United States · 1991–2020

Best time to visit
Bethalto.

September leads for comfortable weather in Bethalto: typically 26.6°C by day, 16.1°C at night, with 85 mm of rain. Based on measured 1991–2020 NOAA station history.

Best comfortSeptember

Typical high26.6°C

Typical low16.1°C

Rain in September85 mm

Comfort

September

September · May · October

80climate match

Beach

August

August · July · June

84climate match

Outdoors

October

October · April · September

88climate match

The weakest month is January, scoring 5 against September’s 80 — days reach only 3.9°C, 20° 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

53.9° / -5.2°

Feb

56.6° / -3.3°

Mar

2612.2° / 2.1°

Apr

5418.9° / 8°

May

7623.7° / 13.8°

Jun

6328.7° / 19.3°

Jul

5530.6° / 21.2°

Aug

6229.9° / 20.2°

Sep

8026.6° / 16.1°

Oct

6819.9° / 9.7°

Nov

3012.6° / 3.2°

Dec

56.4° / -2.1°

Monthly climate evidence for Bethalto — daylight is calculated from latitude, everything else is measured
Month	Day	Night	Rain	Wet days	Daylight	Comfort	Coverage
January	3.9°C	-5.2°C	68 mm	6.1	9 h 43	5	Strong coverage
February	6.6°C	-3.3°C	66 mm	6	10 h 40	5	Strong coverage
March	12.2°C	2.1°C	85 mm	8.3	11 h 50	26	Strong coverage
April	18.9°C	8°C	119 mm	8.6	13 h 10	54	Strong coverage
May	23.7°C	13.8°C	139 mm	9.9	14 h 16	76	Strong coverage
June	28.7°C	19.3°C	105 mm	7.8	14 h 53	63	Strong coverage
July	30.6°C	21.2°C	98 mm	6.4	14 h 38	55	Strong coverage
August	29.9°C	20.2°C	81 mm	6	13 h 41	62	Strong coverage
September	26.6°C	16.1°C	85 mm	5.8	12 h 24	80	Strong coverage
October	19.9°C	9.7°C	74 mm	6.6	11 h 07	68	Good coverage
November	12.6°C	3.2°C	84 mm	7.3	10 h	30	Strong coverage
December	6.4°C	-2.1°C	68 mm	6.3	9 h 27	5	Strong coverage

What has changed

Bethalto runs +1.2°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

+2.1

Feb

+2.3

Mar

+3.0

Apr

+1.0

May

+0.1

Jun

+0.4

Jul

-0.4

Aug

-0.5

Sep

+1.2

Oct

+1.1

Nov

+0.7

Dec

+3.1

September daytime highs, 2011–2025. Last recorded: 28.4°C.

Records at ALTON - MELVIN PRICE L&D, 1943–2026
Month	Record high	Record low	Wettest day	Wettest / driest month	Years
January	25.0°C9 Jan 2008	-26.7°C11 Jan 1982	91 mm4 Jan 1950	242 mm2005 · driest 2 mm in 1986	79
February	26.7°C28 Feb 2024	-26.1°C4 Feb 1996	127 mm2 Feb 2011	155 mm2011 · driest 1 mm in 1947	81
March	31.7°C25 Mar 1946	-18.3°C5 Mar 1960	105 mm28 Mar 1977	206 mm1977 · driest 23 mm in 1956	81
April	38.9°C21 Apr 1946	-6.7°C6 Apr 1982	196 mm23 Apr 1996	446 mm1996 · driest 21 mm in 1988	81
May	36.7°C16 May 1944	0.0°C10 May 1966	119 mm17 May 1995	300 mm2004 · driest 22 mm in 2014	80
June	41.7°C27 Jun 1952	6.7°C3 Jun 1945	126 mm17 Jun 2004	273 mm1951 · driest 10 mm in 1991	81
July	46.7°C10 Jul 1946	10.0°C6 Jul 1972	119 mm16 Jul 1952	257 mm2016 · driest 1 mm in 2014	80
August	41.1°C1 Aug 1953	7.8°C29 Aug 1986	110 mm16 Aug 1946	375 mm1946 · driest 5 mm in 2024	75
September	39.4°C4 Sep 1954	2.8°C30 Sep 1949	88 mm17 Sep 1969	292 mm1993 · driest 1 mm in 2014	79
October	36.7°C29 Oct 1945	-3.9°C21 Oct 1952	89 mm4 Oct 1986	181 mm1986 · driest 0 mm in 2010	78
November	31.1°C7 Nov 1945	-15.6°C30 Nov 1964	137 mm1 Nov 1946	325 mm1946 · driest 3 mm in 2012	81
December	23.3°C5 Dec 2012	-26.7°C22 Dec 1989	141 mm27 Dec 2015	325 mm2015 · driest 4 mm in 1955	81

Typical days per month at ALTON - MELVIN PRICE L&D, 1991–2020
Month	Days 25°C+	Days 30°C+	Frost nights	Heavy rain (10 mm+)	Snow days
January	0	0	22	2	<1
February	0	0	18	2	<1
March	1	0	10	3	<1
April	5	<1	1	4	0
May	14	3	0	5	0
June	24	12	0	3	0
July	27	18	0	3	0
August	28	15	0	3	0
September	19	7	0	3	0
October	6	<1	<1	3	0
November	<1	0	7	3	<1
December	0	0	18	2	<1

The best month has moved. On the 1961–1990 numbers the strongest month here was September (scoring 86); 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 ALTON - MELVIN PRICE L&D’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%	19%	6%	16%	0.3–7.0°C
February	2%	22%	6%	21%	2.3–9.6°C
March	12%	28%	10%	33%	7.5–15.2°C
April	32%	30%	12%	38%	15.9–22.0°C
May	58%	29%	13%	34%	21.5–26.6°C
June	74%	25%	10%	26%	27.0–31.1°C
July	78%	22%	11%	21%	29.3–34.1°C
August	80%	20%	8%	18%	28.5–32.5°C
September	76%	20%	8%	17%	24.7–29.2°C
October	46%	21%	8%	23%	18.1–23.4°C
November	12%	23%	9%	22%	8.7–15.2°C
December	1%	21%	7%	21%	3.0–9.3°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.

1944Each stripe is one year’s mean temperature against the 59-year average. Warmest: 1946. Coolest: 1979.2025

The evidence behind this page

Nearby, measured,
and named.

Place identity: GeoNames 4233662
NOAA station: USC00110137 · ALTON - MELVIN PRICE L&D
Station distance: 10.5 km from the place centre
Climate period: 1991–2020
Minimum month coverage: 22 usable years
Daylight: Calculated from latitude 38.91°, 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 ALTON - MELVIN PRICE L&D is what differs

Upper Alton→Alton→Edwardsville→Spanish Lake→Godfrey→Glen Carbon→

Or put two places side by side: Bethalto vs Upper Alton

Best time to visitBethalto.