Updated October 2026
Antietam National Battlefield Weather by Month
Antietam National Battlefield is warmest in July, when the nearest NOAA climate station averages a high of 86°F and a low of 62°F, and coldest in January, with an average high of 41°F and an average low of 21°F. May is the wettest month, with about 4.6 inches of precipitation.
These figures are NOAA's 1991–2020 climate normals, the 30-year average for each calendar month, from the nearest long-record weather station, 4.9 miles from the park's reference point. A single station cannot describe a whole park: temperatures elsewhere in Antietam National Battlefield can differ from these, particularly with elevation.
Warmest month
Jul
86°F avg high
Coldest month
Jan
21°F avg low
Wettest month
May
4.6 in avg
Longest days
Jun
14.8 h of daylight
Average weather at Antietam by month
| Month | Avg high | Avg low | Precipitation | Daylight |
|---|---|---|---|---|
| January | 41°F | 21°F | 3.1 in | 9.5 h |
| February | 44°F | 23°F | 2.4 in | 10.5 h |
| March | 53°F | 29°F | 3.7 in | 11.7 h |
| April | 65°F | 39°F | 3.6 in | 13.0 h |
| May | 74°F | 49°F | 4.6 in | 14.2 h |
| June | 82°F | 58°F | 4.2 in | 14.8 h |
| July | 86°F | 62°F | 4.3 in | 14.5 h |
| August | 85°F | 61°F | 3.3 in | 13.6 h |
| September | 78°F | 54°F | 4.4 in | 12.2 h |
| October | 67°F | 42°F | 3.4 in | 10.9 h |
| November | 56°F | 32°F | 3.1 in | 9.8 h |
| December | 45°F | 25°F | 3.5 in | 9.2 h |
| Year total | 43.6 in |
NOAA 1991–2020 climate normals from station USC00188207, 4.9 miles from the park's reference point. Daylight is the monthly average, computed from the park's latitude. Each month links to how crowded Antietam is at that time of year.
Antietam weather by season
Winter: December to February
Average highs bottom out at 41°F in January, between 45°F in December and 44°F in February, with average lows between 21°F and 25°F. The average low is at or below freezing in all three months. Together the three months average 9 inches of precipitation, about 21% of the yearly total and less than in any other season. Daylight is at its shortest, about 9.2 hours in December.
Spring: March to May
Average highs climb from 53°F in March to 74°F in May, with average lows between 29°F and 49°F. The average low is at or below freezing in March. Together the three months average 11.9 inches of precipitation, about 27% of the yearly total and more than in any other season. Daylight lengthens from about 11.7 hours in March to 14.2 in May.
Summer: June to August
Average highs peak at 86°F in July, between 82°F in June and 85°F in August, with average lows between 58°F and 62°F. Together the three months average 11.8 inches of precipitation, about 27% of the yearly total. Daylight is at its longest, about 14.8 hours in June.
Fall: September to November
Average highs fall from 78°F in September to 56°F in November, with average lows between 32°F and 54°F. The average low is at or below freezing in November. Together the three months average 10.9 inches of precipitation, about 25% of the yearly total. Daylight shortens from about 12.2 hours in September to 9.8 in November.
What the National Park Service says about the weather
The weather is fairly mild. Summers can be very warm and humid and winters cold and snowy. We have four distinct seasons with the fall and spring being the best times to visit the battlefield.
Weather description courtesy of the National Park Service — official park site.
Today's forecast for Antietam
Averages describe a typical month, not this week. For current conditions and the seven-day outlook, the National Weather Service issues a forecast for the park's reference point at 39.47°N, 77.74°W. It covers that one spot, so other elevations in the park can differ from it, as they do from the averages above.
National Weather Service forecast for Antietam National Battlefield →
Weather and crowds together
July is both the warmest month and the busiest, with about 2.0× the visitors of the park's average month. January is the quietest. To see those crowds set against the weather for all twelve months, read the best time to visit Antietam National Battlefield. For hotels, cabins and rentals close to the park, see where to stay near Antietam.
Where to stay near Antietam
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Top-rated places to stay near Antietam
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Frequently Asked Questions
July is the warmest month at Antietam National Battlefield, with an average high of 86°F and an average low of 62°F. That is the 1991–2020 average at the nearest long-record NOAA station, 4.9 miles from the park's reference point. Temperatures inside the park can differ, particularly with elevation.
January is the coldest month at Antietam National Battlefield, with an average low of 21°F and an average high of 41°F, based on NOAA 1991–2020 climate normals.
May is the wettest month, with about 4.6 inches of precipitation. February is the driest, at about 2.4 inches. The station records about 43.6 inches of precipitation in an average year.
Daylight at Antietam National Battlefield runs from about 9.2 hours a day in December to about 14.8 hours in June, computed from the park's latitude.
Weather at nearby parks
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Keep exploring
Sources: NOAA NCEI U.S. Climate Normals 1991–2020 (station USC00188207), daylight computed from latitude, weather description from the National Park Service, crowd levels from National Park Service Visitor Use Statistics (1979–2025). Updated 2026-10-11. Lodging results are provided by Stay22; WhenToVisitParks may earn a commission from bookings, at no extra cost to you.