United States · 1991–2020

Best time to visit
Willowbrook.

September leads for comfortable weather in Willowbrook: typically 24.3°C by day, 13°C at night, with 86 mm of rain. Based on measured 1991–2020 NOAA station history.

Best comfortSeptember

Typical high24.3°C

Typical low13°C

Rain in September86 mm

Comfort

September

September · June · August

84climate match

Beach

July

July · August · June

71climate match

Outdoors

May

May · October · September

72climate match

The weakest month is January, scoring 5 against September’s 84 — days reach only -0.5°C, 24° 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

5-0.5° / -8.8°

Feb

51.8° / -7°

Mar

87.9° / -1.8°

Apr

3615.2° / 4°

May

6321.3° / 9.9°

Jun

7326.8° / 15.4°

Jul

6228.8° / 18.1°

Aug

7027.8° / 17.1°

Sep

8424.3° / 13°

Oct

4917.3° / 6.3°

Nov

159.2° / 0.3°

Dec

52.4° / -5.4°

Monthly climate evidence for Willowbrook — daylight is calculated from latitude, everything else is measured, sea temperature from the nearest open water 23 km away
Month	Day	Night	Rain	Wet days	Sea	Daylight	Comfort	Coverage
January	-0.5°C	-8.8°C	64 mm	8.3	3.2°C	9 h 29	5	Strong coverage
February	1.8°C	-7°C	55 mm	7	1.7°C	10 h 32	5	Strong coverage
March	7.9°C	-1.8°C	64 mm	8	1.8°C	11 h 48	8	Strong coverage
April	15.2°C	4°C	102 mm	9.5	4.0°C	13 h 16	36	Strong coverage
May	21.3°C	9.9°C	119 mm	10.7	7.9°C	14 h 29	63	Strong coverage
June	26.8°C	15.4°C	123 mm	8.9	15.1°C	15 h 09	73	Strong coverage
July	28.8°C	18.1°C	120 mm	8	21.3°C	14 h 54	62	Strong coverage
August	27.8°C	17.1°C	105 mm	7.6	22.6°C	13 h 50	70	Strong coverage
September	24.3°C	13°C	86 mm	7	20.2°C	12 h 25	84	Strong coverage
October	17.3°C	6.3°C	92 mm	8.1	14.7°C	11 h 01	49	Strong coverage
November	9.2°C	0.3°C	74 mm	7.6	9.5°C	9 h 48	15	Strong coverage
December	2.4°C	-5.4°C	62 mm	8.1	5.8°C	9 h 11	5	Strong coverage

What has changed

Willowbrook runs +0.7°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

+1.2

Feb

+0.7

Mar

+1.2

Apr

-0.1

May

+0.4

Jun

+0.4

Jul

+0.3

Aug

+0.5

Sep

+1.2

Oct

+0.4

Nov

+0.1

Dec

+2.0

September daytime highs, 2011–2025. Last recorded: 26.2°C.

Records at PARK FOREST WATER, 1952–2026
Month	Record high	Record low	Wettest day	Wettest / driest month	Years
January	18.3°C24 Jan 1967	-32.8°C20 Jan 1985	88 mm8 Jan 2008	136 mm2005 · driest 2 mm in 1981	74
February	21.7°C26 Feb 2000	-29.4°C1 Feb 2019	63 mm20 Feb 2018	144 mm2018 · driest 1 mm in 1987	73
March	30.0°C22 Mar 2012	-21.1°C5 Mar 2002	50 mm7 Mar 2026	163 mm2009 · driest 6 mm in 1958	73
April	31.7°C27 Apr 1986	-12.8°C7 Apr 1982	99 mm17 Apr 2006	217 mm2013 · driest 12 mm in 1971	73
May	36.1°C28 May 2018	-3.9°C10 May 1966	163 mm22 May 1982	257 mm2019 · driest 24 mm in 1964	73
June	38.9°C26 Jun 1988	2.2°C11 Jun 1972	109 mm22 Jun 2018	312 mm2026 · driest 14 mm in 1965	74
July	38.9°C14 Jul 1995	7.2°C5 Jul 1972	166 mm18 Jul 1996	297 mm2003 · driest 14 mm in 1991	75
August	39.4°C2 Aug 1988	5.0°C29 Aug 1986	126 mm16 Aug 1968	238 mm2006 · driest 10 mm in 1996	74
September	37.2°C2 Sep 1953	-1.7°C23 Sep 1995	119 mm28 Sep 2019	338 mm2008 · driest 2 mm in 1979	74
October	32.8°C6 Oct 1963	-8.3°C29 Oct 1952	151 mm10 Oct 1954	257 mm1954 · driest 6 mm in 1964	72
November	25.0°C2 Nov 2016	-17.8°C30 Nov 1958	86 mm28 Nov 1990	210 mm1990 · driest 9 mm in 1976	73
December	21.1°C3 Dec 1982	-29.4°C25 Dec 1983	98 mm3 Dec 1982	174 mm1982 · driest 6 mm in 1962	74

Typical days per month at PARK FOREST WATER, 1991–2020
Month	Days 25°C+	Days 30°C+	Frost nights	Heavy rain (10 mm+)	Snow days
January	0	0	28	2	6
February	0	0	25	2	4
March	<1	0	21	2	2
April	2	<1	6	4	<1
May	10	3	<1	4	0
June	20	8	0	4	0
July	27	12	0	4	0
August	25	8	0	3	0
September	15	4	<1	3	0
October	4	<1	3	3	<1
November	0	0	15	2	1
December	0	0	26	2	3

How often, not how much — every day in PARK FOREST WATER’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%	23%	5%	21%	-4.6–2.3°C
February	<1%	22%	5%	21%	-2.4–5.3°C
March	4%	26%	7%	32%	4.7–11.4°C
April	17%	32%	12%	41%	12.5–17.7°C
May	42%	31%	12%	38%	18.6–24.6°C
June	66%	28%	13%	32%	24.9–28.8°C
July	74%	26%	12%	27%	27.3–30.7°C
August	75%	24%	10%	24%	26.2–29.8°C
September	63%	23%	9%	24%	22.3–26.5°C
October	28%	24%	8%	28%	15.5–19.8°C
November	5%	25%	8%	27%	5.9–11.9°C
December	0%	24%	6%	25%	-1.5–5.6°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.

1953Each stripe is one year’s mean temperature against the 67-year average. Warmest: 2012. Coolest: 2014.2025

The evidence behind this page

Nearby, measured,
and named.

Place identity: GeoNames 4916710
NOAA station: USC00116616 · PARK FOREST WATER
Station distance: 12.6 km from the place centre
Climate period: 1991–2020
Minimum month coverage: 29 usable years
Daylight: Calculated from latitude 41.46°, mid-month, sunrise to sunset including refraction. Not a station measurement.
Sea temperature: NOAA OISST v2.1 1991–2020 monthly climatology, nearest open water 23 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 PARK FOREST WATER is what differs

Hammond→Tinley Park→Calumet City→Chicago Heights→Schererville→East Chicago→

Or put two places side by side: Willowbrook vs Hammond

Best time to visitWillowbrook.

September

July

May

The whole year,without the guesswork.

Willowbrook runs +0.7°Con the 1961–1990 baseline.

Nearby, measured,and named.

Best time to visit
Willowbrook.

The whole year,
without the guesswork.

Willowbrook runs +0.7°C
on the 1961–1990 baseline.

Nearby, measured,
and named.