United States · 1991–2020

Best time to visit
Boulder.

September leads for comfortable weather in Boulder: typically 25.5°C by day, 11.2°C at night, with 93 mm of rain. Based on measured 1991–2020 NOAA station history.

Best comfortSeptember

Typical high25.5°C

Typical low11.2°C

Rain in September93 mm

Comfort

September

September · August · June

75climate match

Beach

August

August · July · June

64climate match

Outdoors

October

October · September · April

70climate match

The weakest month is January, scoring 5 against September’s 75 — days reach only 4.5°C, 19° below the 24°C the score treats as ideal, and nights drop to -6.5°C.

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

54.5° / -6.5°

Feb

56.4° / -5.5°

Mar

1011.4° / -2°

Apr

4318.5° / 2.9°

May

6323° / 8.8°

Jun

6826.8° / 13.7°

Jul

6028.7° / 16.2°

Aug

7028.4° / 15.2°

Sep

7525.5° / 11.2°

Oct

5019° / 4.5°

Nov

2112.2° / -0.9°

Dec

56.8° / -3.8°

Monthly climate evidence for Boulder — daylight is calculated from latitude, everything else is measured
Month	Day	Night	Rain	Wet days	Daylight	Comfort	Coverage
January	4.5°C	-6.5°C	92 mm	12.6	9 h 42	5	Strong coverage
February	6.4°C	-5.5°C	82 mm	10.8	10 h 40	5	Strong coverage
March	11.4°C	-2°C	105 mm	11.5	11 h 50	10	Strong coverage
April	18.5°C	2.9°C	103 mm	11.5	13 h 10	43	Strong coverage
May	23°C	8.8°C	133 mm	13	14 h 17	63	Strong coverage
June	26.8°C	13.7°C	128 mm	11.4	14 h 54	68	Strong coverage
July	28.7°C	16.2°C	139 mm	11.1	14 h 39	60	Strong coverage
August	28.4°C	15.2°C	101 mm	9.6	13 h 41	70	Strong coverage
September	25.5°C	11.2°C	93 mm	8.4	12 h 24	75	Strong coverage
October	19°C	4.5°C	97 mm	9.2	11 h 06	50	Strong coverage
November	12.2°C	-0.9°C	78 mm	9	9 h 59	21	Strong coverage
December	6.8°C	-3.8°C	101 mm	11.7	9 h 26	5	Strong coverage

What has changed

Boulder runs +0.6°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

+0.1

Feb

+1.3

Mar

0.0

Apr

+0.5

May

+0.3

Jun

+0.2

Jul

+1.1

Aug

+1.0

Sep

+1.4

Oct

+0.3

Nov

-0.5

Dec

+1.2

September daytime highs, 2011–2025. Last recorded: 26.9°C.

Records at BUCKHANNON, 1891–2026
Month	Record high	Record low	Wettest day	Wettest / driest month	Years
January	26.1°C29 Jan 1914	-34.4°C19 Jan 1994	53 mm26 Jan 1902	225 mm1937 · driest 31 mm in 1967	129
February	26.7°C25 Feb 2017	-35.0°C10 Feb 1899	87 mm9 Feb 1994	182 mm2018 · driest 17 mm in 2009	130
March	30.0°C25 Mar 1916	-25.0°C3 Mar 1980	69 mm6 Mar 1967	235 mm1967 · driest 12 mm in 1910	131
April	33.9°C28 Apr 2009	-15.0°C6 Apr 1898	76 mm16 Apr 2018	196 mm2011 · driest 27 mm in 1971	132
May	35.0°C15 May 1908	-7.2°C11 May 1988	61 mm20 May 1940	327 mm1996 · driest 25 mm in 1939	131
June	35.6°C4 Jun 1895	-1.7°C8 Jun 1977	116 mm25 Jun 1950	264 mm1923 · driest 34 mm in 1967	127
July	37.2°C9 Jul 1897	1.7°C9 Jul 1913	149 mm22 Jul 2026	289 mm2026 · driest 32 mm in 1911	127
August	37.2°C7 Aug 1918	1.1°C29 Aug 1965	91 mm2 Aug 2021	241 mm1935 · driest 5 mm in 1939	125
September	37.8°C3 Sep 1953	-3.3°C29 Sep 1951	81 mm25 Sep 1940	237 mm2018 · driest 8 mm in 2019	124
October	33.3°C4 Oct 2019	-11.7°C21 Oct 1952	91 mm2 Oct 1929	234 mm1954 · driest 9 mm in 1964	128
November	27.8°C5 Nov 1948	-18.9°C29 Nov 1930	83 mm4 Nov 1985	294 mm1985 · driest 8 mm in 1904	126
December	26.1°C7 Dec 1951	-33.3°C30 Dec 1917	64 mm14 Dec 1901	208 mm1978 · driest 26 mm in 1965	129

Typical days per month at BUCKHANNON, 1991–2020
Month	Days 25°C+	Days 30°C+	Frost nights	Heavy rain (10 mm+)	Snow days
January	0	0	25	3	8
February	<1	0	24	3	6
March	1	0	21	4	4
April	6	<1	10	3	<1
May	13	3	1	5	0
June	22	7	0	5	0
July	28	12	0	5	0
August	27	10	0	3	0
September	18	6	0	3	0
October	6	<1	7	3	<1
November	<1	0	19	3	2
December	0	0	24	4	5

How often, not how much — every day in BUCKHANNON’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	<1%	42%	11%	61%	1.4–8.9°C
February	2%	40%	11%	57%	2.5–10.0°C
March	11%	40%	13%	56%	8.0–15.7°C
April	30%	38%	12%	52%	15.7–20.7°C
May	50%	38%	14%	52%	20.9–25.7°C
June	62%	36%	16%	48%	25.1–28.8°C
July	64%	36%	15%	46%	26.9–30.4°C
August	69%	31%	13%	36%	26.2–30.0°C
September	66%	27%	11%	30%	23.1–27.4°C
October	39%	28%	10%	34%	16.9–21.7°C
November	11%	33%	10%	42%	9.3–15.5°C
December	1%	38%	12%	51%	3.5–10.4°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.

1892Each stripe is one year’s mean temperature against the 114-year average. Warmest: 1921. Coolest: 1963.2025

The evidence behind this page

Nearby, measured,
and named.

Place identity: GeoNames 4799863
NOAA station: USC00461220 · BUCKHANNON
Station distance: 14.1 km from the place centre
Climate period: 1991–2020
Minimum month coverage: 30 usable years
Daylight: Calculated from latitude 39.07°, 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 BUCKHANNON is what differs

Buckhannon→Century→Aberdeen→Atlas→Century Junction→Daysville→

Or put two places side by side: Boulder vs Buckhannon

Best time to visitBoulder.