United States · 1991–2020

Best time to visit
Cahokia.

September leads for comfortable weather in Cahokia: typically 26.4°C by day, 14.3°C at night, with 88 mm of rain. Based on measured 1991–2020 NOAA station history.

Best comfortSeptember

Typical high26.4°C

Typical low14.3°C

Rain in September88 mm

Comfort

September

September · May · October

80climate match

Beach

August

August · June · July

79climate match

Outdoors

October

October · April · September

81climate match

The weakest month is January, scoring 5 against September’s 80 — days reach only 4.8°C, 19° 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

54.8° / -5.2°

Feb

108.3° / -2.8°

Mar

3013.7° / 1.9°

Apr

5719.9° / 7.6°

May

7724.6° / 13.3°

Jun

6229.1° / 18.3°

Jul

5031.2° / 20.5°

Aug

6130.7° / 19.4°

Sep

8026.4° / 14.3°

Oct

6820.9° / 7.8°

Nov

3113.6° / 2.4°

Dec

56.6° / -3.1°

Monthly climate evidence for Cahokia — daylight is calculated from latitude, everything else is measured
Month	Day	Night	Rain	Wet days	Daylight	Comfort	Coverage
January	4.8°C	-5.2°C	71 mm	7.4	9 h 45	5	Good coverage
February	8.3°C	-2.8°C	59 mm	6.4	10 h 42	10	Good coverage
March	13.7°C	1.9°C	87 mm	8.4	11 h 50	30	Good coverage
April	19.9°C	7.6°C	105 mm	9.6	13 h 09	57	Good coverage
May	24.6°C	13.3°C	119 mm	10.1	14 h 15	77	Good coverage
June	29.1°C	18.3°C	107 mm	8.6	14 h 51	62	Good coverage
July	31.2°C	20.5°C	122 mm	7.3	14 h 37	50	Good coverage
August	30.7°C	19.4°C	80 mm	6.5	13 h 40	61	Good coverage
September	26.4°C	14.3°C	88 mm	6.3	12 h 23	80	Good coverage
October	20.9°C	7.8°C	78 mm	6.8	11 h 07	68	Good coverage
November	13.6°C	2.4°C	92 mm	7.4	10 h 01	31	Good coverage
December	6.6°C	-3.1°C	63 mm	6.8	9 h 29	5	Good coverage

Records at CAHOKIA, 1969–2012
Month	Record high	Record low	Wettest day	Wettest / driest month	Years
January	25.6°C21 Jan 1986	-28.3°C17 Jan 1977	61 mm3 Jan 2005	210 mm2005 · driest 0 mm in 1981	40
February	27.2°C25 Feb 2000	-25.0°C3 Feb 1996	63 mm7 Feb 1999	187 mm1986 · driest 2 mm in 1983	38
March	31.7°C28 Mar 1985	-21.7°C5 Mar 1978	79 mm28 Mar 1977	202 mm2008 · driest 33 mm in 2001	41
April	33.9°C15 Apr 2006	-7.8°C6 Apr 1990	76 mm28 Apr 1994	285 mm1994 · driest 23 mm in 1971	40
May	34.4°C20 May 1987	0.0°C6 May 1989	111 mm16 May 1990	344 mm1995 · driest 30 mm in 1992	39
June	39.4°C30 Jun 1978	5.0°C9 Jun 1988	68 mm12 Jun 2002	211 mm1998 · driest 12 mm in 1984	37
July	41.1°C16 Jul 1980	6.7°C6 Jul 1972	88 mm10 Jul 1991	282 mm1987 · driest 4 mm in 1984	40
August	40.6°C16 Aug 2007	5.0°C28 Aug 1986	109 mm18 Aug 1998	169 mm1975 · driest 5 mm in 1969	38
September	39.4°C3 Sep 2011	0.0°C23 Sep 1989	80 mm23 Sep 1993	238 mm1993 · driest 3 mm in 1979	39
October	34.4°C4 Oct 2006	-5.6°C30 Oct 1980	64 mm30 Oct 2009	297 mm2009 · driest 13 mm in 2010	37
November	29.4°C11 Nov 1989	-16.1°C24 Nov 1970	59 mm25 Nov 2010	236 mm1985 · driest 1 mm in 1976	38
December	26.1°C4 Dec 1970	-28.3°C22 Dec 1989	84 mm10 Dec 1971	228 mm1990 · driest 16 mm in 1979	39

Typical days per month at CAHOKIA, 1991–2020
Month	Days 25°C+	Days 30°C+	Frost nights	Heavy rain (10 mm+)	Snow days
January	0	0	24	2	3
February	<1	0	20	2	2
March	3	<1	13	3	1
April	7	1	3	4	<1
May	16	4	0	4	0
June	26	14	0	3	0
July	30	21	0	4	0
August	30	19	0	2	0
September	20	7	0	3	0
October	9	1	2	3	0
November	<1	0	11	3	<1
December	0	0	23	2	2

How often, not how much — every day in CAHOKIA’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%	20%	6%	20%	0.9–8.4°C
February	5%	21%	6%	21%	3.5–11.1°C
March	16%	28%	10%	34%	9.9–16.6°C
April	38%	30%	12%	40%	17.1–22.7°C
May	58%	31%	12%	36%	21.9–27.3°C
June	73%	26%	11%	29%	27.6–31.6°C
July	77%	23%	11%	21%	29.8–33.5°C
August	78%	22%	9%	20%	28.9–32.9°C
September	75%	20%	10%	20%	24.6–29.0°C
October	47%	22%	9%	22%	18.6–23.2°C
November	15%	24%	10%	24%	9.9–16.6°C
December	2%	22%	8%	21%	3.4–9.6°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.

1972Each stripe is one year’s mean temperature against the 30-year average. Warmest: 1998. Coolest: 1978.2010

The evidence behind this page

Nearby, measured,
and named.

Place identity: GeoNames 4234969
NOAA station: USC00111160 · CAHOKIA
Station distance: 0.6 km from the place centre
Climate period: 1991–2020
Minimum month coverage: 19 usable years
Daylight: Calculated from latitude 38.57°, 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 CAHOKIA is what differs

Oakville→Mehlville→Arnold→Lemay→Columbia→Dupo→

Or put two places side by side: Cahokia vs Oakville

Best time to visitCahokia.