Charlestown Historic District · Photo: Smallbones · CC BY-SA 3.0A middle-of-the-road climate: Charlestown is close to most U.S. towns on every count
On a normal July day the thermometer tops out near 87°. Precipitation is plentiful here, more than falls on 70% of U.S. towns. Since 1901–2000, the year has warmed by 1.8°, most of all in December. The heating season runs November to March: each of those months averages under 50°.
A year in Charlestown at a glance
Each month’s typical high and low, and what it brings.
What stands out about Charlestown’s climate
Compared with towns across the U.S., with Charlestown’s place in Maryland beside it.
What a year in Charlestown feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 217 frost-free days a year
In half of years the last 32° night comes by April 3 and the first by November 6. Frost and day counts come from NOAA’s station at Conowingo Dam, MD, 11 miles from the town’s center, at about the same height.
The 2023 USDA map puts Charlestown’s center in zone 7b: the coldest night of a typical winter, averaged over 1991–2020, reaches about 6°. 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 20 inches of snow a winter
Snow, measured at Wilmington New Castle Co Airport, falls mostly in February. Precipitation (rain plus melted snow) adds up to 47 inches a year; July is the wettest month and February the driest. Rain or snow falls on about 122 days a year.
Rain + melted snow by month
Inches of water
Snowfall by month
Inches of snow
Heating and cooling a home in Charlestown
79% of the work is heating. Months averaging under 55° run from November 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 Conowingo Dam, MD.
Living with Charlestown’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
217 frost-free days in zone 7b. The last frost comes by Apr 3 in half of years, so many gardeners wait a week or two past that to set out tomatoes. The first fall frost comes by Nov 6.
Months with highs of 62–84° and lows of 40° or more: April, May, June, September and October. 1.1 miles of trails are waiting.
Parks & trails →Of the yearly building losses FEMA expects in Charlestown from natural hazards, river flooding is the largest share (51%); heat waves, cold waves, winter storms and ice storms together are 15%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Charlestown and similar climates
TownRatings has no climate map of the towns around Charlestown yet.
Climates most like Charlestown’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 |
|---|---|---|---|---|
| Charlestown, MD | 26° | 87° | 47" | 20" |
| Cave Spring, VA | 27° | 87° | 45" | 18" |
| Cynthiana, KY | 24° | 87° | 48" | 16" |
| Forestville, OH | 23° | 86° | 45" | 23" |
| Lawrenceburg, IN | 23° | 86° | 45" | 23" |
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 Charlestown averaged 1.8° warmer than the 1900s. The biggest change is in December (+3.3°).
A bigger shift than in 77% 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 Charlestown compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Charlestown’s place among Maryland’s.
Charlestown weather by month
Highs, lows and precipitation from NOAA’s grid at Charlestown’s center; snow, wet days and snow on the ground from Wilmington New Castle Co Airport. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 41° | 26° | 3.3" | 6.1" | 11 | 5 | 25° – 41° |
| February | 44° | 27° | 2.7" | 7.8" | 10 | 7 | 24° – 42° |
| March | 52° | 34° | 4.2" | 3.1" | 11 | 3 | 37° – 52° |
| April | 64° | 43° | 3.7" | 0.1" | 11 | 0 | 49° – 58° |
| May | 73° | 53° | 3.8" | 0.0" | 12 | 0 | 59° – 69° |
| June | 82° | 63° | 4.4" | 0.0" | 11 | 0 | 69° – 77° |
| July | 87° | 68° | 4.8" | 0.0" | 10 | 0 | 73° – 81° |
| August | 85° | 66° | 4.3" | 0.0" | 9 | 0 | 71° – 78° |
| September | 78° | 59° | 4.7" | 0.0" | 9 | 0 | 66° – 72° |
| October | 67° | 48° | 4.0" | 0.0" | 9 | 0 | 53° – 64° |
| November | 56° | 38° | 3.2" | 0.2" | 9 | 0 | 41° – 51° |
| December | 46° | 30° | 4.0" | 2.9" | 11 | 2 | 31° – 48° |
| Year | 65° | 46° | 47.0" | 20.2" | 122 | 17 |
How much a month can swing
A normal is an average. February swings the most: from 1991 to 2020 its average ranged from 24° to 42°. September is the most reliable, staying within 6°.
Where Charlestown’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 Charlestown’s center.
- Snow: Wilmington New Castle Co Airport.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Conowingo Dam, MD, 11 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 Charlestown’s climate
What is the weather like in Charlestown?
A typical July afternoon reaches 87°, a January night drops to 26°, and about 20 inches of snow falls in a normal winter. Milder January nights than 64% of U.S. towns; hotter July afternoons than 60% of U.S. towns.
How cold does it get in Charlestown in winter?
January nights average 26°. About 106 nights a year reach 32° or below. In the coldest January of the last 30 years the month averaged 25°.
How much snow does Charlestown get?
About 20 inches in a normal winter at Wilmington New Castle Co Airport, most of it in February, with snow on the ground about 17 days a year.
How hot does it get in Charlestown?
July, with a typical high of 87° and a low of 68°. About 37 days a year reach 90° and 3 reach 100° (Conowingo Dam, MD).
When is the first and last frost in Charlestown?
In half of years the last spring frost (32°) comes by April 3 and the first fall frost by November 6, about 217 frost-free days, at Conowingo Dam, MD.
What growing zone is Charlestown in?
Zone 7b on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about 6°.
What is the best time of year to visit Charlestown?
By one simple rule (highs of 62–84° and lows of 40° or more), April, May, June, September and October. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is Charlestown getting warmer?
Yes: 1991–2020 averaged 1.8° warmer than 1901–2000 on NOAA’s grid. A bigger shift than 77% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Charlestown.
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.