United States · 1991–2020

Best time to visit
Bethesda.

September leads for comfortable weather in Bethesda: typically 23°C by day, 10.9°C at night, with 80 mm of rain. Based on measured 1991–2020 NOAA station history.

Best comfortSeptember

Typical high23°C

Typical low10.9°C

Rain in September80 mm

Comfort

September

September · August · June

79climate match

Beach

July

July · August · June

69climate match

Outdoors

September

September · May · October

77climate match

The weakest month is January, scoring 5 against September’s 79 — days reach only -2°C, 26° 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

5-2° / -10.8°

Feb

50.1° / -8.9°

Mar

56.4° / -3.8°

Apr

2913.4° / 2.3°

May

5820° / 8.1°

Jun

7425.5° / 13.6°

Jul

7227.9° / 16.4°

Aug

7527° / 15.7°

Sep

7923° / 10.9°

Oct

4616° / 4.6°

Nov

107.7° / -1.3°

Dec

50.6° / -7.7°

Monthly climate evidence for Bethesda — daylight is calculated from latitude, everything else is measured, sea temperature from the nearest open water 38 km away
Month	Day	Night	Rain	Wet days	Sea	Daylight	Comfort	Coverage
January	-2°C	-10.8°C	40 mm	7.1	3.4°C	9 h 20	5	Good coverage
February	0.1°C	-8.9°C	42 mm	6.3	2.2°C	10 h 27	5	Good coverage
March	6.4°C	-3.8°C	47 mm	6	2.1°C	11 h 47	5	Good coverage
April	13.4°C	2.3°C	91 mm	8.9	3.3°C	13 h 20	29	Good coverage
May	20°C	8.1°C	104 mm	10.1	5.9°C	14 h 38	58	Good coverage
June	25.5°C	13.6°C	124 mm	9.4	12.5°C	15 h 20	74	Good coverage
July	27.9°C	16.4°C	98 mm	7.1	19.6°C	15 h 03	72	Good coverage
August	27°C	15.7°C	106 mm	7.9	21.3°C	13 h 56	75	Good coverage
September	23°C	10.9°C	80 mm	7.2	19.0°C	12 h 26	79	Good coverage
October	16°C	4.6°C	69 mm	7.7	13.4°C	10 h 58	46	Good coverage
November	7.7°C	-1.3°C	56 mm	6.9	8.2°C	9 h 40	10	Good coverage
December	0.6°C	-7.7°C	47 mm	6.6	5.2°C	9 h 01	5	Good coverage

Records at WAUKESHA WWTP, 1894–2026
Month	Record high	Record low	Wettest day	Wettest / driest month	Years
January	16.7°C26 Jan 1944	-32.8°C25 Jan 1904	68 mm24 Jan 1938	142 mm1918 · driest 2 mm in 2025	117
February	21.7°C28 Feb 2024	-33.3°C3 Feb 1996	47 mm23 Feb 1922	98 mm2013 · driest 0 mm in 1987	115
March	27.8°C22 Mar 2012	-25.6°C8 Mar 1943	56 mm16 Mar 2026	141 mm1976 · driest 5 mm in 1968	117
April	32.8°C22 Apr 1980	-13.9°C7 Apr 1982	86 mm21 Apr 1973	219 mm2026 · driest 5 mm in 1932	118
May	38.3°C31 May 1934	-3.9°C1 May 1943	89 mm13 May 2014	240 mm2004 · driest 15 mm in 2026	119
June	38.3°C1 Jun 1934	-1.7°C4 Jun 1945	103 mm22 Jun 1940	282 mm2010 · driest 14 mm in 1995	118
July	42.8°C14 Jul 1995	5.0°C31 Jul 1918	129 mm18 Jul 1952	290 mm1952 · driest 10 mm in 1916	116
August	38.9°C6 Aug 1918	1.7°C28 Aug 1915	152 mm10 Aug 2025	275 mm1995 · driest 13 mm in 2003	114
September	38.3°C2 Sep 1953	-3.9°C28 Sep 1942	94 mm13 Sep 1961	259 mm1961 · driest 0 mm in 1979	116
October	31.1°C6 Oct 1963	-13.9°C30 Oct 1925	58 mm18 Oct 1923	152 mm1917 · driest 2 mm in 1924	119
November	25.6°C1 Nov 1944	-22.8°C24 Nov 1950	62 mm1 Nov 1982	165 mm1934 · driest 5 mm in 2007	115
December	20.0°C6 Dec 2001	-33.3°C19 Dec 1945	48 mm26 Dec 1942	107 mm1971 · driest 6 mm in 1960	115

Typical days per month at WAUKESHA WWTP, 1991–2020
Month	Days 25°C+	Days 30°C+	Frost nights	Heavy rain (10 mm+)	Snow days
January	0	0	28	1	7
February	0	0	25	1	6
March	<1	0	23	1	4
April	1	<1	9	3	1
May	7	2	<1	4	0
June	17	6	0	4	0
July	25	10	0	3	0
August	23	7	0	3	0
September	12	3	<1	3	0
October	2	<1	6	2	<1
November	0	0	19	2	1
December	0	0	27	1	6

How often, not how much — every day in WAUKESHA WWTP’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	0%	21%	4%	19%	-6.6–0.8°C
February	0%	20%	4%	17%	-4.9–3.9°C
March	3%	24%	7%	24%	2.1–9.2°C
April	14%	29%	9%	36%	10.8–16.5°C
May	39%	30%	10%	35%	17.2–22.8°C
June	64%	29%	11%	34%	23.1–27.7°C
July	75%	24%	9%	23%	26.2–30.5°C
August	74%	24%	10%	24%	24.9–29.0°C
September	54%	25%	10%	25%	20.8–25.0°C
October	23%	23%	7%	24%	13.6–18.8°C
November	2%	23%	6%	21%	4.4–9.9°C
December	0%	21%	4%	19%	-3.6–3.3°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.

1895Each stripe is one year’s mean temperature against the 104-year average. Warmest: 1998. Coolest: 1917.2025

The evidence behind this page

Nearby, measured,
and named.

Place identity: GeoNames 5245639
NOAA station: USC00478937 · WAUKESHA WWTP
Station distance: 5.5 km from the place centre
Climate period: 1991–2020
Minimum month coverage: 22 usable years
Daylight: Calculated from latitude 42.99°, mid-month, sunrise to sunset including refraction. Not a station measurement.
Sea temperature: NOAA OISST v2.1 1991–2020 monthly climatology, nearest open water 38 km from the place centre. A sheltered bay can run warmer than the open sea it is measured from.
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 WAUKESHA WWTP is what differs

Waukesha→Mukwonago→Wales→Big Bend→Buena Vista→Caldwell→

Or put two places side by side: Bethesda vs Waukesha

Best time to visitBethesda.

September

July

September

The whole year,without the guesswork.

Nearby, measured,and named.

Best time to visit
Bethesda.

The whole year,
without the guesswork.

Nearby, measured,
and named.