United States · 1991–2020

Best time to visit
Rossmoor.

September leads for comfortable weather in Rossmoor: typically 24.7°C by day, 14.8°C at night, with 108 mm of rain. Based on measured 1991–2020 NOAA station history.

Best comfortSeptember

Typical high24.7°C

Typical low14.8°C

Rain in September108 mm

Comfort

September

September · May · June

83climate match

Beach

August

August · July · June

84climate match

Outdoors

October

October · April · May

81climate match

The weakest month is January, scoring 5 against September’s 83 — days reach only 5.7°C, 18° below the 24°C the score treats as ideal.

Month by month

The whole year,
without the guesswork.

The bars show the comfort score. Day and night temperatures come from daily observed highs and lows; rain is the historical monthly estimate.

Jan

55.7° / -2.9°

Feb

67.1° / -2.3°

Mar

2111.9° / 1.3°

Apr

5718.5° / 6.9°

May

7923.2° / 11.9°

Jun

7127.6° / 16.9°

Jul

5930.1° / 19.8°

Aug

6729.2° / 19.1°

Sep

8324.7° / 14.8°

Oct

6118.6° / 7.9°

Nov

3213.2° / 3.2°

Dec

77.6° / -1.2°

Monthly climate evidence for Rossmoor — daylight is calculated from latitude, everything else is measured
Month	Day	Night	Rain	Wet days	Daylight	Comfort	Coverage
January	5.7°C	-2.9°C	82 mm	8	9 h 42	5	Good coverage
February	7.1°C	-2.3°C	61 mm	6.5	10 h 40	6	Good coverage
March	11.9°C	1.3°C	102 mm	8.9	11 h 50	21	Good coverage
April	18.5°C	6.9°C	78 mm	8	13 h 10	57	Good coverage
May	23.2°C	11.9°C	88 mm	8.8	14 h 17	79	Good coverage
June	27.6°C	16.9°C	97 mm	7.8	14 h 54	71	Good coverage
July	30.1°C	19.8°C	89 mm	8.4	14 h 40	59	Good coverage
August	29.2°C	19.1°C	74 mm	5.9	13 h 42	67	Good coverage
September	24.7°C	14.8°C	108 mm	7.7	12 h 24	83	Good coverage
October	18.6°C	7.9°C	78 mm	5.9	11 h 06	61	Good coverage
November	13.2°C	3.2°C	91 mm	6.4	9 h 59	32	Good coverage
December	7.6°C	-1.2°C	76 mm	7.7	9 h 26	7	Good coverage

Records at ROCKVILLE 1 NE, 1907–2007
Month	Record high	Record low	Wettest day	Wettest / driest month	Years
January	25.6°C26 Jan 1950	-25.0°C21 Jan 1985	62 mm1 Jan 1976	208 mm1979 · driest 6 mm in 1981	68
February	27.8°C24 Feb 1985	-24.4°C10 Feb 1979	49 mm12 Feb 1985	160 mm1972 · driest 1 mm in 1966	68
March	31.7°C30 Mar 1986	-17.2°C21 Mar 1914	90 mm21 Mar 1918	204 mm1993 · driest 2 mm in 2006	70
April	37.8°C27 Apr 1915	-7.8°C1 Apr 1969	77 mm12 Apr 1913	194 mm1973 · driest 9 mm in 1985	70
May	36.1°C26 May 1914	-2.2°C9 May 1976	98 mm7 May 1912	227 mm1989 · driest 0 mm in 1964	69
June	38.9°C24 Jun 1914	1.7°C8 Jun 1977	201 mm22 Jun 1972	374 mm1972 · driest 17 mm in 1984	68
July	40.6°C31 Jul 1954	3.3°C6 Jul 1979	127 mm27 Jul 1908	249 mm1975 · driest 9 mm in 1997	69
August	40.0°C7 Aug 1918	3.9°C17 Aug 1979	114 mm1 Aug 1978	264 mm1955 · driest 5 mm in 1962	68
September	37.2°C6 Sep 1954	-2.2°C24 Sep 1974	113 mm26 Sep 1975	289 mm1979 · driest 3 mm in 1969	66
October	33.9°C4 Oct 1919	-6.7°C28 Oct 1976	111 mm23 Oct 1990	214 mm2005 · driest 0 mm in 1963	67
November	29.4°C1 Nov 1950	-12.2°C25 Nov 1970	89 mm27 Nov 1993	198 mm1963 · driest 0 mm in 1981	70
December	26.7°C29 Dec 1984	-24.4°C27 Dec 1914	58 mm24 Dec 1986	163 mm1972 · driest 8 mm in 1955	70

Typical days per month at ROCKVILLE 1 NE, 1991–2020
Month	Days 25°C+	Days 30°C+	Frost nights	Heavy rain (10 mm+)	Snow days
January	0	0	22	3	3
February	<1	0	20	2	2
March	<1	<1	13	3	1
April	5	<1	2	3	0
May	11	4	<1	3	0
June	23	10	0	3	0
July	28	17	0	3	0
August	28	14	0	2	0
September	16	3	0	4	0
October	4	0	<1	3	0
November	<1	0	9	3	<1
December	<1	0	20	3	1

How often, not how much — every day in ROCKVILLE 1 NE’s record sorted by what it was actually like, rather than averaged
Month	Warm & dry days	Wet days	Washouts	Week with 3+ wet days	Daytime mean has ranged
January	2%	25%	9%	26%	1.9–9.7°C
February	2%	25%	9%	27%	3.9–10.7°C
March	12%	27%	9%	32%	9.4–15.6°C
April	35%	27%	10%	30%	16.9–22.1°C
May	60%	29%	11%	33%	21.1–27.1°C
June	72%	27%	10%	29%	26.2–29.9°C
July	75%	25%	10%	26%	28.4–32.0°C
August	76%	24%	10%	22%	27.4–31.1°C
September	74%	21%	9%	18%	23.5–28.0°C
October	44%	19%	8%	17%	17.5–22.3°C
November	13%	21%	8%	17%	11.4–16.1°C
December	2%	23%	9%	23%	4.2–10.5°C

A warm and dry day reaches 20°C with under 1 mm of rain; a wet day gets 1 mm or more; a washout gets 10 mm or more. The week column is the share of seven-day stretches in that month, across the station’s whole daily record, that contained three or more wet days — the odds a week-long trip is rained on repeatedly, counted rather than modelled. The last column is the 10th to 90th percentile of that month’s daytime average across individual years: a narrow band means the average is what you will get, a wide one means the average is a midpoint between years that felt quite different.

1908Each stripe is one year’s mean temperature against the 57-year average. Warmest: 1998. Coolest: 1917.2006

The evidence behind this page

Nearby, measured,
and named.

Place identity: GeoNames 4367417
NOAA station: USC00187705 · ROCKVILLE 1 NE
Station distance: 6.7 km from the place centre
Climate period: 1991–2020
Minimum month coverage: 15 usable years
Daylight: Calculated from latitude 39.10°, mid-month, sunrise to sunset including refraction. Not a station measurement.
Important limit: Historical climate is not a forecast. Nearby stations can miss mountains, coasts, and local microclimates.

These places read the same station, so their numbers are identical — distance from ROCKVILLE 1 NE is what differs

Gaithersburg→Rockville→Aspen Hill→Wheaton→Potomac→North Bethesda→

Or put two places side by side: Rossmoor vs Gaithersburg

Best time to visitRossmoor.