88° | 48" | 12" |
| Rolla, MO | 23° | 88° | 44" | 17" |
| Du Quoin, IL | 24° | 88° | 46" | 12" |
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 Severn averaged 1.9° warmer than the 1900s. The biggest change is in December (+2.9°).
A bigger shift than in 83% 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 Severn compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Severn’s place among Maryland’s.
Severn weather by month
Highs, lows and precipitation from NOAA’s grid at Severn’s center; snow, wet days and snow on the ground from Baltimore Wash International Airport. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 43° | 26° | 3.1" | 6.4" | 10 | 4 | 27° – 42° |
| February | 47° | 27° | 2.8" | 7.5" | 9 | 5 | 26° – 45° |
| March | 55° | 34° | 4.0" | 2.8" | 11 | 2 | 39° – 54° |
| April | 67° | 44° | 3.5" | 0.0" | 11 | 0 | 52° – 61° |
| May | 76° | 54° | 4.1" | 0.0" | 12 | 0 | 60° – 71° |
| June | 84° | 63° | 4.3" | 0.0" | 11 | 0 | 70° – 78° |
| July | 89° | 68° | 4.5" | 0.0" | 10 | 0 | 73° – 82° |
| August | 86° | 66° | 4.4" | 0.0" | 10 | 0 | 72° – 79° |
| September | 80° | 59° | 4.5" | 0.0" | 9 | 0 | 66° – 73° |
| October | 68° | 47° | 4.1" | 0.0" | 9 | 0 | 54° – 64° |
| November | 57° | 37° | 3.2" | 0.1" | 9 | 0 | 41° – 52° |
| December | 48° | 30° | 3.8" | 2.5" | 10 | 2 | 30° – 50° |
| Year | 67° | 46° | 46.1" | 19.3" | 121 | 13 |
How much a month can swing
A normal is an average. December swings the most: from 1991 to 2020 its average ranged from 30° to 50°. September is the most reliable, staying within 7°.
Where Severn’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 Severn’s center.
- Snow: Baltimore Wash International Airport.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Baltimore Wash International Airport, 2.2 miles from the city’s center point, 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 Severn’s climate
What is the weather like in Severn?
A typical July afternoon reaches 89°, a January night drops to 26°, and about 19 inches of snow falls in a normal winter. Milder January nights than 66% of U.S. towns; hotter July afternoons than 70% of U.S. towns.
How cold does it get in Severn in winter?
January nights average 26°. About 93 nights a year reach 32° or below. In the coldest January of the last 30 years the month averaged 27°.
How much snow does Severn get?
About 19 inches in a normal winter at Baltimore Wash International Airport, most of it in February, with snow on the ground about 13 days a year.
How hot does it get in Severn?
July, with a typical high of 89° and a low of 68°. About 34 days a year reach 90° and 1 reach 100° (Baltimore Wash International Airport).
When is the first and last frost in Severn?
In half of years the last spring frost (32°) comes by April 10 and the first fall frost by October 31, about 204 frost-free days, at Baltimore Wash International Airport.
What growing zone is Severn in?
Zone 7b on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about 7°.
What is the best time of year to visit Severn?
By one simple rule (highs of 62–84° and lows of 40° or more), April, May, September and October. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is Severn getting warmer?
Yes: 1991–2020 averaged 1.9° warmer than 1901–2000 on NOAA’s grid. A bigger shift than 83% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Severn.
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.