Rockville, Maryland climate: Normal weather by month, frost dates and records
Rockville's normal year runs from 27°F January nights to 87°F July afternoons, with 41.3 inches of precipitation a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 13.4°C, January lows of −3°C, July highs of 31°C, 1,050 mm of precipitation a year.
- NOAA stationRockville (1 mi NE)
- Station IDUSC00187705
- Location39.10°N 77.15°W
- Elevation440 ft (134 m)
- From the center1 miles
- Population68,417
On October 23, the normal high in Rockville is 64°F and the normal low 45°F, and the chance of measurable rain or snow is 26%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Rockville.
- Jan 42° 27°
- Feb 45° 28°
- Mar 54° 36°
- Apr 66° 46°
- May 74° 55°
- Jun 82° 64°
- Jul 87° 69°
- Aug 85° 67°
- Sep 78° 60°
- Oct 66° 48°
- Nov 56° 38°
- Dec 46° 31°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
What is the weather like in Rockville each month?
July is the warmest month, with normal highs of 87°F; January the coldest, with normal lows of 27°F. The most precipitation falls in September (4.01 in), the least in February (2.60 in).
Each month has its own page with the day-by-day normals, the month's records and its recent years:
| Month | High | Low | Mean | Precip. | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|
| January | 42°F | 27°F | 34.5°F | 3.11 | 10 | <1 | 22 | 9 h 40 min |
| February | 45°F | 28°F | 36.7°F | 2.60 | 8 | <1 | 20 | 10 h 40 min |
| March | 54°F | 36°F | 44.8°F | 3.66 | 11 | <1 | 13 | 11 h 50 min |
| April | 66°F | 46°F | 55.7°F | 3.23 | 10 | <1 | 2 | 13 h 10 min |
| May | 74°F | 55°F | 64.6°F | 3.55 | 11 | 2 | <1 | 14 h 20 min |
| June | 82°F | 64°F | 72.9°F | 3.96 | 10 | 4 | <1 | 14 h 50 min |
| July | 87°F | 69°F | 78.0°F | 3.98 | 10 | 10 | <1 | 14 h 40 min |
| August | 85°F | 67°F | 75.9°F | 3.05 | 7 | 6 | <1 | 13 h 40 min |
| September | 78°F | 60°F | 68.7°F | 4.01 | 10 | 1 | <1 | 12 h 30 min |
| October | 66°F | 48°F | 57.0°F | 3.52 | 8 | <1 | <1 | 11 h 10 min |
| November | 56°F | 38°F | 46.9°F | 3.27 | 8 | <1 | 9 | 10 h |
| December | 46°F | 31°F | 38.5°F | 3.38 | 9 | <1 | 20 | 9 h 30 min |
| Year (annual) | 65°F | 47°F | 56.2°F | 41.32 | 113 | 23 | 86 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. |
|---|---|---|---|---|
| January | 6°C | −3°C | 1.4°C | 79 mm |
| February | 7°C | −2°C | 2.6°C | 66 mm |
| March | 12°C | 2°C | 7.1°C | 93 mm |
| April | 19°C | 8°C | 13.2°C | 82 mm |
| May | 24°C | 13°C | 18.1°C | 90 mm |
| June | 28°C | 18°C | 22.7°C | 101 mm |
| July | 31°C | 20°C | 25.6°C | 101 mm |
| August | 29°C | 19°C | 24.4°C | 77 mm |
| September | 25°C | 16°C | 20.4°C | 102 mm |
| October | 19°C | 9°C | 13.9°C | 89 mm |
| November | 13°C | 3°C | 8.3°C | 83 mm |
| December | 8°C | −1°C | 3.6°C | 86 mm |
NOAA publishes no 1991-2020 snowfall normal for this station. The nearest record that keeps one, Dalecarlia Reservoir (11 miles away), gets 6 inches of snow in a normal year; elevation and distance can change that.
Source: NOAA NCEI 1991-2020 monthly normals, station USC00187705; annual normals. Wet days: 0.01 inch or more; 90°F days and freezing nights: NOAA's day counts. Daylight: sunrise to sunset on the 15th, computed from the latitude.
When is the best weather to visit Rockville?
Normal highs sit between 65°F and 85°F in April, May, June, August, September and October. Of those, August has the fewest days with rain (7).
That is a measurement, not a recommendation: it counts the months whose normal afternoon high sits between 65°F and 85°F, where a light layer is enough by day.
Source: NOAA NCEI 1991-2020 monthly normals, station USC00187705.
When is the last frost in Rockville?
In Rockville, the last spring frost (32°F) comes after April 1 in half of years and after April 15 in one year in ten; the first autumn frost comes before November 6 in half of years and before October 24 in one year in ten.
Frost-free in half of yearsFrost in 1 to 9 years out of 10Frost most years
- Last spring frost, half of years after
- April 11 year in 10 after April 15; 9 in 10 after March 19
- First autumn frost, half of years before
- November 61 year in 10 before October 24; 9 in 10 before November 21
NOAA puts the median frost-free season at 219 days, and the season without a hard freeze (28°F) at 243 days.
A hard freeze (28°F) comes after March 22 in half of springs and before November 19 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Rockville in zone 7b across its 3 ZIP code areas (7b in 20850, the largest). By the map's own method, the average of each year's coldest night over 1991-2020, Rockville's NOAA station is in zone 7b: the coldest night of a typical year reaches 7°F (15 complete years).
Frost dates for every NOAA station in Maryland · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USC00187705; USDA 2023 Plant Hardiness Zone Map, ZIP listings: PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed October 8, 2026; the station zone: ACIS daily lows, 1991-2020. A 10% date means one year in ten has a frost after it in spring or before it in autumn.
What hardiness zone is each Rockville ZIP code in?
The USDA's 2023 map gives each ZIP code area one zone. Rockville's 3 ZIP code areas are all in zone 7b. Each ZIP's frost dates are in the frost tool.
Source: USDA 2023 Plant Hardiness Zone Map, ZIP listings: PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed October 8, 2026; ZIP areas in the place: Census Bureau 2020 ZCTA-to-place relationship file. A ZIP area counts when at least a tenth of its land (and 0.5 km²) lies in the place.
How hot and how cold does it get in Rockville?
In a normal year in Rockville, 23 days a year reach 90°F, 86 nights fall to 32°F or colder and 113 days bring measurable precipitation.
- Days at 90°F or more
- 23a normal year
- Days at 100°F or more
- fewer than 1a normal year
- Nights at 32°F or colder
- 86a normal year
- Days that stay below freezing
- 14high of 32°F or less
- Days with 0.01 inch of precipitation
- 113a normal year
The highest temperature in this station's record (since 1907) is 104°F, on August 7, 1918; the lowest is −13°F, on January 21, 1985.
The wettest calendar year on that record is 1972, with 64.23 in; the snowiest season is 1960–61, with 52.9 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USC00187705; records: ACIS (NOAA Regional Climate Centers), station USC00187705. Records use complete months only; a month missing more than three days is left out.
How sunny is Rockville?
Over a year 73% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Rockville, 4.0 kWh per square metre a day. July is the sunniest month (79%) and January the cloudiest (65%). Among the 459 U.S. places of 50,000 or more, that ranks tied 352nd (with 32 others) in sunshine.
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 65% | 2.0 |
| February | 68% | 2.8 |
| March | 68% | 3.8 |
| April | 71% | 4.9 |
| May | 71% | 5.4 |
| June | 77% | 6.1 |
| July | 79% | 6.0 |
| August | 78% | 5.3 |
| September | 75% | 4.3 |
| October | 72% | 3.1 |
| November | 72% | 2.3 |
| December | 66% | 1.7 |
Source: NASA POWER solar climatology, 2001-2020 (CERES SYN1deg). Satellite-based, for the 1-degree cell (about 100 km across) around the station, so it describes the area rather than the airport.
How much heating and cooling does Rockville need?
A normal year in Rockville brings 4,455 heating degree days, 17% fewer than the median U.S. place (5,373), and 1,279 cooling degree days, 41% more than the median (908). Five months need 300 or more heating degree days, a monthly mean of about 55°F or colder. For gardens and crops, NOAA counts 3,981 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 944 | 0 |
| February | 792 | 0 |
| March | 629 | 3 |
| April | 300 | 22 |
| May | 105 | 92 |
| June | 13 | 250 |
| July | 0 | 401 |
| August | 1 | 340 |
| September | 40 | 152 |
| October | 267 | 17 |
| November | 543 | 2 |
| December | 823 | 0 |
| Year (annual) | 4,455 | 1,279 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00187705. A degree day is one degree of a day's mean temperature below 65°F (heating) or above it (cooling); utilities use them to estimate energy use.
How does Rockville's climate compare?
Rockville is warmer than 15 of the other 25 places with their own NOAA record in Maryland, and wetter than 2. Across the 7,247 U.S. stations with normals, its annual mean of 56.2°F is warmer than 64%.
In the Köppen classification computed from these normals, Rockville is Cfa: temperate, no dry season, hot summer. What the classes mean.
Places with the most similar year elsewhere
Measured month by month on the normal high, low and precipitation, among places of 20,000 or more people in other states:
Source: NOAA NCEI 1991-2020 normals for every station PlainClimate covers. Similarity: the root-mean-square difference of the 36 monthly figures, precipitation weighted so an inch counts like 6°F.
Which places near Rockville share this climate record?
18 places have no NOAA station with 1991-2020 normals of their own, and this station is the nearest full record. A place's own climate can differ from these figures, by several degrees where it sits much higher or lower than the station, nearer the coast, or inside a large city's heat; for the larger places the next nearest records are named with their yearly mean, so the spread around them is visible, and places of 50,000 or more have their own page with NOAA's gridded normals.
- Gaithersburg, MDalso near: Damascus (8 mi, 54.0°F a year); Dalecarlia Reservoir (15 mi, 56.2°F a year)70,686 people · 4 mi NW
- Aspen Hill, MDalso near: Beltsville (9 mi, 55.9°F a year); Laurel (10 mi, 57.1°F a year)53,752 people · 4 mi E
- Olney, MD36,000 people · 5 mi NE
- North Potomac, MD23,994 people · 5 mi W
- Redland, MD18,976 people · 2 mi N
- Glenmont, MD16,529 people · 6 mi E
- Great Falls, VA14,854 people · 10 mi SW
- Flower Hill, MD13,743 people · 5 mi N
- Sugarland Run, VA12,920 people · 13 mi W
- Cascades, VA12,489 people · 13 mi W
- Dranesville, VA11,860 people · 14 mi SW
- Lowes Island, VA11,199 people · 12 mi W
- Countryside, VA9,521 people · 15 mi W
- Leisure World, MD8,693 people · 4 mi E
- Layhill, MD5,392 people · 6 mi E
- Derwood, MD1,830 people · 1 mi N
- Washington Grove, MD512 people · 3 mi NW
- Brookeville, MD168 people · 7 mi NE
Source: Census Bureau 2024 Gazetteer (place centers) and Vintage 2024 population estimates. Distance and direction from the station to each place's center.
Questions about Rockville's climate
What is the coldest month in Rockville?
January, with a normal high of 42°F and a normal low of 27°F. The warmest is July (87°F by day, 69°F at night).
Does it snow in Rockville?
Yes. NOAA publishes no 1991-2020 snowfall normal for Rockville's NOAA station; the nearest record that keeps one, Dalecarlia Reservoir (11 miles away), records 6 inches of snow in a normal year.
What is the rainiest month in Rockville?
September, with 4.01 in of precipitation in a normal year; the driest is February with 2.60 in.
What plant hardiness zone is Rockville in?
The USDA's 2023 map puts Rockville in zone 7b across its 3 ZIP code areas (7b in 20850, the largest). By the same method at Rockville's NOAA station, the coldest night of a typical year reaches 7°F (15 years, 1991-2020): zone 7b.
How late can frost come in Rockville?
In half of years the last 32°F night comes after April 1; in one year in ten it comes after April 15. Waiting until April 15 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Rockville in OctoberThis month day by day, its records and recent years
- Maryland climateThe statewide normals and every place in the state
- Dalecarlia Reservoir, MD11 miles from this station, 56.2°F a year
- Damascus, MD12 miles from this station, 54.0°F a year
- Beltsville, MD12 miles from this station, 55.9°F a year
- Laurel, MD14 miles from this station, 57.1°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made