🇹🇭Thailand

Thailand (approximately 513,000 km²) occupies the heart of mainland Southeast Asia between 5°–21°N, bordered by the Andaman Sea (865 km coastline) to the southwest and the Gulf of Thailand (1,875 km coastline) to the southeast, encompassing diverse tropical climate zones from monsoonal rainforests to savanna.

The kingdom spans varied topography: the mountainous northern region where peaks exceed 2,500 m and harbor temperate upland valleys; the vast northeastern Khorat Plateau covering one-third of the country with semi-arid climate prone to drought; the fertile Chao Phraya River basin descending through the Central Plains averaging 1–2 m above sea level; and the southern peninsula tapering 1,200 km southward with year-round tropical humidity.

The climate is predominantly Köppen Aw (tropical savanna) and Am (tropical monsoon) with mean annual temperatures ranging from 23°C in northern highlands to 28°C in the southern peninsula. Annual precipitation varies dramatically from under 1,000 mm in the northeastern rain shadow to over 3,500 mm on southern coasts exposed to both southwest and northeast monsoons.

Bangkok (Chao Phraya delta, 2 m) averages 26°C January, 30°C July, 1,500 mm precipitation May–October. Chiang Mai (316 m) records 21°C January, 29°C July, 1,150 mm with March–April smoke episodes from agricultural burning. Udon Thani (1,400 mm) faced drought during the 2015-16 ENSO event, which reduced rice production.

Major impacts include the December 2004 Indian Ocean tsunami, killing over 5,400 people including 2,500 foreigners at Khao Lak and Patong Beach; the July–December 2011 Great Floods inundating 65 of 77 provinces, killing 815, and causing $46.5 billion in damages; and the April 2024 Southeast Asian heatwave reaching 44.2°C in Lampang. Rising sea level (3–5 mm/year) and subsidence (3 cm/year) affect Bangkok's long-term stability.

Our archive covers 1 Thai cities with daily ERA5 reanalysis data going back to 1940. The warmest July averages occur in Bangkok, around 32.5°C, while Bangkok records the coldest January nights near 21.2°C. Comparing the last decade against the 1940–1970 baseline, mean temperatures across these cities have risen by about 1.4°C.2°C, accelerating Bangkok sea-level rise combined with subsidence, the 2015-16 ENSO drought, and recurring Chiang Mai smoke-haze episodes.