United Kingdom · 1991–2020

Best time to visit
Caernarfon.

July leads for comfortable weather in Caernarfon: typically 18.7°C by day, 12.9°C at night, with 57 mm of rain. Based on measured 1991–2020 NOAA station history.

Best comfortJuly

Typical high18.7°C

Typical low12.9°C

Rain in July57 mm

Comfort

July

July · August · June

69climate match

Beach

July

July · August · June

35climate match

Outdoors

June

June · July · August

78climate match

The weakest month is December, scoring 10 against July’s 69 — days reach only 9.1°C, 15° 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

138.4° / 3.7°

Feb

168.5° / 3.6°

Mar

239.9° / 4.5°

Apr

3412.1° / 6°

May

5115.1° / 8.5°

Jun

6117.3° / 11°

Jul

6918.7° / 12.9°

Aug

6718.7° / 13.1°

Sep

5817.2° / 11.5°

Oct

3714.3° / 9.1°

Nov

2011.3° / 6.4°

Dec

109.1° / 4.2°

Monthly climate evidence for Caernarfon — daylight is calculated from latitude, everything else is measured, sea temperature from the nearest open water 24 km away
Month	Day	Night	Rain	Wet days	Sea	Daylight	Comfort	Coverage
January	8.4°C	3.7°C	74 mm	14.5	9.2°C	8 h 03	13	Strong coverage
February	8.5°C	3.6°C	63 mm	12.2	8.3°C	9 h 44	16	Strong coverage
March	9.9°C	4.5°C	59 mm	11.9	8.1°C	11 h 40	23	Strong coverage
April	12.1°C	6°C	57 mm	11.4	8.9°C	13 h 53	34	Strong coverage
May	15.1°C	8.5°C	53 mm	9.4	10.4°C	15 h 48	51	Strong coverage
June	17.3°C	11°C	56 mm	9.7	12.3°C	16 h 55	61	Strong coverage
July	18.7°C	12.9°C	57 mm	10.9	14.0°C	16 h 28	69	Strong coverage
August	18.7°C	13.1°C	70 mm	11.2	15.2°C	14 h 46	67	Strong coverage
September	17.2°C	11.5°C	75 mm	11.3	15.2°C	12 h 36	58	Strong coverage
October	14.3°C	9.1°C	104 mm	14.8	14.3°C	10 h 28	37	Strong coverage
November	11.3°C	6.4°C	106 mm	17.1	12.5°C	8 h 33	20	Strong coverage
December	9.1°C	4.2°C	100 mm	16.6	10.7°C	7 h 34	10	Strong coverage

What has changed

Caernarfon runs +0.9°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

+0.9

Feb

+1.3

Mar

+1.2

Apr

+1.4

May

+1.1

Jun

+0.9

Jul

+0.7

Aug

+0.4

Sep

+0.7

Oct

+0.4

Nov

+1.1

Dec

+1.2

July daytime highs, 2011–2025. Last recorded: 19.9°C.

Records at VALLEY, 1930–2026
Month	Record high	Record low	Wettest day	Wettest / driest month	Years
January	14.8°C10 Jan 1971	-12.2°C26 Jan 1945	91 mm4 Jan 1987	159 mm2014 · driest 7 mm in 1997	96
February	18.8°C25 Feb 2019	-12.2°C2 Feb 1956	33 mm10 Feb 1977	145 mm1977 · driest 7 mm in 1986	96
March	20.6°C23 Mar 1945	-8.3°C10 Mar 1958	39 mm22 Mar 1981	133 mm1981 · driest 4 mm in 1990	96
April	24.3°C29 Apr 2026	-2.8°C2 Apr 1984	27 mm1 Apr 1994	101 mm2005 · driest 2 mm in 1984	96
May	29.2°C26 May 2026	-0.3°C7 May 1982	30 mm19 May 2006	111 mm2015 · driest 1 mm in 1991	96
June	30.6°C6 Jun 1950	1.2°C1 Jun 1962	43 mm5 Jun 2017	129 mm2017 · driest 7 mm in 1992	96
July	29.4°C31 Jul 1943	3.9°C6 Jul 1954	54 mm28 Jul 1988	127 mm2010 · driest 3 mm in 1983	95
August	29.7°C11 Aug 2022	5.0°C31 Aug 1986	46 mm5 Aug 2014	121 mm1985 · driest 9 mm in 1995	95
September	28.2°C4 Sep 2005	1.8°C19 Sep 1986	43 mm24 Sep 2012	150 mm1999 · driest 8 mm in 2014	95
October	25.0°C4 Oct 1959	-1.7°C30 Oct 2018	59 mm3 Oct 2014	208 mm2000 · driest 25 mm in 2016	95
November	18.8°C12 Nov 2022	-5.0°C29 Nov 2010	92 mm14 Nov 1984	221 mm2000 · driest 24 mm in 1983	95
December	15.6°C18 Dec 1972	-9.3°C25 Dec 2010	54 mm19 Dec 1993	254 mm2015 · driest 4 mm in 1995	96

Typical days per month at VALLEY, 1991–2020
Month	Days 25°C+	Frost nights	Heavy rain (10 mm+)
January	0	5	2
February	0	5	2
March	0	3	1
April	0	<1	1
May	<1	0	1
June	<1	0	2
July	1	0	1
August	<1	0	2
September	<1	0	2
October	0	<1	3
November	0	<1	3
December	0	5	3

How often, not how much — every day in VALLEY’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%	49%	6%	65%	6.7–9.5°C
February	0%	43%	5%	58%	6.5–9.5°C
March	<1%	40%	4%	53%	8.1–11.2°C
April	2%	35%	3%	44%	10.2–13.4°C
May	8%	31%	4%	40%	13.0–16.4°C
June	15%	32%	5%	42%	15.5–18.5°C
July	22%	32%	5%	44%	16.9–20.1°C
August	18%	35%	6%	47%	17.3–20.3°C
September	8%	40%	8%	57%	15.8–18.3°C
October	<1%	49%	10%	69%	13.0–15.6°C
November	0%	55%	11%	76%	10.0–12.1°C
December	0%	53%	9%	72%	7.5–10.4°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.

1931Each stripe is one year’s mean temperature against the 94-year average. Warmest: 2023. Coolest: 1963.2025

The evidence behind this page

Nearby, measured,
and named.

Place identity: GeoNames 2654092
NOAA station: UK000003302 · VALLEY
Station distance: 21.3 km from the place centre
Climate period: 1991–2020
Minimum month coverage: 29 usable years
Daylight: Calculated from latitude 53.14°, mid-month, sunrise to sunset including refraction. Not a station measurement.
Sea temperature: NOAA OISST v2.1 1991–2020 monthly climatology, nearest open water 24 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 VALLEY is what differs

Bangor→Holyhead→Llangefni→Bethesda→Pwllheli→Menai Bridge→

Or put two places side by side: Caernarfon vs Bangor

Best time to visitCaernarfon.

July

July

June

The whole year,without the guesswork.

Caernarfon runs +0.9°Con the 1961–1990 baseline.

Nearby, measured,and named.

Best time to visit
Caernarfon.

The whole year,
without the guesswork.

Caernarfon runs +0.9°C
on the 1961–1990 baseline.

Nearby, measured,
and named.