United States · 1991–2020

Best time to visit
Upper Lake.

May leads for comfortable weather in Upper Lake: typically 25.6°C by day, 8.6°C at night, with 24 mm of rain. Based on measured 1991–2020 NOAA station history.

Best comfortMay

Typical high25.6°C

Typical low8.6°C

Rain in May24 mm

Comfort

May

May · October · June

83climate match

Beach

June

June · September · July

70climate match

Outdoors

April

April · May · October

83climate match

The weakest month is December, scoring 12 against May’s 83 — days reach only 13.5°C, 10° below the 24°C the score treats as ideal, and 199 mm of rain falls.

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

2514.5° / 2.6°

Feb

3316.2° / 3.2°

Mar

4418.2° / 4.7°

Apr

6520.5° / 5.9°

May

8325.6° / 8.6°

Jun

7330.1° / 11.4°

Jul

6234.6° / 13.4°

Aug

6333.9° / 12.7°

Sep

6731.4° / 10.3°

Oct

7925.7° / 7.2°

Nov

4918° / 4.2°

Dec

1213.5° / 2.5°

Monthly climate evidence for Upper Lake — daylight is calculated from latitude, everything else is measured
Month	Day	Night	Rain	Wet days	Daylight	Comfort	Coverage
January	14.5°C	2.6°C	142 mm	10.2	9 h 42	25	Good coverage
February	16.2°C	3.2°C	139 mm	8.9	10 h 40	33	Good coverage
March	18.2°C	4.7°C	120 mm	10.3	11 h 50	44	Good coverage
April	20.5°C	5.9°C	62 mm	6.5	13 h 10	65	Good coverage
May	25.6°C	8.6°C	24 mm	3	14 h 18	83	Good coverage
June	30.1°C	11.4°C	7 mm	1	14 h 54	73	Good coverage
July	34.6°C	13.4°C	0 mm	0.1	14 h 40	62	Good coverage
August	33.9°C	12.7°C	0 mm	0.1	13 h 42	63	Good coverage
September	31.4°C	10.3°C	4 mm	0.9	12 h 24	67	Good coverage
October	25.7°C	7.2°C	43 mm	3.8	11 h 06	79	Good coverage
November	18°C	4.2°C	90 mm	7.9	9 h 59	49	Good coverage
December	13.5°C	2.5°C	199 mm	12.3	9 h 26	12	Good coverage

Records at UKIAH MUNI AP, 1949–2026
Month	Record high	Record low	Wettest day	Wettest / driest month	Years
January	26.7°C18 Jan 2021	-7.1°C13 Jan 2007	79 mm4 Jan 2008	379 mm2017 · driest 12 mm in 2015	26
February	28.9°C3 Feb 2018	-4.3°C20 Feb 2018	88 mm25 Feb 2019	405 mm2019 · driest 0 mm in 2020	26
March	34.4°C20 Mar 2026	-2.7°C7 Mar 2012	71 mm27 Mar 2012	296 mm2011 · driest 2 mm in 2026	26
April	36.1°C21 Apr 2009	-0.6°C8 Apr 2001	61 mm6 Apr 2018	217 mm2003 · driest 7 mm in 2021	26
May	41.1°C31 May 2021	1.7°C23 May 2010	31 mm18 May 2005	103 mm2005 · driest 0 mm in 2021	26
June	43.9°C22 Jun 2017	4.4°C7 Jun 2005	28 mm8 Jun 2005	47 mm2005 · driest 0 mm in 2025	26
July	47.2°C6 Jul 2024	7.8°C2 Jul 2003	3 mm9 Jul 2015	3 mm2015 · driest 0 mm in 2020	26
August	43.3°C1 Aug 2017	7.2°C29 Aug 2010	2 mm17 Aug 2020	2 mm2020 · driest 0 mm in 2011	25
September	47.2°C6 Sep 2022	3.3°C26 Sep 2013	48 mm18 Sep 2022	50 mm2022 · driest 0 mm in 2012	26
October	41.7°C2 Oct 2024	-3.3°C19 Oct 1949	127 mm24 Oct 2021	182 mm2021 · driest 0 mm in 2002	27
November	31.1°C2 Nov 2020	-7.1°C29 Nov 2015	93 mm21 Nov 2024	280 mm2024 · driest 18 mm in 2007	25
December	28.9°C3 Dec 2006	-7.7°C9 Dec 2013	111 mm30 Dec 2005	509 mm2002 · driest 4 mm in 2017	25

Typical days per month at UKIAH MUNI AP, 1991–2020
Month	Days 25°C+	Days 30°C+	Frost nights	Heavy rain (10 mm+)
January	<1	0	10	5
February	1	0	7	4
March	5	<1	2	4
April	8	3	<1	2
May	17	8	0	<1
June	25	17	0	<1
July	31	27	0	0
August	31	26	0	0
September	26	20	0	<1
October	18	9	<1	2
November	3	<1	5	3
December	<1	0	11	6

How often, not how much — every day in UKIAH MUNI 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	14%	33%	14%	42%	12.8–17.3°C
February	26%	32%	15%	44%	13.8–20.1°C
March	38%	33%	12%	40%	14.6–22.4°C
April	53%	20%	6%	22%	18.4–23.5°C
May	83%	9%	2%	7%	23.6–27.9°C
June	96%	3%	<1%	2%	28.3–32.7°C
July	100%	<1%	0%	0%	33.4–36.4°C
August	100%	<1%	<1%	0%	32.9–35.9°C
September	95%	4%	<1%	3%	29.4–33.4°C
October	79%	13%	5%	14%	22.9–28.5°C
November	32%	26%	10%	35%	16.2–19.9°C
December	4%	41%	21%	55%	12.0–16.0°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.

2001Each stripe is one year’s mean temperature against the 25-year average. Warmest: 2024. Coolest: 2011.2025

The evidence behind this page

Nearby, measured,
and named.

Place identity: GeoNames 5405038
NOAA station: USW00023275 · UKIAH MUNI AP
Station distance: 25.3 km from the place centre
Climate period: 1991–2020
Minimum month coverage: 20 usable years
Daylight: Calculated from latitude 39.16°, 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 UKIAH MUNI AP is what differs

Lakeport→North Lakeport→Nice→Talmage→Boonville→Hopland→

Or put two places side by side: Upper Lake vs Lakeport

Best time to visitUpper Lake.

May

June

April

The whole year,without the guesswork.

Nearby, measured,and named.

Best time to visit
Upper Lake.

The whole year,
without the guesswork.

Nearby, measured,
and named.