Spring (March to May) brings cherry blossoms to Peace Memorial Park and Hiroshima Castle along with comfortable, mild weather, while autumn (October to November) offers cool, clear days and good visibility for the ferry crossing to Miyajima. Summer (June to August) is hot, humid and prone to typhoons from late August into early October, and winter is cool and dry with occasional cold snaps.
Japan is seismically active and minor tremors happen from time to time across the country. Note your accommodation's exits on arrival and follow any staff instructions during a quake; a short visit needs no special preparation beyond basic awareness.
Typhoons and heavy rain mainly affect the region from June through early October, occasionally causing flooding, landslides in hillside areas, or disrupted ferries and trains. Check the forecast if travelling in this window, and avoid unnecessary trips outdoors during heavy rain warnings.
Summer afternoons regularly bring high heat and humidity, raising the risk of heat exhaustion, particularly while walking around the open Peace Memorial Park. Carry water, seek shade or air-conditioned spaces through the middle of the day, and pace outdoor sightseeing accordingly.