United States · 1991–2020

Best time to visit
Eureka.

September leads for comfortable weather in Eureka: typically 27.1°C by day, 13.7°C at night, with 80 mm of rain. Based on measured 1991–2020 NOAA station history.

Best comfortSeptember

Typical high27.1°C

Typical low13.7°C

Rain in September80 mm

Comfort

September

September · May · October

78climate match

Beach

July

July · August · June

76climate match

Outdoors

October

October · April · September

81climate match

The weakest month is January, scoring 5 against September’s 78 — days reach only 4.9°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

54.9° / -5.5°

Feb

97.8° / -3.5°

Mar

3014° / 1.5°

Apr

5720.2° / 7°

May

7525° / 12.8°

Jun

6129.7° / 17.7°

Jul

5531.8° / 20.1°

Aug

5931° / 18.7°

Sep

7827.1° / 13.7°

Oct

6520.6° / 7.3°

Nov

3213.6° / 1.5°

Dec

57.3° / -3.2°

Monthly climate evidence for Eureka — daylight is calculated from latitude, everything else is measured
Month	Day	Night	Rain	Wet days	Daylight	Comfort	Coverage
January	4.9°C	-5.5°C	59 mm	5.7	9 h 45	5	Strong coverage
February	7.8°C	-3.5°C	49 mm	5.9	10 h 42	9	Strong coverage
March	14°C	1.5°C	87 mm	8.3	11 h 50	30	Strong coverage
April	20.2°C	7°C	113 mm	9.3	13 h 09	57	Strong coverage
May	25°C	12.8°C	117 mm	10	14 h 15	75	Strong coverage
June	29.7°C	17.7°C	110 mm	8.6	14 h 50	61	Strong coverage
July	31.8°C	20.1°C	87 mm	6.8	14 h 36	55	Strong coverage
August	31°C	18.7°C	88 mm	6.9	13 h 40	59	Strong coverage
September	27.1°C	13.7°C	80 mm	6	12 h 23	78	Strong coverage
October	20.6°C	7.3°C	81 mm	6.7	11 h 07	65	Strong coverage
November	13.6°C	1.5°C	82 mm	6.9	10 h 02	32	Strong coverage
December	7.3°C	-3.2°C	61 mm	6.5	9 h 29	5	Strong coverage

Records at ST LOUIS SPIRIT OF ST LOUIS AP, 1987–2026
Month	Record high	Record low	Wettest day	Wettest / driest month	Years
January	24.4°C28 Jan 2002	-26.7°C5 Jan 1999	68 mm13 Jan 1995	211 mm2005 · driest 7 mm in 2026	36
February	28.9°C27 Feb 2024	-24.3°C7 Feb 2014	63 mm18 Feb 2000	117 mm2018 · driest 1 mm in 2024	37
March	34.4°C26 Mar 2026	-17.2°C4 Mar 2002	68 mm26 Mar 2004	187 mm2008 · driest 38 mm in 1994	37
April	34.4°C18 Apr 2002	-6.1°C7 Apr 1990	108 mm4 Apr 2025	285 mm1994 · driest 49 mm in 2006	36
May	35.0°C26 May 2012	-0.6°C6 May 1992	105 mm7 May 2000	284 mm1990 · driest 28 mm in 2012	37
June	42.8°C28 Jun 2012	7.2°C5 Jun 1993	97 mm24 Jun 2000	234 mm2015 · driest 23 mm in 1991	37
July	42.2°C7 Jul 2012	10.0°C28 Jul 2013	90 mm9 Jul 1991	283 mm2024 · driest 18 mm in 2012	37
August	41.1°C15 Aug 2007	7.8°C13 Aug 2004	105 mm6 Aug 1995	200 mm2019 · driest 19 mm in 2013	35
September	38.3°C1 Sep 2011	0.0°C24 Sep 1989	114 mm14 Sep 2008	276 mm1993 · driest 5 mm in 2004	36
October	34.4°C3 Oct 2006	-4.9°C31 Oct 2023	68 mm8 Oct 2009	302 mm2009 · driest 20 mm in 2024	36
November	29.4°C1 Nov 2016	-15.0°C8 Nov 1991	79 mm4 Nov 2024	174 mm2024 · driest 3 mm in 2012	36
December	25.0°C28 Dec 2025	-30.0°C23 Dec 1989	105 mm26 Dec 2015	261 mm2015 · driest 6 mm in 2025	36

Typical days per month at ST LOUIS SPIRIT OF ST LOUIS AP, 1991–2020
Month	Days 25°C+	Days 30°C+	Frost nights	Heavy rain (10 mm+)	Snow days
January	0	0	26	2	1
February	<1	0	22	2	<1
March	3	<1	14	3	<1
April	8	2	4	4	<1
May	17	6	0	4	0
June	27	16	0	4	0
July	30	23	0	3	0
August	30	20	0	3	0
September	21	9	0	2	0
October	8	2	3	3	0
November	1	0	13	3	<1
December	0	0	23	2	<1

How often, not how much — every day in ST LOUIS SPIRIT OF ST LOUIS 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	2%	18%	6%	14%	2.0–8.5°C
February	6%	21%	6%	19%	3.0–11.5°C
March	19%	28%	10%	31%	11.2–17.9°C
April	38%	31%	14%	37%	18.3–22.6°C
May	58%	32%	12%	39%	22.8–27.1°C
June	73%	27%	12%	31%	28.2–31.7°C
July	77%	23%	9%	21%	29.9–33.3°C
August	78%	22%	9%	22%	29.6–32.8°C
September	76%	19%	8%	17%	24.7–29.1°C
October	47%	21%	8%	20%	18.5–22.9°C
November	16%	22%	8%	22%	10.3–16.4°C
December	3%	22%	6%	23%	4.6–10.1°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.

1989Each stripe is one year’s mean temperature against the 32-year average. Warmest: 2012. Coolest: 2014.2025

The evidence behind this page

Nearby, measured,
and named.

Place identity: GeoNames 4385835
NOAA station: USW00003966 · ST LOUIS SPIRIT OF ST LOUIS AP
Station distance: 17.4 km from the place centre
Climate period: 1991–2020
Minimum month coverage: 27 usable years
Daylight: Calculated from latitude 38.50°, 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 ST LOUIS SPIRIT OF ST LOUIS AP is what differs

Wildwood→Ellisville→Pacific→High Ridge→Byrnes Mill→Clarkson Valley→

Or put two places side by side: Eureka vs Wildwood

Best time to visitEureka.