San Mar, MD climate
San Mar has chilly winters and warm summers. A typical July afternoon reaches 87°, a January night drops to 23°, and about 28 inches of snow falls in a normal winter.
NOAA 1991-2020 climate normals Updated once a decadeWhat a year in San Mar feels like
Winter
Spring
Summer
Fall
San Mar weather by month
Average highs, lows, rain and snow for every month, from NOAA’s 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 40° | 23° | 2.9" | 8.7" | 9 | 6 | 23° – 39° |
| February | 44° | 25° | 2.4" | 8.8" | 8 | 8 | 24° – 43° |
| March | 53° | 32° | 3.5" | 4.4" | 10 | 3 | 37° – 51° |
| April | 65° | 41° | 3.6" | 0.2" | 11 | 0 | 49° – 59° |
| May | 74° | 51° | 4.2" | 0 | 13 | 0 | 58° – 68° |
| June | 83° | 60° | 3.7" | 0 | 11 | 0 | 67° – 74° |
| July | 87° | 64° | 4.0" | 0 | 11 | 0 | 71° – 79° |
| August | 85° | 63° | 3.4" | 0 | 10 | 0 | 69° – 77° |
| September | 78° | 55° | 4.4" | 0 | 9 | 0 | 64° – 71° |
| October | 66° | 44° | 3.3" | 0.1" | 9 | 0 | 52° – 62° |
| November | 54° | 34° | 3.0" | 0.8" | 8 | 0 | 38° – 50° |
| December | 44° | 28° | 3.5" | 4.5" | 9 | 3 | 26° – 46° |
| Year | 64° | 43° | 41.8" | 27.5" | 117 | 21 |
“Wet days” have at least 0.01" of rain or melted snow. “Snow on ground” counts days with 1" or more. The 30-year range is the coldest and warmest that month’s average temperature got between 1991 and 2020.
Rain and snow in San Mar
San Mar gets 42 inches of rain and melted snow a year. September is the wettest month and February the driest. Rain or snow falls on about 117 days a year. Snow covers the ground about 21 days of the year.
About 199 frost-free days a year
In half of years the last 32° night comes by April 11 and the first one by October 28. That leaves about 199 frost-free days for gardens, longer than 72% of U.S. towns.
Heating and cooling a home in San Mar
Engineers use “degree days” to estimate how hard a furnace or air conditioner works. In San Mar, 82% of that work is heating and 18% is cooling, so the furnace matters far more than the air conditioner.
Degree days measure how far each day’s average temperature falls below or rises above 65°, added up over a year. Source: NOAA station normals.
How San Mar compares
Compared with every U.S. town and city on TownTapestry, each counted once.
Warmer than it used to be
The last 30 years in San Mar averaged 1.6° warmer than the 1900s. The biggest change is in December (+2.8°). The shift is larger than in 76% of U.S. towns.
Change by month1991–2020 average minus 1901–2000 average, at San Mar’s spot on NOAA’s grid
How much a month can swing
A normal is an average, and real years wander around it. December swings the most: between 1991 and 2020 its average temperature ranged from 26° to 46°. June is the most reliable, staying within 7°.
Common questions about San Mar’s climate
What is the coldest month in San Mar?
January, with a typical high of 40° and a low of 23°.
What is the hottest month in San Mar?
July, with a typical high of 87° and a low of 64°. About 32 days a year reach 90°.
How much snow does San Mar get?
About 28 inches in a normal winter, most of it in February.
When is the first frost in San Mar?
In half of years the first 32° night comes by October 28, and the last spring frost by April 11.
What is the rainiest month in San Mar?
September, with 4.4 inches of rain and melted snow. The year totals 42 inches.
Temperatures and rainfall come from NOAA’s gridded climate normals for San Mar itself (about a 3-mile square). Snow, frost dates and day counts come from NOAA’s weather station at Emmitsburg 2 Se, MD (21 mi, snow) and Hagerstown 1 E, MD (7 mi, frost, heat and degree days). Normals are 30-year averages, not a forecast. Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000.