United States · 1991–2020

Best time to visit
Mount Prospect.

September leads for comfortable weather in Mount Prospect: typically 24.2°C by day, 13.3°C at night, with 76 mm of rain. Based on measured 1991–2020 NOAA station history.

Best comfortSeptember

Typical high24.2°C

Typical low13.3°C

Rain in September76 mm

Comfort

September

September · June · August

88climate match

Beach

July

July · August · June

80climate match

Outdoors

May

May · September · October

77climate match

The weakest month is January, scoring 5 against September’s 88 — days reach only -0.1°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

5-0.1° / -8°

Feb

52° / -6.5°

Mar

148.1° / -1.4°

Apr

3714.5° / 3.6°

May

6320.7° / 9.4°

Jun

7726.3° / 15.2°

Jul

6828.8° / 18.3°

Aug

7227.7° / 17.6°

Sep

8824.2° / 13.3°

Oct

5016.8° / 6.5°

Nov

219.3° / 0.4°

Dec

52.5° / -5°

Monthly climate evidence for Mount Prospect — daylight is calculated from latitude, everything else is measured, sea temperature from the nearest open water 27 km away
Month	Day	Night	Rain	Wet days	Sea	Daylight	Comfort	Coverage
January	-0.1°C	-8°C	31 mm	4.6	3.4°C	9 h 25	5	Good coverage
February	2°C	-6.5°C	31 mm	4.2	2.2°C	10 h 30	5	Good coverage
March	8.1°C	-1.4°C	45 mm	6.1	2.2°C	11 h 48	14	Good coverage
April	14.5°C	3.6°C	78 mm	8.9	3.7°C	13 h 17	37	Good coverage
May	20.7°C	9.4°C	105 mm	9.9	6.6°C	14 h 32	63	Good coverage
June	26.3°C	15.2°C	104 mm	8.7	13.5°C	15 h 14	77	Good coverage
July	28.8°C	18.3°C	82 mm	6.5	20.7°C	14 h 57	68	Good coverage
August	27.7°C	17.6°C	87 mm	7.2	22.4°C	13 h 52	72	Good coverage
September	24.2°C	13.3°C	76 mm	6.3	20.0°C	12 h 26	88	Good coverage
October	16.8°C	6.5°C	81 mm	8	14.3°C	11 h	50	Good coverage
November	9.3°C	0.4°C	48 mm	6	9.0°C	9 h 44	21	Good coverage
December	2.5°C	-5°C	44 mm	6.1	5.6°C	9 h 07	5	Good coverage

Records at CHICAGO PALWAUKEE AP, 1996–2026
Month	Record high	Record low	Wettest day	Wettest / driest month	Years
January	18.3°C7 Jan 2008	-29.3°C30 Jan 2019	38 mm29 Jan 2013	91 mm2013 · driest 2 mm in 2011	30
February	23.9°C27 Feb 2024	-24.3°C28 Feb 2015	39 mm20 Feb 2018	88 mm2023 · driest 0 mm in 2015	30
March	30.0°C20 Mar 2012	-19.9°C3 Mar 2014	40 mm30 Mar 2017	102 mm2026 · driest 11 mm in 2005	30
April	31.1°C27 Apr 2021	-6.7°C9 Apr 1997	51 mm20 Apr 2000	232 mm1999 · driest 11 mm in 2005	30
May	36.1°C27 May 2018	-1.7°C3 May 2004	66 mm17 May 2020	204 mm2018 · driest 18 mm in 2023	30
June	37.2°C14 Jun 2022	2.8°C1 Jun 2003	115 mm26 Jun 2013	248 mm2018 · driest 7 mm in 2005	30
July	40.0°C6 Jul 2012	10.0°C2 Jul 2001	86 mm23 Jul 2011	207 mm2011 · driest 0 mm in 2002	31
August	37.8°C24 Aug 2023	8.3°C31 Aug 2009	54 mm4 Aug 2014	252 mm2007 · driest 0 mm in 2002	30
September	35.6°C10 Sep 2013	1.1°C24 Sep 2012	111 mm13 Sep 2008	240 mm2008 · driest 8 mm in 2004	29
October	31.7°C5 Oct 1997	-3.8°C31 Oct 2023	90 mm13 Oct 2001	208 mm2017 · driest 6 mm in 2005	30
November	24.4°C10 Nov 2022	-12.7°C12 Nov 2019	40 mm2 Nov 2003	128 mm2003 · driest 9 mm in 1999	30
December	20.6°C3 Dec 2012	-22.2°C22 Dec 2000	36 mm1 Dec 2006	109 mm2008 · driest 7 mm in 2017	30

Typical days per month at CHICAGO PALWAUKEE AP, 1991–2020
Month	Days 25°C+	Days 30°C+	Frost nights	Heavy rain (10 mm+)
January	0	0	28	<1
February	0	0	25	1
March	<1	<1	20	1
April	2	<1	6	3
May	9	3	<1	4
June	19	8	0	3
July	26	13	0	2
August	24	8	0	3
September	13	4	0	2
October	3	<1	2	2
November	0	0	15	2
December	0	0	26	1

How often, not how much — every day in CHICAGO PALWAUKEE AP’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%	15%	3%	12%	-2.4–3.4°C
February	<1%	15%	3%	9%	-2.4–6.3°C
March	6%	22%	5%	27%	5.8–12.0°C
April	16%	30%	9%	36%	13.0–17.2°C
May	40%	30%	11%	38%	18.6–23.3°C
June	66%	29%	10%	34%	24.8–28.5°C
July	77%	23%	9%	23%	26.7–31.0°C
August	76%	23%	9%	25%	26.0–29.5°C
September	66%	20%	7%	20%	22.4–26.2°C
October	25%	26%	8%	25%	15.4–19.3°C
November	5%	20%	5%	18%	5.6–12.8°C
December	0%	20%	5%	15%	-0.5–6.1°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.

1998Each stripe is one year’s mean temperature against the 28-year average. Warmest: 2024. Coolest: 2014.2025

The evidence behind this page

Nearby, measured,
and named.

Place identity: GeoNames 4903024
NOAA station: USW00004838 · CHICAGO PALWAUKEE AP
Station distance: 6.6 km from the place centre
Climate period: 1991–2020
Minimum month coverage: 22 usable years
Daylight: Calculated from latitude 42.07°, mid-month, sunrise to sunset including refraction. Not a station measurement.
Sea temperature: NOAA OISST v2.1 1991–2020 monthly climatology, nearest open water 27 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 CHICAGO PALWAUKEE AP is what differs

Arlington Heights→Buffalo Grove→Wheeling→Rolling Meadows→Prospect Heights→Long Grove→

Or put two places side by side: Mount Prospect vs Arlington Heights

Best time to visitMount Prospect.

September

July

May

The whole year,without the guesswork.

Nearby, measured,and named.

Best time to visit
Mount Prospect.

The whole year,
without the guesswork.

Nearby, measured,
and named.