United States · 1991–2020

Best time to visit
Helena.

July leads for comfortable weather in Helena: typically 24.7°C by day, 15.3°C at night, with 77 mm of rain. Based on measured 1991–2020 NOAA station history.

Best comfortJuly

Typical high24.7°C

Typical low15.3°C

Rain in July77 mm

Comfort

July

July · August · June

87climate match

Beach

July

July · August · June

59climate match

Outdoors

September

September · June · May

78climate match

The weakest month is January, scoring 5 against July’s 87 — days reach only -1.9°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

5-1.9° / -9°

Feb

5-1° / -9.1°

Mar

53.4° / -4.7°

Apr

129.4° / 0.6°

May

4515.9° / 6.5°

Jun

7321.4° / 12.2°

Jul

8724.7° / 15.3°

Aug

8724.3° / 15°

Sep

7021.1° / 11.1°

Oct

3614.3° / 5.3°

Nov

57.3° / -0.1°

Dec

51.2° / -5°

Monthly climate evidence for Helena — daylight is calculated from latitude, everything else is measured, sea temperature from the nearest open water 12 km away
Month	Day	Night	Rain	Wet days	Sea	Daylight	Comfort	Coverage
January	-1.9°C	-9°C	71 mm	12.2	2.5°C	9 h 15	5	Strong coverage
February	-1°C	-9.1°C	51 mm	7.6	1.2°C	10 h 24	5	Strong coverage
March	3.4°C	-4.7°C	56 mm	7.6	1.1°C	11 h 47	5	Good coverage
April	9.4°C	0.6°C	89 mm	9.4	2.4°C	13 h 22	12	Strong coverage
May	15.9°C	6.5°C	84 mm	9.7	5.3°C	14 h 42	45	Strong coverage
June	21.4°C	12.2°C	88 mm	9	12.1°C	15 h 26	73	Strong coverage
July	24.7°C	15.3°C	77 mm	7.9	18.9°C	15 h 09	87	Strong coverage
August	24.3°C	15°C	86 mm	7.8	20.9°C	13 h 59	87	Strong coverage
September	21.1°C	11.1°C	91 mm	8.7	19.0°C	12 h 27	70	Good coverage
October	14.3°C	5.3°C	87 mm	11.5	13.8°C	10 h 56	36	Good coverage
November	7.3°C	-0.1°C	79 mm	10.8	8.9°C	9 h 35	5	Strong coverage
December	1.2°C	-5°C	65 mm	11.1	5.4°C	8 h 56	5	Strong coverage

What has changed

Helena runs 0.0°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

+0.5

Feb

+0.5

Mar

+0.2

Apr

-1.4

May

-1.3

Jun

-0.8

Jul

-0.4

Aug

-0.2

Sep

+0.5

Oct

+0.5

Nov

+0.5

Dec

+1.4

July daytime highs, 2011–2025. Last recorded: 26.1°C.

Records at HARBOR BEACH 1 SSE, 1899–2026
Month	Record high	Record low	Wettest day	Wettest / driest month	Years
January	16.7°C26 Jan 1944	-28.3°C10 Jan 1982	47 mm1 Jan 1985	121 mm1985 · driest 12 mm in 1945	125
February	20.0°C23 Feb 1984	-30.0°C9 Feb 1934	48 mm7 Feb 2020	118 mm1985 · driest 8 mm in 1934	126
March	28.9°C29 Mar 1910	-24.4°C7 Mar 1986	61 mm16 Mar 1942	137 mm2016 · driest 5 mm in 1910	125
April	31.7°C24 Apr 1915	-16.1°C1 Apr 1923	127 mm12 Apr 2018	326 mm2018 · driest 7 mm in 1946	124
May	33.3°C30 May 1919	-4.4°C4 May 1912	76 mm21 May 1911	206 mm1912 · driest 14 mm in 1950	126
June	37.8°C1 Jun 1934	0.0°C4 Jun 1910	102 mm17 Jun 1935	220 mm1967 · driest 12 mm in 1938	126
July	40.6°C10 Jul 1936	3.3°C3 Jul 1907	69 mm15 Jul 1955	187 mm1902 · driest 9 mm in 2001	127
August	38.9°C13 Aug 1918	1.7°C28 Aug 1982	91 mm16 Aug 1977	232 mm1977 · driest 5 mm in 1899	126
September	36.7°C1 Sep 1953	-6.1°C29 Sep 1899	153 mm10 Sep 1986	360 mm1986 · driest 16 mm in 1917	123
October	31.1°C6 Oct 1900	-12.2°C31 Oct 2018	79 mm4 Oct 2013	171 mm1954 · driest 13 mm in 1975	125
November	26.7°C1 Nov 1950	-15.6°C16 Nov 1933	46 mm1 Nov 1982	143 mm2003 · driest 2 mm in 1904	124
December	18.3°C6 Dec 2001	-25.6°C24 Dec 1960	68 mm30 Dec 1972	203 mm1972 · driest 10 mm in 1919	125

Typical days per month at HARBOR BEACH 1 SSE, 1991–2020
Month	Days 25°C+	Days 30°C+	Frost nights	Heavy rain (10 mm+)	Snow days
January	0	0	29	2	7
February	0	0	27	2	5
March	<1	0	26	2	3
April	<1	0	14	3	<1
May	4	<1	1	3	0
June	8	2	0	3	0
July	14	4	0	3	0
August	12	2	0	3	0
September	6	<1	0	3	0
October	<1	<1	4	3	<1
November	0	0	17	2	1
December	0	0	27	1	5

How often, not how much — every day in HARBOR BEACH 1 SSE’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%	32%	5%	38%	-4.7–1.3°C
February	0%	29%	5%	32%	-4.4–1.9°C
March	2%	26%	6%	30%	0.8–7.0°C
April	8%	29%	8%	31%	7.6–13.1°C
May	23%	29%	9%	33%	14.0–19.8°C
June	48%	29%	9%	29%	20.1–24.7°C
July	71%	25%	8%	23%	23.8–27.4°C
August	71%	24%	9%	21%	23.0–26.8°C
September	46%	30%	9%	33%	19.7–23.2°C
October	15%	31%	8%	37%	12.6–17.3°C
November	2%	32%	7%	39%	5.1–10.0°C
December	0%	32%	5%	40%	-2.0–3.6°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.

1900Each stripe is one year’s mean temperature against the 109-year average. Warmest: 2024. Coolest: 2014.2025

The evidence behind this page

Nearby, measured,
and named.

Place identity: GeoNames 4995732
NOAA station: USC00203585 · HARBOR BEACH 1 SSE
Station distance: 7.5 km from the place centre
Climate period: 1991–2020
Minimum month coverage: 23 usable years
Daylight: Calculated from latitude 43.77°, mid-month, sunrise to sunset including refraction. Not a station measurement.
Sea temperature: NOAA OISST v2.1 1991–2020 monthly climatology, nearest open water 12 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 HARBOR BEACH 1 SSE is what differs

Harbor Beach→Minden City→Forestville→Charleston→Parisville→Ruth→

Or put two places side by side: Helena vs Harbor Beach

Best time to visitHelena.

July

July

September

The whole year,without the guesswork.

Helena runs 0.0°Con the 1961–1990 baseline.

Nearby, measured,and named.

Best time to visit
Helena.

The whole year,
without the guesswork.

Helena runs 0.0°C
on the 1961–1990 baseline.

Nearby, measured,
and named.