The warmest sea we measure is near Naha (Okinawa), averaging 28.9 °C in August; the coolest, near Helsinki (Finland), drops to 0.7 °C in March. Cherry blossom opens first in Okinawa (16 January) and last in Hokkaido (1 May); maples turn red from 28 October in Hokkaido to 15 December in Kagoshima.
Two charts for timing a trip around nature: how warm the sea is in each month, and when cherry blossom and autumn leaves arrive across Japan. Both use the averages printed on our sea temperature, cherry blossom and autumn leaves pages. Use Save as image or Copy link under each chart to share it. More charts: lean seasons, daylight and weather, the best-month finder and how places stack up.
How warm is the sea, month by month?
Average sea surface temperature, 1991–2020, at the nearest open-sea point within 30 km of each place's weather station. Rows run from the warmest peak to the coolest.1
- under 13 °C
- 13 to 16 °C
- 16 to 19 °C
- 19 to 22 °C
- 22 to 25 °C
- 25 °C or more
Table: Europe, sea temperature by month (°C)
| Place | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Nicosia (Cyprus) | 17.1 | 16.6 | 16.9 | 18.0 | 20.8 | 24.3 | 27.3 | 28.4 | 27.4 | 25.3 | 22.0 | 18.9 |
| Rome (Italy) | 14.8 | 14.1 | 14.1 | 15.4 | 18.4 | 21.9 | 24.6 | 25.6 | 23.7 | 21.4 | 18.8 | 16.3 |
| Amsterdam (Netherlands) | 6.2 | 5.5 | 6.2 | 8.4 | 11.6 | 14.7 | 17.3 | 18.7 | 17.5 | 14.8 | 11.3 | 8.2 |
| Riga (Latvia) | 2.3 | 0.9 | 1.0 | 3.4 | 8.6 | 13.8 | 17.9 | 18.7 | 15.6 | 11.3 | 7.6 | 4.8 |
| Tallinn (Estonia) | 2.3 | 1.0 | 0.9 | 2.4 | 6.4 | 11.6 | 16.4 | 17.4 | 14.7 | 10.7 | 7.3 | 4.5 |
| Helsinki (Finland) | 2.1 | 0.8 | 0.7 | 2.2 | 6.2 | 11.4 | 16.1 | 17.2 | 14.4 | 10.3 | 7.0 | 4.2 |
| Dublin (Ireland) | 9.1 | 8.1 | 7.9 | 8.7 | 10.6 | 13.1 | 14.7 | 15.1 | 14.5 | 13.4 | 12.1 | 10.6 |
| Reykjavik (Iceland) | 5.3 | 5.1 | 4.9 | 5.6 | 7.2 | 9.6 | 11.2 | 11.4 | 10.0 | 8.3 | 6.8 | 5.8 |
Table: Japan, sea temperature by month (°C)
| Place | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Naha (Okinawa) | 22.6 | 21.7 | 21.8 | 22.8 | 24.7 | 26.8 | 28.7 | 28.9 | 28.3 | 27.1 | 25.4 | 23.9 |
| Kagoshima (Kagoshima) | 18.8 | 17.8 | 18.3 | 19.5 | 21.4 | 23.7 | 26.5 | 28.2 | 27.4 | 25.3 | 22.8 | 20.6 |
| Miyazaki (Miyazaki) | 19.6 | 18.6 | 18.8 | 20.1 | 21.9 | 23.9 | 26.3 | 27.9 | 27.3 | 25.5 | 23.5 | 21.3 |
| Kochi (Kochi) | 18.1 | 17.1 | 17.4 | 18.5 | 20.8 | 23.4 | 26.1 | 27.7 | 27.0 | 25.1 | 22.7 | 20.0 |
| Nagasaki (Nagasaki) | 16.7 | 15.6 | 16.0 | 17.4 | 19.6 | 22.3 | 25.4 | 27.6 | 26.6 | 24.1 | 21.4 | 18.7 |
| Kumamoto (Kumamoto) | 14.4 | 13.3 | 14.1 | 16.2 | 18.9 | 22.0 | 25.4 | 27.4 | 26.2 | 23.1 | 19.7 | 16.7 |
| Tsu (Mie) | 14.3 | 13.5 | 13.7 | 15.4 | 18.5 | 21.8 | 25.4 | 27.4 | 25.7 | 22.5 | 19.6 | 16.7 |
| Saga (Saga) | 14.3 | 13.2 | 14.0 | 16.1 | 18.9 | 22.0 | 25.4 | 27.3 | 26.1 | 23.0 | 19.6 | 16.6 |
| Toyama (Toyama) | 12.9 | 10.7 | 10.0 | 11.3 | 15.2 | 19.9 | 23.8 | 26.9 | 25.4 | 21.9 | 18.7 | 15.6 |
| Fukui (Fukui) | 13.3 | 11.5 | 11.0 | 12.7 | 16.1 | 20.1 | 23.9 | 26.8 | 25.3 | 22.0 | 19.0 | 15.9 |
| Kanazawa (Ishikawa) | 13.0 | 11.0 | 10.5 | 12.1 | 15.8 | 19.9 | 23.7 | 26.8 | 25.2 | 21.9 | 18.8 | 15.7 |
| Kobe (Hyogo) | 14.4 | 13.1 | 13.5 | 15.2 | 17.8 | 21.2 | 24.7 | 26.8 | 25.9 | 23.1 | 19.6 | 16.7 |
| Osaka (Osaka) | 14.3 | 13.0 | 13.3 | 15.1 | 17.8 | 21.2 | 24.7 | 26.8 | 25.8 | 22.9 | 19.5 | 16.6 |
| Tokushima (Tokushima) | 15.0 | 13.7 | 14.0 | 15.5 | 17.9 | 21.3 | 24.6 | 26.8 | 26.1 | 23.6 | 20.3 | 17.3 |
| Tottori (Tottori) | 13.7 | 12.0 | 12.1 | 13.7 | 16.6 | 20.4 | 24.0 | 26.8 | 25.3 | 22.1 | 19.2 | 16.3 |
| Wakayama (Wakayama) | 15.6 | 14.4 | 14.6 | 16.2 | 18.5 | 21.6 | 24.8 | 26.8 | 26.0 | 23.6 | 20.7 | 17.9 |
| Fukuoka (Fukuoka) | 15.5 | 14.0 | 14.1 | 15.4 | 17.9 | 20.7 | 24.4 | 26.7 | 25.3 | 22.7 | 20.4 | 17.9 |
| Matsue (Shimane) | 14.2 | 12.7 | 12.8 | 14.2 | 16.9 | 20.5 | 23.9 | 26.7 | 25.3 | 22.4 | 19.7 | 16.7 |
| Shizuoka (Shizuoka) | 16.1 | 15.2 | 15.5 | 16.9 | 19.1 | 21.6 | 24.4 | 26.5 | 25.7 | 23.3 | 20.9 | 18.3 |
| Niigata (Niigata) | 12.3 | 10.4 | 9.7 | 10.9 | 14.5 | 19.3 | 23.1 | 26.3 | 25.1 | 21.6 | 18.2 | 15.1 |
| Oita (Oita) | 15.5 | 14.1 | 14.3 | 15.6 | 18.0 | 21.1 | 24.2 | 26.2 | 25.0 | 22.8 | 20.4 | 17.8 |
| Matsuyama (Ehime) | 14.8 | 13.2 | 13.4 | 14.8 | 17.2 | 20.5 | 24.2 | 26.1 | 25.1 | 22.9 | 20.2 | 17.3 |
| Chiba (Chiba) | 13.6 | 12.5 | 13.2 | 15.0 | 17.9 | 20.9 | 23.4 | 25.9 | 24.7 | 21.6 | 18.9 | 16.0 |
| Tokyo (Tokyo) | 13.6 | 12.5 | 13.2 | 15.0 | 17.9 | 20.9 | 23.4 | 25.9 | 24.7 | 21.6 | 18.9 | 16.0 |
| Yokohama (Kanagawa) | 14.5 | 13.4 | 13.9 | 15.5 | 18.2 | 21.0 | 23.5 | 25.8 | 24.8 | 22.0 | 19.5 | 16.7 |
| Akita (Akita) | 11.3 | 9.4 | 8.8 | 10.0 | 13.6 | 18.5 | 22.3 | 25.5 | 24.4 | 20.9 | 17.4 | 14.1 |
| Mito (Ibaraki) | 14.6 | 13.0 | 13.1 | 14.5 | 16.9 | 19.4 | 21.7 | 24.1 | 23.3 | 20.8 | 18.8 | 16.4 |
| Sendai (Miyagi) | 11.2 | 9.1 | 8.6 | 10.3 | 13.5 | 17.7 | 21.1 | 23.7 | 22.6 | 19.4 | 16.5 | 13.8 |
| Aomori (Aomori) | 10.2 | 8.2 | 7.6 | 7.9 | 10.8 | 15.2 | 19.1 | 22.6 | 22.3 | 19.1 | 15.2 | 12.3 |
This is the temperature of the sea surface offshore, not of the water at a particular beach, and it says nothing about safety. Places without open sea within 30 km of their weather station are not shown; the sea temperature page lists them.
When do cherry blossom and autumn leaves arrive in Japan?
Each row is a prefecture's weather station: the pink dot is the average date cherry blossom opens, the hollow dot full bloom, and the amber diamond the date maple leaves turn red, all 1991–2020 averages from the Japan Meteorological Agency. Rows run from the earliest blossom to the latest.2
- Cherry blossom opens
- Full bloom
- Maple leaves turn red
Table: blossom and maple dates by prefecture
| Prefecture | Blossom opens | Full bloom | Maple leaves turn red |
|---|---|---|---|
| Okinawa | 16 January | 4 February | – |
| Fukuoka | 22 March | 31 March | 1 December |
| Kochi | 22 March | 30 March | 2 December |
| Kumamoto | 22 March | 1 April | 2 December |
| Miyazaki | 23 March | 2 April | 4 December |
| Nagasaki | 23 March | 2 April | 7 December |
| Aichi | 24 March | 2 April | 28 November |
| Ehime | 24 March | 3 April | 5 December |
| Oita | 24 March | 4 April | 28 November |
| Saga | 24 March | 2 April | 30 November |
| Shizuoka | 24 March | 2 April | 5 December |
| Tokyo | 24 March | 31 March | 28 November |
| Wakayama | 24 March | 3 April | 6 December |
| Gifu | 25 March | 2 April | 26 November |
| Hiroshima | 25 March | 3 April | 22 November |
| Kanagawa | 25 March | 1 April | 14 December |
| Yamanashi | 25 March | 2 April | 29 November |
| Kagoshima | 26 March | 5 April | 15 December |
| Kyoto | 26 March | 4 April | 5 December |
| Yamaguchi | 26 March | 4 April | 6 December |
| Hyogo | 27 March | 5 April | 1 December |
| Kagawa | 27 March | 4 April | 23 November |
| Osaka | 27 March | 4 April | 1 December |
| Saitama | 27 March | 3 April | 1 December |
| Nara | 28 March | 4 April | 21 November |
| Okayama | 28 March | 4 April | 29 November |
| Tokushima | 28 March | 4 April | 28 November |
| Gunma | 29 March | 5 April | 8 December |
| Mie | 29 March | 3 April | 25 November |
| Shimane | 29 March | 5 April | 24 November |
| Tottori | 29 March | 5 April | 30 November |
| Chiba | 30 March | 6 April | 12 December |
| Ibaraki | 30 March | 6 April | 20 November |
| Tochigi | 30 March | 6 April | 20 November |
| Fukui | 1 April | 7 April | 28 November |
| Shiga | 1 April | 8 April | 28 November |
| Ishikawa | 3 April | 8 April | 24 November |
| Toyama | 3 April | 8 April | 24 November |
| Fukushima | 7 April | 11 April | 17 November |
| Miyagi | 8 April | 13 April | 21 November |
| Niigata | 8 April | 13 April | 15 November |
| Nagano | 11 April | 16 April | 12 November |
| Yamagata | 13 April | 18 April | 25 November |
| Akita | 17 April | 22 April | 12 November |
| Iwate | 18 April | 24 April | 13 November |
| Aomori | 22 April | 26 April | 13 November |
| Hokkaido | 1 May | 6 May | 28 October |
Stations, species and substitute observations differ between prefectures; the cherry blossom and autumn leaves pages give each one, with the earliest and latest openings on record. Dates in any one year can be weeks away from these averages.
Key takeaways
- Warmest sea: near Naha (Okinawa), 28.9 °C in August on average.
- First blossom: Okinawa, around 16 January. Last: Hokkaido, around 1 May.
- Maples turn red from 28 October (Hokkaido) to 15 December (Kagoshima).
- What we would skip: planning around one date. These are 30-year averages; check the forecast for your year.
Sources
The charts show the averages printed on the linked sea temperature, cherry blossom and autumn leaves pages. See how we research.
- Sea temperature: NOAA Optimum Interpolation Sea Surface Temperature (OISST) v2.1, 0.25° grid, monthly long-term mean 1991–2020 (file sst.mon.ltm.1991-2020.nc). Data provided by the NOAA/OAR/PSL, Boulder, Colorado, USA, from their Web site at https://psl.noaa.gov/. Huang, B., C. Liu, V. Banzon, E. Freeman, G. Graham, B. Hankins, T. Smith and H.-M. Zhang (2021), Improvements of the Daily Optimum Interpolation Sea Surface Temperature (DOISST) Version 2.1, Journal of Climate 34, 2923–2939, doi:10.1175/JCLI-D-20-0166.1. Dataset page. Accessed 24 September 2026. Public domain (NOAA PSL disclaimer). The choice of grid cell and the rounding are ours; these are not official NOAA figures, and NOAA does not endorse this site.
- Cherry blossom and autumn leaves: 出典：気象庁ホームページ（生物季節観測の情報）: さくらの開花日・満開日 and 生物季節観測累年値ファイル (さくらの開花, さくらの満開, かえでの紅葉), 平年値 1991–2020. Japan Meteorological Agency. Accessed 22 September 2026. Licensed under PDL1.0. 「生物季節観測の情報」（気象庁）を加工して作成 — edited by Gallivanting Gadabout (English wording, date format and selection).
Colour bands and the timeline layout are ours. Dates are placed on a 2026 calendar only to draw them.