Japan · 1991–2020

Best time to visit
Koga.

May leads for comfortable weather in Koga: typically 25°C by day, 13.6°C at night, with 109 mm of rain. Based on measured 1991–2020 NOAA station history.

Best comfortMay

Typical high25°C

Typical low13.6°C

Rain in May109 mm

Comfort

May

May · October · April

78climate match

Beach

August

August · July · June

56climate match

Outdoors

April

April · November · March

79climate match

The weakest month is January, scoring 24 against May’s 78 — days reach only 9.9°C, 14° below the 24°C the score treats as ideal, and nights drop to -1.1°C.

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

249.9° / -1.1°

Feb

2810.9° / -0.3°

Mar

3914.5° / 2.9°

Apr

6120.1° / 8.2°

May

7825° / 13.6°

Jun

5427.4° / 18°

Jul

3531.1° / 22.1°

Aug

3532.5° / 23.1°

Sep

4328.1° / 19.4°

Oct

6322.4° / 13.1°

Nov

5617° / 6.5°

Dec

3412.1° / 1.2°

Monthly climate evidence for Koga — daylight is calculated from latitude, everything else is measured
Month	Day	Night	Rain	Wet days	Daylight	Comfort	Coverage
January	9.9°C	-1.1°C	26 mm	2.3	9 h 57	24	Good coverage
February	10.9°C	-0.3°C	35 mm	4.8	10 h 49	28	Good coverage
March	14.5°C	2.9°C	67 mm	7.2	11 h 51	39	Good coverage
April	20.1°C	8.2°C	98 mm	9	13 h 04	61	Good coverage
May	25°C	13.6°C	109 mm	9.2	14 h 04	78	Good coverage
June	27.4°C	18°C	179 mm	13.5	14 h 36	54	Good coverage
July	31.1°C	22.1°C	168 mm	14.1	14 h 24	35	Good coverage
August	32.5°C	23.1°C	154 mm	9.4	13 h 32	35	Good coverage
September	28.1°C	19.4°C	224 mm	13.3	12 h 22	43	Good coverage
October	22.4°C	13.1°C	195 mm	9.8	11 h 12	63	Good coverage
November	17°C	6.5°C	62 mm	5.5	10 h 12	56	Good coverage
December	12.1°C	1.2°C	41 mm	4	9 h 42	34	Good coverage

What has changed

Koga runs +1.9°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

+1.2

Feb

+1.5

Mar

+2.9

Apr

+1.9

May

+2.2

Jun

+2.5

Jul

+2.7

Aug

+2.0

Sep

+2.0

Oct

+1.7

Nov

+1.3

Dec

+0.9

May daytime highs, 2011–2025. Last recorded: 23.7°C.

Records at KUMAGAYA, 1951–2026
Month	Record high	Record low	Wettest day	Wettest / driest month	Years
January	23.0°C27 Jan 1969	-10.5°C27 Jan 1954	82 mm31 Jan 2009	109 mm2009 · driest 0 mm in 1976	73
February	27.0°C11 Feb 1962	-7.3°C9 Feb 1984	119 mm15 Feb 2014	189 mm2014 · driest 0 mm in 2026	73
March	26.9°C30 Mar 1998	-7.7°C6 Mar 1977	63 mm1 Mar 1951	150 mm1951 · driest 3 mm in 1993	74
April	30.9°C28 Apr 2015	-2.2°C3 Apr 1963	77 mm18 Apr 2020	187 mm2008 · driest 0 mm in 2025	74
May	36.2°C27 May 2019	1.2°C3 May 1953	104 mm3 May 2012	282 mm1965 · driest 0 mm in 2025	73
June	39.8°C24 Jun 2011	9.1°C4 Jun 1957	267 mm28 Jun 1966	497 mm1966 · driest 0 mm in 2025	73
July	41.1°C23 Jul 2018	11.8°C2 Jul 1976	172 mm20 Jul 2011	343 mm2022 · driest 0 mm in 2025	74
August	40.9°C16 Aug 2007	13.9°C20 Aug 1956	212 mm31 Aug 1971	419 mm2016 · driest 0 mm in 2025	72
September	39.7°C2 Sep 2000	8.6°C29 Sep 1960	302 mm12 Sep 1982	565 mm1958 · driest 0 mm in 2025	72
October	33.8°C1 Oct 2018	2.6°C29 Oct 1971	223 mm12 Oct 2019	513 mm2004 · driest 0 mm in 2025	73
November	26.7°C2 Nov 2023	-3.2°C23 Nov 1966	69 mm20 Nov 1970	170 mm1975 · driest 0 mm in 2025	73
December	26.3°C5 Dec 2004	-7.8°C31 Dec 1967	149 mm27 Dec 2006	163 mm2006 · driest 0 mm in 1973	73

Typical days per month at KUMAGAYA, 1991–2020
Month	Days 25°C+	Days 30°C+	Frost nights	Heavy rain (10 mm+)
January	0	0	12	1
February	0	0	10	<1
March	<1	0	3	2
April	4	<1	<1	3
May	16	3	0	3
June	21	7	0	4
July	25	18	0	4
August	28	23	0	4
September	21	10	0	5
October	6	<1	0	4
November	<1	0	<1	1
December	0	0	6	<1

The best month has moved. On the 1961–1990 numbers the strongest month here was May (scoring 84); on 2011–2025 it is October (85). Both are scored the same way, from the same station — only the climate underneath changed.

How often, not how much — every day in KUMAGAYA’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%	10%	4%	5%	8.2–10.9°C
February	1%	18%	4%	15%	8.6–12.3°C
March	6%	25%	8%	23%	12.0–15.7°C
April	37%	30%	11%	33%	17.8–21.3°C
May	62%	33%	13%	40%	22.3–25.9°C
June	56%	44%	18%	61%	24.2–28.5°C
July	58%	42%	14%	50%	27.3–33.1°C
August	68%	33%	15%	41%	29.9–34.7°C
September	58%	43%	19%	57%	24.9–29.5°C
October	51%	33%	15%	31%	20.4–23.2°C
November	16%	18%	6%	13%	15.3–18.3°C
December	<1%	11%	3%	4%	10.6–13.3°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 48-year average. Warmest: 2025. Coolest: 1976.2025

The evidence behind this page

Nearby, measured,
and named.

Place identity: GeoNames 1859093
NOAA station: JA000047626 · KUMAGAYA
Station distance: 30.2 km from the place centre
Climate period: 1991–2020
Minimum month coverage: 16 usable years
Daylight: Calculated from latitude 36.18°, 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 KUMAGAYA is what differs

Kawagoe→Ageo→Ōta→Kumagaya→Sayama→Kukichūō→

Or put two places side by side: Koga vs Kawagoe

Best time to visitKoga.

May

August

April

The whole year,without the guesswork.

Koga runs +1.9°Con the 1961–1990 baseline.

Nearby, measured,and named.

Best time to visit
Koga.

The whole year,
without the guesswork.

Koga runs +1.9°C
on the 1961–1990 baseline.

Nearby, measured,
and named.