Thailand has two monsoons, one tax, two power utilities and seven places we plan around

Seven places in one table

Source: Thai Meteorological Department climate normals 1991-2020, published as WMO sheets; Krabi has no 1991-2020 sheet of its own, so its row uses the Ko Lanta station in Krabi Province. Each place has its own page: Phuket, Koh Samui, Bangkok, Chiang Mai, Hua Hin, Pattaya and Krabi.

Which coast rains when

The south-west monsoon brings the rainy season from about mid-May to mid-October; the north-east monsoon runs from about mid-October to mid-February and brings its heaviest rain to the Gulf side of the south. On the Andaman coast (Phuket, Krabi) rainfall peaks in September; on the Gulf side (Koh Samui) it peaks in November to January (Thai Meteorological Department, as summarised in Wikipedia's Geography of Thailand). Hua Hin, in the Gulf's rain shadow, is the driest of the seven; Chiang Mai has a true cool, dry season from November to February.

Where the power comes from, and what to ask

Most of the country is supplied by the Provincial Electricity Authority (PEA, 74 provinces); Bangkok, Nonthaburi and Samut Prakan by the Metropolitan Electricity Authority. Mains supply is typically 220⁠-⁠230 V single-phase or 380⁠-⁠400 V three-phase, at 50 Hz. PEA offers direct-connected single-phase meters of 5(15), 15(45) and 30(100) A and three-phase meters of 15(45) and 30(100) A, with larger loads on CT-metered service, and a new or upgraded connection is applied for at PEA with an inspection fee. Heaters from about 8 kW and chillers of 4 HP usually mean asking the utility for more capacity or for three-phase. The power note covers the questions.

Tax and import: what is verified

• VAT. Thailand's statutory rate is 10 percent; the reduced 7 percent rate has been extended to 30 September 2027 under Royal Decree No. 807 B.E. 2569 and applies to imports too (KPMG, PwC and Forvis Mazars summaries). Our ranges are before VAT, shown as its own line in a quote.
• Import duty. The duty depends on the customs classification and the country of origin. The likely tariff headings for a heater, a prefabricated cabin, a chiller and tempered glass, all to be confirmed by Thai Customs, are set out in the import note. We state no duty percentage, because we could not verify one.
• Origin. Preferential rates under agreements such as ATIGA, ACFTA, RCEP, AJCEP and the Australian and New Zealand agreements need an origin certificate; there is no EU-Thailand or Finland-Thailand agreement in force (European Commission).

The reasoning, and what a quote should show line by line, is in import duty or local assembly.

Permits, licences and committees: the rules we can name

• Building permits. Under the Building Control Act B.E. 2522, constructing, modifying or moving a building generally needs a permit from the local officer (a municipal mayor, a tambon administrative organisation's executive chair, the Bangkok Governor or Pattaya's mayor, depending on the area); some alterations go by notification (Tilleke & Gibbins, 2025). Whether a cabin, pool or plant niche counts is for your local office.
• Condominiums. Under the Condominium Act B.E. 2522, construction that changes or adds to common property needs the approval of the general meeting of co-owners, with a quorum of one-quarter of the votes (Tilleke & Gibbins). Your building's regulations add the detail.
• Hotels and spas. Hotels need a licence under the Hotel Act B.E. 2547; spa and health-massage businesses are licensed under the Health Establishment Act B.E. 2559 by the Department of Health Service Support. We found no pool-specific water-quality standard and could not confirm whether a hotel sauna or plunge pool counts as a spa; ask your provincial public-health office.

These are summaries for orientation, not legal advice. We bring drawings, loads and materials to those conversations and do not state any exemption or threshold we have not verified.

The national numbers, with sources

• 32.97 million international arrivals in 2025 and 35.55 million in 2024; January to September 2026 down 3.8 percent on a year earlier (Ministry of Tourism and Sports; preliminary).
• Wellness economy US$ 42.7 billion in 2024; wellness tourism spending up 36.4 percent to US$ 14 billion, 15th in the world (Global Wellness Institute, 2026).

The arrivals dip is a reason to keep a build modest and phased, not a forecast; see hospitality and clubs for how operators stage the spend.

Outside the seven places

We take projects elsewhere in Thailand on request. Send a pin on WhatsApp with the plan and we reply with the access questions, the calendar for that coast and a layout. The same equipment, the same sizing and the same payment terms apply; freight and the delivery leg are itemised in the quote.