Japan recorded extreme temperatures and sudden thunderstorms across the country as Chigasaki celebrated the traditional Hamakoshi festival this week [1, 2].
The intersection of cultural celebration and record-breaking heat highlights the increasing challenge of maintaining traditional outdoor events during volatile summer weather patterns.
In Kōshū City, Yamanashi Prefecture, officials observed a maximum temperature of 39.4 °C in the 勝沼 area [2]. This mark represents the highest temperature recorded in Japan so far this year [2]. The heat was widespread, with more than 200 locations nationwide experiencing extreme heat on the final day of the three-day holiday weekend [2].
Amidst these conditions, the Hamakoshi festival took place on Marine Day, July 21, 2026, at the Nishihama Coast in Chigasaki, Kanagawa Prefecture [1, 4]. The event, which announces the arrival of summer, featured a procession of mikoshi portable shrines [1, 4]. Reports on the number of shrines involved varied, with estimates ranging from 34 to 39 mikoshi [3, 4].
Participants faced intense conditions during the celebrations. "It is hot. It is hot even at 2 o'clock," a festival participant said [1].
The rapid rise in temperature did not only bring heat but also instability to the atmosphere. The extreme heat triggered sudden "guerrilla thunderstorms" in the afternoon across various regions [2]. These localized, intense rain events often follow periods of extreme heat, creating hazardous conditions for outdoor crowds and travelers.
Organizers and participants in Chigasaki continued the tradition of carrying the shrines to the coast despite the temperature spikes [1, 4]. The event remains a central part of the local identity, signaling the seasonal shift for the Kanagawa region [1].
“"It is hot. It is hot even at 2 o'clock."”
The coincidence of a major cultural festival and a national temperature record underscores the growing tension between preserving heritage and ensuring public safety. As 'guerrilla thunderstorms' and extreme heat become more frequent during the Japanese summer, organizers of traditional outdoor events may be forced to implement stricter heat-mitigation strategies or adjust scheduling to avoid peak temperature windows.
