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Warmest sea in Japan in April

373 coastal locations in Japan ranked by their typical April sea temperature. Region-wide average in April: 14.8°C. The top of the list is where to find the warmest swimming this month.

Warmest in April

Yonakuni

25.9°C April mean in Japan

Regional April average

14.8°C

across all 373 coastal locations in Japan

Vs annual mean

-4.3°C

below the year-round regional average

What the Japan sea feels like in April

Water at this temperature is cold and will feel very cold initially, but the body will get used to it and longer swims are possible. Experienced swimmers can manage several hours of swimming, however hypothermia is still a real risk.

Japan monthly average 12.8°C to 26.6°C
J
F
M
A
M
J
J
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S
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N
D
  • Warmest month August 26.6°C
  • Coldest month February 12.8°C
  • Annual mean 19.1°C
  • Months above 20°C 5 of 12

Where April fits in the year

April sits inside the regional pattern shown on the left. Pick a different month to see how the ranking shifts.

All twelve Japan month rankings:

Japan sea temperature map (live)

The map shows today's latest reading at every Japan location. The list below is based on the typical April mean, useful for trip planning weeks or months ahead.

Zoom in to see individual locations. Click a pin for water temperatures. View list →
°C -2 0 1 3 5 7 9 11 13 15 17 19 21 24 27 30 35

Top 50 warmest Japan locations in April

Sorted by the typical April mean built from a decade of daily readings at each location. Click any place for its 30-day chart, monthly profile, and full 10-year history.

# Location April mean
1 Yonakuni 25.9°C
2 Yonakuni Shima Okinawa 25.9°C
3 Kobi Sho Okinawa 25.4°C
4 Funauke Okinawa 25.3°C
5 Ishigaki 25.0°C
6 Minami-Tori Shima Tokyo 24.9°C
7 Miyakojima 24.4°C
8 Hirara Okinawa 24.4°C
9 lo Shima Tokyo 24.4°C
10 Nakano Shima Kagoshima 23.8°C
11 Kanegusuku Okinawa 23.5°C
12 Takara Shima Kagoshima 23.4°C
13 Kerama Kaikyo (Zamami) Okinawa 23.2°C
14 Naha Ko Okinawa 23.1°C
15 Tsuhako Okinawa 23.1°C
16 Haebaru 23.0°C
17 Itoman 23.0°C
18 Okinawa 23.0°C
19 Tomigusuku 23.0°C
20 Minami-Daito Shima Okinawa 22.9°C
21 Chatan 22.9°C
22 Gushikawa 22.9°C
23 Nago 22.8°C
24 Gakiya Okinawa 22.8°C
25 Suku Okinawa 22.8°C
Show 25 more ▸
26 Toguchi Okinawa 22.8°C
27 Kuchi-No-Erabu Shima Kagoshima 22.7°C
28 Haha Shima Tokyo 22.6°C
29 Wadomari Kagoshima 22.6°C
30 Uken Kagoshima 22.6°C
31 Kasari Wan Kagoshima 22.4°C
32 Amami 22.4°C
33 Sanmura Wan Kagoshima 22.4°C
34 Koniya Kagoshima 22.3°C
35 Isso Kagoshima 22.1°C
36 Chichi Shima Tokyo 22.1°C
37 Kumano Kagoshima 22.0°C
38 Fuji 21.8°C
39 Ogasawara 21.7°C
40 Yakushima 21.2°C
41 Hachijo Jima Tokyo 20.8°C
42 Nishinoomote 20.5°C
43 Tori Shima Tokyo 20.2°C
44 Miyazaki Shi 20.1°C
45 Shibushi 20.1°C
46 Makurazaki 20.0°C
47 Miyake Shima Tokyo 20.0°C
48 Aburatsu Miyazaki 19.9°C
49 Uchiumi Miyazaki 19.9°C
50 Kozu Sima Tokyo 19.9°C

Coldest 10 in Japan in April

Same data the other way. Helpful if you want to know which Japan coasts to avoid for swimming in April.

# Location April mean
1 Shibetoro Hokkaido 1.4°C
2 Shana Wan Hokkaido 1.4°C
3 Naibo Wan Hokkaido 1.6°C
4 Hojo 1.6°C
5 Moyoro Wan Hokkaido 1.8°C
6 Furukamappu Wan Hokkaido 1.8°C
7 Hitokappi Wan Hokkaido 1.8°C
8 Koiseboi Hokkaido 2.3°C
9 Abashiri Ko Hokkaido 2.5°C
10 Mombetsu 2.9°C

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