United States · 1991–2020

Best time to visit
Fairfield.

September leads for comfortable weather in Fairfield: typically 23.7°C by day, 11.9°C at night, with 95 mm of rain. Based on measured 1991–2020 NOAA station history.

Best comfortSeptember

Typical high23.7°C

Typical low11.9°C

Rain in September95 mm

Comfort

September

September · June · August

81climate match

Beach

July

July · August · June

69climate match

Outdoors

May

May · September · October

73climate match

The weakest month is January, scoring 5 against September’s 81 — days reach only -1.2°C, 25° 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

5-1.2° / -10°

Feb

50.4° / -9.3°

Mar

57.1° / -3.4°

Apr

3014.1° / 2.3°

May

5620° / 8.6°

Jun

7625.5° / 14.3°

Jul

6928.1° / 17°

Aug

7427.3° / 16.1°

Sep

8123.7° / 11.9°

Oct

4516.1° / 5.3°

Nov

158.6° / -0.8°

Dec

51.4° / -7.1°

Monthly climate evidence for Fairfield — 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	-1.2°C	-10°C	43 mm	6.9	3.4°C	9 h 25	5	Good coverage
February	0.4°C	-9.3°C	52 mm	7.3	2.2°C	10 h 30	5	Good coverage
March	7.1°C	-3.4°C	66 mm	7.8	2.1°C	11 h 48	5	Good coverage
April	14.1°C	2.3°C	97 mm	9.6	3.5°C	13 h 18	30	Good coverage
May	20°C	8.6°C	124 mm	10.6	6.2°C	14 h 33	56	Good coverage
June	25.5°C	14.3°C	116 mm	9.9	12.9°C	15 h 15	76	Good coverage
July	28.1°C	17°C	106 mm	7.6	20.1°C	14 h 58	69	Good coverage
August	27.3°C	16.1°C	96 mm	7.9	21.8°C	13 h 53	74	Good coverage
September	23.7°C	11.9°C	95 mm	7.4	19.4°C	12 h 26	81	Good coverage
October	16.1°C	5.3°C	82 mm	8.1	13.8°C	10 h 59	45	Good coverage
November	8.6°C	-0.8°C	57 mm	6.5	8.5°C	9 h 44	15	Good coverage
December	1.4°C	-7.1°C	58 mm	7.9	5.3°C	9 h 06	5	Good coverage

Records at MUNDELEIN 4WSW, 1999–2024
Month	Record high	Record low	Wettest day	Wettest / driest month	Years
January	17.2°C8 Jan 2008	-32.2°C31 Jan 2019	36 mm17 Jan 2017	92 mm2005 · driest 9 mm in 2003	25
February	23.9°C28 Feb 2024	-32.2°C1 Feb 2019	43 mm25 Feb 2007	131 mm2008 · driest 5 mm in 2003	25
March	28.9°C22 Mar 2012	-23.9°C1 Mar 2015	55 mm21 Mar 2011	128 mm2004 · driest 18 mm in 2005	25
April	31.7°C19 Apr 2002	-9.4°C8 Apr 2018	105 mm18 Apr 2013	208 mm2013 · driest 20 mm in 2021	25
May	34.4°C28 May 2018	-3.9°C9 May 2020	84 mm13 May 2010	222 mm2004 · driest 25 mm in 2023	24
June	36.7°C29 Jun 2012	1.7°C1 Jun 2003	82 mm11 Jun 2014	244 mm2018 · driest 18 mm in 2005	24
July	39.4°C7 Jul 2012	6.7°C2 Jul 2001	82 mm24 Jul 2010	281 mm2017 · driest 19 mm in 2002	24
August	36.1°C22 Aug 2003	7.2°C15 Aug 2004	106 mm22 Aug 2002	317 mm2007 · driest 27 mm in 2003	24
September	34.4°C11 Sep 2013	1.1°C24 Sep 2012	90 mm12 Sep 2022	270 mm2019 · driest 6 mm in 2017	24
October	30.6°C10 Oct 2010	-5.6°C31 Oct 2020	60 mm23 Oct 2001	194 mm2017 · driest 13 mm in 2005	24
November	23.9°C2 Nov 2016	-15.6°C21 Nov 2014	37 mm3 Nov 2016	133 mm2003 · driest 14 mm in 2012	24
December	20.0°C6 Dec 2001	-24.4°C23 Dec 2022	46 mm29 Dec 2015	145 mm2015 · driest 17 mm in 2014	25

Typical days per month at MUNDELEIN 4WSW, 1991–2020
Month	Days 25°C+	Days 30°C+	Frost nights	Heavy rain (10 mm+)	Snow days
January	0	0	29	1	9
February	0	0	27	2	8
March	<1	0	23	2	4
April	2	<1	10	3	1
May	8	2	<1	4	0
June	18	6	0	3	0
July	26	10	0	3	0
August	24	7	0	3	0
September	13	4	0	3	0
October	3	<1	5	3	0
November	0	0	18	2	2
December	0	0	28	2	7

How often, not how much — every day in MUNDELEIN 4WSW’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%	24%	4%	25%	-3.6–1.5°C
February	<1%	26%	6%	27%	-4.8–4.7°C
March	3%	25%	7%	29%	4.3–10.1°C
April	15%	32%	10%	39%	11.7–16.7°C
May	37%	33%	13%	42%	18.1–22.4°C
June	62%	32%	11%	42%	24.2–27.2°C
July	75%	25%	10%	24%	26.1–30.1°C
August	74%	25%	10%	25%	25.6–28.7°C
September	59%	24%	10%	30%	22.1–25.6°C
October	22%	26%	8%	29%	14.1–18.8°C
November	5%	21%	6%	23%	4.7–12.1°C
December	0%	25%	6%	27%	-2.1–5.0°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.

2000Each stripe is one year’s mean temperature against the 24-year average. Warmest: 2012. Coolest: 2014.2023

The evidence behind this page

Nearby, measured,
and named.

Place identity: GeoNames 4891534
NOAA station: USC00115961 · MUNDELEIN 4WSW
Station distance: 4.2 km from the place centre
Climate period: 1991–2020
Minimum month coverage: 21 usable years
Daylight: Calculated from latitude 42.22°, 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 MUNDELEIN 4WSW is what differs

Mundelein→Vernon Hills→Lake Zurich→Wauconda→Hawthorn Woods→Lake Barrington→

Or put two places side by side: Fairfield vs Mundelein

Best time to visitFairfield.

September

July

May

The whole year,without the guesswork.

Nearby, measured,and named.

Best time to visit
Fairfield.

The whole year,
without the guesswork.

Nearby, measured,
and named.