Chantilly, VA climate
Chantilly has chilly winters and warm summers. A typical July afternoon reaches 87°, a January night drops to 26°, and about 21 inches of snow falls in a normal winter.
NOAA 1991-2020 climate normals Updated once a decadeWhat a year in Chantilly feels like
Winter
Spring
Summer
Fall
Chantilly 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 | 43° | 26° | 2.9" | 6.9" | 10 | 4 | 26° – 41° |
| February | 46° | 27° | 2.5" | 7.0" | 9 | 5 | 26° – 44° |
| March | 55° | 34° | 3.5" | 3.9" | 11 | 2 | 38° – 54° |
| April | 67° | 44° | 3.3" | 0.1" | 11 | 0 | 51° – 61° |
| May | 75° | 53° | 4.3" | 0 | 13 | 0 | 59° – 70° |
| June | 83° | 62° | 4.1" | 0 | 11 | 0 | 68° – 77° |
| July | 87° | 67° | 4.2" | 0 | 11 | 0 | 73° – 81° |
| August | 86° | 65° | 3.5" | 0 | 9 | 0 | 70° – 79° |
| September | 79° | 58° | 4.1" | 0 | 9 | 0 | 65° – 73° |
| October | 68° | 46° | 3.7" | 0 | 8 | 0 | 53° – 63° |
| November | 56° | 36° | 3.0" | 0.3" | 9 | 0 | 40° – 52° |
| December | 47° | 30° | 3.4" | 2.8" | 10 | 2 | 29° – 49° |
| Year | 66° | 46° | 42.6" | 21.0" | 121 | 14 |
“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 Chantilly
Chantilly gets 43 inches of rain and melted snow a year. May is the wettest month and February the driest. Rain or snow falls on about 121 days a year. Snow covers the ground about 14 days of the year.
About 194 frost-free days a year
In half of years the last 32° night comes by April 15 and the first one by October 24. That leaves about 194 frost-free days for gardens, longer than 68% of U.S. towns.
Heating and cooling a home in Chantilly
Engineers use “degree days” to estimate how hard a furnace or air conditioner works. In Chantilly, 79% of that work is heating and 21% is cooling.
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.
Chantilly and its neighbors
Chantilly borders 6 towns with climate data. January nights across them vary by 0.4°. Sully Square has the coldest January nights (25°) and Bull Run the hottest July afternoons (88°). Chantilly’s January low is 26° and its July high 87°.
Temperatures and rain come from NOAA’s 5 km grid, so each town gets its own value.
How Chantilly 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 Chantilly averaged 1.7° warmer than the 1900s. The biggest change is in December (+2.9°). The shift is larger than in 81% of U.S. towns.
Change by month1991–2020 average minus 1901–2000 average, at Chantilly’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 29° to 49°. September is the most reliable, staying within 7°.
Common questions about Chantilly’s climate
What is the coldest month in Chantilly?
January, with a typical high of 43° and a low of 26°.
What is the hottest month in Chantilly?
July, with a typical high of 87° and a low of 67°. About 33 days a year reach 90°.
How much snow does Chantilly get?
About 21 inches in a normal winter, most of it in February.
When is the first frost in Chantilly?
In half of years the first 32° night comes by October 24, and the last spring frost by April 15.
What is the rainiest month in Chantilly?
May, with 4.3 inches of rain and melted snow. The year totals 43 inches.
Temperatures and rainfall come from NOAA’s gridded climate normals for Chantilly itself (about a 3-mile square). Snow, frost dates and day counts come from NOAA’s weather station at Washington Dc Dulles Airport, VA (4 mi) away. Normals are 30-year averages, not a forecast. Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000.