How Much Hotter Has Japan's Summer Gotten? 117 Years on a 3D Map, 1910→2026 | Data in Motion #07
Short answer
- Extremely hot days at the same 61 stations in Japan rose from 1.2 to 10.3 a year.
- A 36-day record stood for 52 years, then rose to 61 days in three years, 2023-2025.
- Just +2.2°F (1.2°C) on average more than doubles days at 95°F (35°C) or more in Kyoto.
Also calledJapan heatwave dayshow many hot days in JapanJapan temperature record95 degree days Japan
Video
Pressing play loads the YouTube player on this page. Watch on YouTube
Explained
In the video
At 61 weather stations across Japan with records back to 1910, we turned each year's extremely hot days - a high of 95°F (35°C) or more - into columns on a 3D map and ran 117 years. For the summer of 2025 we also mapped every day's high temperature at stations nationwide.
Extremely hot days per station per year (average of 61 stations)
| Period | Days a year |
|---|---|
| 1910-1919 | 1.2 |
| 1920s | 1.9 |
| 1930s | 1.9 |
| 1940s | 2.1 |
| 1950s | 1.7 |
| 1960s | 2.1 |
| 1970s | 1.8 |
| 1980s | 1.7 |
| 1990s | 4.2 |
| 2000s | 4.8 |
| 2010s | 7.1 |
| 2020-2025 (6 years) | 12.1 |
| 2016-2025 | 10.3 |
The record among these 61 stations
| Year | Record | Station |
|---|---|---|
| 1942 | 36 days | Kyoto |
| 1994 | 41 days | Kumamoto |
| 2023 | 45 days | Kumagaya |
| 2024 | 54 days | Kyoto |
| 2025 | 61 days | Kyoto |
Kumagaya in 2010 and Kumamoto in 2018 reached exactly 41 days and only tied the record.
Top 3 in selected years
| Year | 1st | 2nd | 3rd |
|---|---|---|---|
| 1942 | Kyoto 36 | Nagoya 31 | Gifu, Fukui 25 |
| 1994 | Kumamoto 41 | Saga 38 | Kyoto 33 |
| 2023 | Kumagaya 45 | Kyoto 43 | Maebashi 36 |
| 2024 | Kyoto 54 | Kumamoto 51 | Okayama, Nagoya, Saga 47 |
| 2025 | Kyoto 61 | Kofu 59 | Kumagaya, Maebashi 53 |
| 2026 (to Oct 22) | Kumamoto 44 | Saga 42 | Fukuoka 38 |
Kyoto vs Kofu, end of summer 2025 (extremely hot days so far)
| Date | Kyoto | Kofu |
|---|---|---|
| Sept 2 | 54 | 55 |
| Sept 3 | 55 | 56 |
| Sept 6 | 56 | 56 |
| Sept 10 | 59 | 58 |
| Sept 16 | 61 | 58 |
| Sept 17 | 61 | 59 |
The two stations were tied for 24 straight days, July 15 to Aug 7. Kofu passed the previous year's record first, on Sept 2.
The heat wave of 2025
- Most stations at 95°F (35°C) or more on one day: 323 stations on July 29
- Highest temperature: 107.2°F (41.8°C) at Isesaki on Aug 5, the highest ever recorded in Japan; 14 stations reached 104°F (40°C) that day
- Counted from daily values at 917 stations nationwide, June to September
Kyoto compared (July-August)
| 1914-1943 | 1996-2025 | |
|---|---|---|
| Average daily high | 89.6°F (32.0°C) | 91.8°F (33.2°C) |
| Days at 95°F+ per year | 7.5 | 21.0 |
| Typical hot-day season | about July 23-Aug 19 | about July 10-Sept 1 |
Making each day of the earlier 30 years just 2.2°F (1.2°C) warmer more than doubles the 95°F+ days, to 16.6 a year.
Nationwide top totals (including automated stations)
| Year | Top |
|---|---|
| 2024 | Dazaifu 62, Hita 57, Fukusaki 56 |
| 2025 | Hita 62, Kyoto 61, Kyotanabe 60 |
| 2026 (to Oct 22) | Hita 53, Dazaifu 49, Kurume 48 |
All 61 stations
Prefectures are Japan's 47 state-like regions. A station is not always in a prefecture's capital: Miyagi's station is Ishinomaki, not the capital Sendai; Shizuoka's is Hamamatsu, not Shizuoka City; Okinawa's is on Ishigaki Island, not in the capital Naha. Nara Prefecture, next to Kyoto and Osaka, has no station with records back to 1910.
Hokkaido (the northernmost main island)
| Station (prefecture) | Most in one year | 2025 | 2026 (to Oct 22) |
|---|---|---|---|
| Abashiri (Hokkaido) | 1999 (3 days) | 0 | 0 |
| Asahikawa (Hokkaido) | 2021 (10 days) | 1 | 0 |
| Nemuro (Hokkaido) | never | 0 | 0 |
| Sapporo (Hokkaido) | 2021, 2023 (3 days) | 2 | 0 |
| Kushiro (Hokkaido) | never | 0 | 0 |
| Obihiro (Hokkaido) | 1924 (9 days) | 6 | 0 |
| Suttsu (Hokkaido) | never | 0 | 0 |
| Hakodate (Hokkaido) | 2023 (1 day) | 0 | 0 |
Tohoku (northern Honshu)
| Station (prefecture) | Most in one year | 2025 | 2026 (to Oct 22) |
|---|---|---|---|
| Aomori (Aomori) | 2023 (9 days) | 2 | 0 |
| Akita (Akita) | 2023 (13 days) | 6 | 1 |
| Miyako (Iwate) | 2023 (6 days) | 4 | 0 |
| Ishinomaki (Miyagi) | 2025 (6 days) | 6 | 1 |
| Yamagata (Yamagata) | 2023 (28 days) | 24 | 6 |
| Fukushima (Fukushima) | 2023 (34 days) | 29 | 9 |
Kanto (the Tokyo region)
| Station (prefecture) | Most in one year | 2025 | 2026 (to Oct 22) |
|---|---|---|---|
| Utsunomiya (Tochigi) | 2025 (29 days) | 29 | 9 |
| Maebashi (Gunma) | 2025 (53 days) | 53 | 18 |
| Mito (Ibaraki) | 2025 (19 days) | 19 | 6 |
| Kumagaya (Saitama) | 2025 (53 days) | 53 | 22 |
| Choshi (Chiba) | 1962, 1978, 2004, 2024 (1 day) | 0 | 0 |
| Tokyo (Tokyo) | 2025 (29 days) | 29 | 12 |
| Yokohama (Kanagawa) | 2024 (22 days) | 14 | 7 |
| Hachijojima (Tokyo, an island 180 mi (290 km) south of the city) | 2024 (1 day) | 0 | 0 |
Chubu (central Honshu)
| Station (prefecture) | Most in one year | 2025 | 2026 (to Oct 22) |
|---|---|---|---|
| Niigata (Niigata) | 2023 (20 days) | 15 | 0 |
| Fushiki (Toyama) | 2025 (24 days) | 24 | 12 |
| Nagano (Nagano) | 2025 (28 days) | 28 | 10 |
| Kanazawa (Ishikawa) | 2023 (20 days) | 9 | 4 |
| Matsumoto (Nagano) | 1994 (22 days) | 18 | 11 |
| Takayama (Gifu) | 2018 (21 days) | 20 | 15 |
| Fukui (Fukui) | 2025 (37 days) | 37 | 22 |
| Kofu (Yamanashi) | 2025 (59 days) | 59 | 26 |
| Tsuruga (Fukui) | 2023 (19 days) | 15 | 13 |
| Iida (Nagano) | 2025 (23 days) | 23 | 15 |
| Gifu (Gifu) | 2025 (51 days) | 51 | 30 |
| Nagoya (Aichi) | 2025 (52 days) | 52 | 29 |
| Hamamatsu (Shizuoka) | 2024 (25 days) | 15 | 15 |
Kinki (the Kyoto–Osaka region)
| Station (prefecture) | Most in one year | 2025 | 2026 (to Oct 22) |
|---|---|---|---|
| Hikone (Shiga) | 2025 (27 days) | 27 | 21 |
| Kyoto (Kyoto) | 2025 (61 days) | 61 | 37 |
| Tsu (Mie) | 2024 (22 days) | 13 | 15 |
| Kobe (Hyogo) | 2024 (19 days) | 10 | 15 |
| Osaka (Osaka) | 2025 (45 days) | 45 | 34 |
| Wakayama (Wakayama) | 2024 (23 days) | 15 | 19 |
Chugoku (western Honshu)
| Station (prefecture) | Most in one year | 2025 | 2026 (to Oct 22) |
|---|---|---|---|
| Sakai (Tottori) | 2025 (26 days) | 26 | 8 |
| Hamada (Shimane) | 1994 (9 days) | 1 | 4 |
| Okayama (Okayama) | 2025 (48 days) | 48 | 36 |
| Hiroshima (Hiroshima) | 2024 (45 days) | 18 | 34 |
| Kure (Hiroshima) | 1951, 1953 (18 days) | 4 | 8 |
| Shimonoseki (Yamaguchi) | 2016 (8 days) | 3 | 5 |
Shikoku (the smallest of the four main islands)
| Station (prefecture) | Most in one year | 2025 | 2026 (to Oct 22) |
|---|---|---|---|
| Tadotsu (Kagawa) | 2024 (34 days) | 24 | 24 |
| Tokushima (Tokushima) | 2026 (28 days) | 12 | 28 |
| Matsuyama (Ehime) | 2024 (33 days) | 11 | 24 |
| Kochi (Kochi) | 2024 (19 days) | 6 | 16 |
Kyushu and Okinawa (the southwest)
| Station (prefecture) | Most in one year | 2025 | 2026 (to Oct 22) |
|---|---|---|---|
| Izuhara (Nagasaki) | 2013, 2018 (5 days) | 0 | 4 |
| Fukuoka (Fukuoka) | 2024 (39 days) | 29 | 38 |
| Saga (Saga) | 2024 (47 days) | 40 | 42 |
| Oita (Oita) | 2024 (33 days) | 15 | 29 |
| Kumamoto (Kumamoto) | 2024 (51 days) | 38 | 44 |
| Nagasaki (Nagasaki) | 2026 (15 days) | 9 | 15 |
| Miyazaki (Miyazaki) | 1998 (27 days) | 7 | 14 |
| Kagoshima (Kagoshima) | 2024 (40 days) | 11 | 16 |
| Naze (Kagoshima, on Amami Oshima island) | 1942, 2024 (13 days) | 0 | 0 |
| Ishigakijima (Okinawa) | 1956 (6 days) | 0 | 1 |
At 44 of the 61 stations, the year with the most extremely hot days in 117 years is 2023 or later. Values for 2026 run to Oct 22.
Notes: On the map, the Amami and Okinawa islands and the Ogasawara islands are moved into inset boxes, as on Japanese weather maps; Minamitorishima is not drawn. Some stations moved site over the years (for example Kyoto in 1913, Tokyo in 2014). Days of 104°F (40°C) or more were given the name kokushobi in April 2026. As a standard, temperature in Japan is measured about 5 ft (1.5 m) above a lawn, shielded from direct sunlight.
This episode in brief
- At the same 61 stations, extremely hot days rose from 1.2 per station per year in the 1910s to 10.3 in 2016-2025, nearly flat through the 1980s and climbing since the 1990s.
- The most extremely hot days in one year among these 61 stations - 36 in Kyoto in 1942 - stood for 52 years, then 41 in Kumamoto stood for 29 years, before rising to 61 (Kyoto, 2025) in three straight record years. Across all stations in Japan the most is 62 days (Dazaifu 2024, Hita 2025).
- In Kyoto in July-August, raising the average high by just 2.2°F (1.2°C) more than doubles the 95°F+ days (7.5 to 16.6 a year); in reality the hot side also spread wider, to 21.0 days (about 2.8 times).
Sources
Where the facts and numbers in the video and on this page come from.
References
- Japan Meteorological Agency, past weather data search (in Japanese)
- Japan Meteorological Agency, changes in extreme events such as heavy rain and extremely hot days (in Japanese)
- Japan Meteorological Agency, all-time national temperature ranking (in Japanese)
- Japan Meteorological Agency, past weather data search (annual, monthly and daily values; retrieved Oct 23, 2026; 2026 values to Oct 22) (in Japanese)
- Japan Meteorological Agency, changes in extreme events (13-station average, 1910-2025) (in Japanese)
- Japan Meteorological Agency press releases (Mar 29, 2007 forecast terminology; Apr 17, 2026 kokushobi) (in Japanese)
- Coastline shapes: Natural Earth
Voice, music, art
- Voice: Irodori-TTS (narrator, Japanese) / Kokoro (narrator, English)
- Music: "Sunrise" and "TALK and WALK" by Kazuchi; "Genki Ippai!" by Kobatto; "Kando wo Anata ni" by Kyaai
