Japan · 1991–2020

Best time to visit
Isahaya.

October leads for comfortable weather in Isahaya: typically 24.1°C by day, 15.9°C at night, with 136 mm of rain. Based on measured 1991–2020 NOAA station history.

Best comfortOctober

Typical high24.1°C

Typical low15.9°C

Rain in October136 mm

Comfort

October

October · May · November

81climate match

Beach

September

September · October · May

56climate match

Outdoors

November

November · April · October

77climate match

The weakest month is July, scoring 9 against October’s 81 — 345 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

2310.5° / 3.4°

Feb

2612° / 3.5°

Mar

3615.3° / 6.7°

Apr

5719.8° / 11.2°

May

6923.8° / 15.6°

Jun

2026.4° / 19.8°

Jul

930.4° / 24.2°

Aug

1531.9° / 25.2°

Sep

3928.9° / 21.6°

Oct

8124.1° / 15.9°

Nov

5918.5° / 10.2°

Dec

3313.2° / 5.5°

Monthly climate evidence for Isahaya — daylight is calculated from latitude, everything else is measured, sea temperature from the nearest open water 25 km away
Month	Day	Night	Rain	Wet days	Sea	Daylight	Comfort	Coverage
January	10.5°C	3.4°C	73 mm	10.4	16.0°C	10 h 12	23	Good coverage
February	12°C	3.5°C	94 mm	9	14.8°C	10 h 58	26	Good coverage
March	15.3°C	6.7°C	129 mm	10.4	15.4°C	11 h 53	36	Good coverage
April	19.8°C	11.2°C	154 mm	9	16.9°C	12 h 57	57	Good coverage
May	23.8°C	15.6°C	191 mm	10.8	19.3°C	13 h 50	69	Good coverage
June	26.4°C	19.8°C	409 mm	15	22.2°C	14 h 18	20	Good coverage
July	30.4°C	24.2°C	345 mm	13.8	25.3°C	14 h 07	9	Good coverage
August	31.9°C	25.2°C	269 mm	11.3	27.4°C	13 h 22	15	Good coverage
September	28.9°C	21.6°C	225 mm	10.7	26.4°C	12 h 20	39	Good coverage
October	24.1°C	15.9°C	136 mm	5.9	23.7°C	11 h 18	81	Good coverage
November	18.5°C	10.2°C	106 mm	7.8	20.8°C	10 h 25	59	Good coverage
December	13.2°C	5.5°C	93 mm	10.2	18.1°C	10 h	33	Good coverage

Records at NAGASAKI, 1951–2026
Month	Record high	Record low	Wettest day	Wettest / driest month	Years
January	20.5°C29 Jan 2017	-4.4°C25 Jan 2016	82 mm14 Jan 2023	237 mm1972 · driest 0 mm in 2026	75
February	22.6°C24 Feb 2010	-4.3°C16 Feb 1977	100 mm23 Feb 1979	192 mm1989 · driest 0 mm in 2026	75
March	24.4°C18 Mar 1952	-3.6°C5 Mar 1977	238 mm24 Mar 2024	327 mm2024 · driest 0 mm in 2026	75
April	29.0°C29 Apr 1998	1.2°C2 Apr 1972	144 mm22 Apr 1958	383 mm1958 · driest 0 mm in 2025	75
May	31.4°C23 May 1998	4.0°C1 May 2026	196 mm8 May 1973	400 mm1953 · driest 0 mm in 2025	75
June	36.4°C20 Jun 2004	12.0°C10 Jun 1951	245 mm30 Jun 1981	772 mm2011 · driest 0 mm in 2025	75
July	37.7°C23 Jul 1994	14.9°C8 Jul 2026	448 mm23 Jul 1982	1179 mm1982 · driest 0 mm in 2025	75
August	37.6°C17 Aug 1964	18.8°C19 Aug 1956	252 mm16 Aug 1956	940 mm2021 · driest 0 mm in 2025	74
September	36.1°C12 Sep 1961	11.7°C29 Sep 1965	243 mm25 Sep 1954	507 mm1999 · driest 0 mm in 2025	74
October	33.7°C3 Oct 1961	4.9°C31 Oct 1970	181 mm8 Oct 1981	279 mm2017 · driest 0 mm in 2025	74
November	26.3°C3 Nov 2011	0.9°C30 Nov 1970	144 mm19 Nov 2011	214 mm2011 · driest 0 mm in 2025	74
December	23.4°C4 Dec 2018	-2.6°C30 Dec 1960	85 mm5 Dec 2004	155 mm2014 · driest 0 mm in 2025	74

Typical days per month at NAGASAKI, 1991–2020
Month	Days 25°C+	Days 30°C+	Frost nights	Heavy rain (10 mm+)
January	0	0	1	2
February	0	0	1	3
March	0	0	0	4
April	1	0	0	4
May	10	<1	0	4
June	21	2	0	7
July	29	18	0	6
August	30	24	0	4
September	27	11	0	4
October	12	<1	0	3
November	<1	0	0	3
December	0	0	<1	2

How often, not how much — every day in NAGASAKI’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	<1%	35%	7%	40%	8.6–11.7°C
February	<1%	34%	11%	41%	9.0–13.5°C
March	5%	36%	15%	42%	13.0–16.2°C
April	31%	38%	20%	47%	18.4–20.8°C
May	58%	37%	19%	44%	22.4–24.3°C
June	54%	47%	26%	64%	24.8–27.3°C
July	61%	39%	21%	44%	28.4–31.5°C
August	68%	33%	17%	41%	30.2–32.8°C
September	65%	35%	19%	40%	26.7–29.8°C
October	71%	22%	10%	17%	22.4–25.0°C
November	23%	28%	10%	30%	16.7–20.0°C
December	<1%	31%	7%	35%	11.1–14.5°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.

1951Each stripe is one year’s mean temperature against the 42-year average. Warmest: 2025. Coolest: 1951.2025

The evidence behind this page

Nearby, measured,
and named.

Place identity: GeoNames 1861464
NOAA station: JA000047817 · NAGASAKI
Station distance: 20.5 km from the place centre
Climate period: 1991–2020
Minimum month coverage: 16 usable years
Daylight: Calculated from latitude 32.84°, mid-month, sunrise to sunset including refraction. Not a station measurement.
Sea temperature: NOAA OISST v2.1 1991–2020 monthly climatology, nearest open water 25 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 NAGASAKI is what differs

Nagasaki→Ōmura→Amakusa→Obita→Minamishimabara→Hondomachi-hondo→

Or put two places side by side: Isahaya vs Nagasaki

Best time to visitIsahaya.