United States · 1991–2020

Best time to visit
Somerset.

September leads for comfortable weather in Somerset: typically 27.1°C by day, 15.2°C at night, with 116 mm of rain. Based on measured 1991–2020 NOAA station history.

Best comfortSeptember

Typical high27.1°C

Typical low15.2°C

Rain in September116 mm

Comfort

September

September · May · June

74climate match

Beach

August

August · June · July

70climate match

Outdoors

April

April · October · May

76climate match

The weakest month is January, scoring 5 against September’s 74 — days reach only 6.9°C, 17° 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

56.9° / -3.7°

Feb

88.8° / -2.7°

Mar

2513.5° / 0.9°

Apr

6020.5° / 6.4°

May

7325° / 11.9°

Jun

6229.7° / 17.1°

Jul

4632.1° / 19.8°

Aug

5530.9° / 19°

Sep

7427.1° / 15.2°

Oct

6220.8° / 8.2°

Nov

3514.4° / 2.5°

Dec

79.1° / -1.4°

Monthly climate evidence for Somerset — daylight is calculated from latitude, everything else is measured
Month	Day	Night	Rain	Wet days	Daylight	Comfort	Coverage
January	6.9°C	-3.7°C	80 mm	7.8	9 h 43	5	Strong coverage
February	8.8°C	-2.7°C	79 mm	7.7	10 h 40	8	Strong coverage
March	13.5°C	0.9°C	106 mm	8.8	11 h 50	25	Strong coverage
April	20.5°C	6.4°C	91 mm	9	13 h 10	60	Strong coverage
May	25°C	11.9°C	117 mm	9.9	14 h 17	73	Strong coverage
June	29.7°C	17.1°C	110 mm	8.8	14 h 53	62	Strong coverage
July	32.1°C	19.8°C	132 mm	8.7	14 h 39	46	Strong coverage
August	30.9°C	19°C	108 mm	8.2	13 h 41	55	Strong coverage
September	27.1°C	15.2°C	116 mm	7.6	12 h 24	74	Strong coverage
October	20.8°C	8.2°C	109 mm	7.6	11 h 07	62	Strong coverage
November	14.4°C	2.5°C	85 mm	7.2	9 h 59	35	Strong coverage
December	9.1°C	-1.4°C	100 mm	8.6	9 h 27	7	Strong coverage

What has changed

Somerset runs -0.2°C
on the 1961–1990 baseline.

Each bar compares the 2011–2025 daytime average for that month against the same month in 1961–1990, measured at the same station. Months where the older record is too thin to compare are left blank.

Jan

+0.3

Feb

+0.2

Mar

-1.3

Apr

0.0

May

-1.0

Jun

-0.3

Jul

+0.6

Aug

-0.3

Sep

-0.3

Oct

-0.3

Nov

-1.2

Dec

+1.2

September daytime highs, 2011–2024. Last recorded: 26.3°C.

Records at DALECARLIA RSVR, 1948–2026
Month	Record high	Record low	Wettest day	Wettest / driest month	Years
January	26.1°C27 Jan 1950	-23.9°C21 Jan 1985	89 mm8 Jan 1999	199 mm2024 · driest 7 mm in 1955	78
February	27.8°C22 Feb 2018	-18.3°C18 Feb 1979	74 mm22 Feb 2003	216 mm2003 · driest 0 mm in 2002	77
March	32.8°C30 Mar 1998	-15.0°C11 Mar 1960	132 mm9 Mar 1999	235 mm1999 · driest 4 mm in 2006	77
April	35.0°C28 Apr 2009	-8.3°C9 Apr 2000	80 mm14 Apr 1970	237 mm1952 · driest 9 mm in 1985	74
May	36.7°C29 May 1999	-5.0°C8 May 1992	80 mm6 May 1989	239 mm1989 · driest 19 mm in 2007	75
June	37.8°C22 Jun 1988	-1.1°C23 Jun 1992	150 mm22 Jun 1972	362 mm2006 · driest 22 mm in 1966	74
July	39.4°C31 Jul 1954	5.6°C7 Jul 1996	128 mm25 Jul 1991	249 mm2018 · driest 21 mm in 1999	74
August	40.6°C17 Aug 1997	5.0°C29 Aug 1986	136 mm11 Aug 2001	351 mm1955 · driest 5 mm in 2025	78
September	37.2°C24 Sep 1984	-0.6°C21 Sep 1956	140 mm14 Sep 1966	299 mm2018 · driest 7 mm in 2019	77
October	35.0°C10 Oct 2007	-8.9°C22 Oct 1992	147 mm8 Oct 2005	280 mm2005 · driest 2 mm in 1963	77
November	30.6°C1 Nov 1971	-13.3°C15 Nov 1992	113 mm28 Nov 1993	230 mm2018 · driest 10 mm in 2016	73
December	27.8°C6 Dec 1998	-18.9°C22 Dec 1989	110 mm24 Dec 1994	176 mm1969 · driest 0 mm in 2021	76

Typical days per month at DALECARLIA RSVR, 1991–2020
Month	Days 25°C+	Days 30°C+	Frost nights	Heavy rain (10 mm+)	Snow days
January	0	0	24	3	1
February	<1	0	20	3	1
March	2	<1	14	3	<1
April	8	2	3	3	0
May	16	7	<1	4	0
June	26	16	0	3	0
July	30	24	0	4	0
August	29	20	0	3	0
September	21	9	0	4	0
October	7	<1	2	3	0
November	<1	0	10	3	0
December	<1	0	20	3	<1

The best month has moved. On the 1961–1990 numbers the strongest month here was September (scoring 82); on 2011–2025 it is May (85). Both are scored the same way, from the same station — only the climate underneath changed.

How often, not how much — every day in DALECARLIA RSVR’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%	26%	9%	30%	3.5–10.2°C
February	4%	27%	10%	31%	5.5–12.4°C
March	14%	28%	10%	34%	10.4–16.4°C
April	39%	28%	10%	35%	18.1–22.4°C
May	62%	31%	12%	37%	22.7–27.3°C
June	73%	27%	10%	29%	27.8–31.2°C
July	73%	27%	12%	29%	30.0–33.3°C
August	75%	25%	11%	25%	29.3–32.5°C
September	74%	23%	10%	22%	25.3–28.6°C
October	49%	22%	10%	20%	19.0–22.8°C
November	14%	24%	9%	21%	11.8–16.9°C
December	3%	26%	10%	30%	5.4–12.0°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.

1949Each stripe is one year’s mean temperature against the 63-year average. Warmest: 1998. Coolest: 1992.2023

The evidence behind this page

Nearby, measured,
and named.

Place identity: GeoNames 4369891
NOAA station: USC00182325 · DALECARLIA RSVR
Station distance: 3.4 km from the place centre
Climate period: 1991–2020
Minimum month coverage: 27 usable years
Daylight: Calculated from latitude 38.97°, 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 DALECARLIA RSVR is what differs

Arlington→Bethesda→McLean→Mount Pleasant→Foggy Bottom→Falls Church→

Or put two places side by side: Somerset vs Arlington

Best time to visitSomerset.

September

August

April

The whole year,without the guesswork.

Somerset runs -0.2°Con the 1961–1990 baseline.

Nearby, measured,and named.

Best time to visit
Somerset.

The whole year,
without the guesswork.

Somerset runs -0.2°C
on the 1961–1990 baseline.

Nearby, measured,
and named.