Siem Reap in August is peak Cambodia-monsoon + peak Tonlé Sap floating-village season — 32°C / 90°F afternoons, 25°C / 77°F nights, 18 rain days.
Siem Reap in August runs Khmer heritage-temple-tourism peak-Cambodia-monsoon-and-Tonlé-Sap-peak. DWD data put afternoon highs at 32°C / 90°F and overnight lows at 25°C / 77°F with 18 rain days; humidity sits 80-85% afternoon. Cambodia-monsoon afternoon-thunderstorm pattern hits 14:00-17:00 daily. UV index 11 (extreme) by 11am. Local register: AHA Fair Trade Village, Artisans Angkor, Angkor Silk Farm, Sirivan Couture. Heritage anchors: Angkor Wat (1113), Angkor Thom (1181), Ta Prohm, Banteay Srei (967), Tonlé Sap floating-villages (peak August floating-village register).
Siem Reap August is Angkor Wat sunrise at 5:30 (lily-pond reflection), Tonlé Sap floating-village by 9, Cambodian-cooking class by 14, AHA Fair Trade Village by 16, Cuisine Wat Damnak by 19. Linen + Krama Khmer scarf + Hoka Speedgoat.
Lightweight linen midi or cotton long-sleeve tunic + linen wide-leg pant · Hoka Speedgoat 5 trail shoe · Lack of Color broad-brim sun hat · Krama Khmer scarf · Patagonia Houdini packable shell + Torrentshell 3L · 2L water + LMNT electrolyte + cash USD + insect repellent. Angkor Wat sunrise 5:30am, Tonlé Sap floating-village (Kampong Phluk) 9:00, Cambodian-cooking class 14:00 (or Pub Street lunch if monsoon clears).
Lightweight linen midi + Angkor Silk Farm golden-Khmer scarf · leather sandal or block-heel sandal · lightweight cashmere cardigan for AC · Artisans Angkor jewelry · cash USD + crossbody. AHA Fair Trade Village + Old Market 16:00, Cuisine Wat Damnak fine-dining 19:30, Pub Street Khmer-cuisine + sugar-cane-cocktail 21:30.
Per Deutscher Wetterdienst data: average daily high 32°C (90°F), low 25°C (77°F), 18 rain days. Humidity 80-85% afternoon. Peak Cambodia-monsoon afternoon-thunderstorm pattern hits 14:00-17:00 daily. UV index 11 (extreme) by 11am at the 13.36°N latitude. Daylight 12h 35m. The 7°C / 13°F diurnal swing means morning Angkor Wat sunrise reads 25°C / 77°F at 5:30am + afternoon Pub Street walking reads 32°C / 90°F + evening Pub Street + Old French Quarter reads 27-29°C / 81-84°F by 21:00.
Yes — August reads peak floating-village season at Tonlé Sap (the recognized 'monsoon-flooded-forest' register at peak). The heritage Tonlé Sap floating-villages (Kampong Phluk + Chong Kneas, 30 km / 18 mile southeast of Siem Reap — Cambodia largest freshwater lake): Kampong Phluk is the recognized 'authentic Tonlé Sap' floating-village (less-touristic than Chong Kneas), the heritage stilt-house architecture + the recognized monsoon-flooded mangrove-forest boat-tour register. Cost: $20-40 per person via the heritage Tonlé Sap Boat Tour operators (Sam Veasna Center, Tara Boat). Schedule: depart Siem Reap 6:30am, return 14:00 (the 'morning-light + bird-watching' register before 14:00 monsoon). Pack: lightweight linen + Hoka Speedgoat + Lack of Color broad-brim hat + Patagonia Houdini packable shell + 2L water + mineral SPF 50 + LMNT electrolyte + cash USD + insect repellent + Krama Khmer scarf. Skip Chong Kneas village absolutely (the heritage tourist-trap-orphanage scam register since 2010).
The Angkor Wat sunrise ('lily-pond reflection' photographic register) requires: (1) Angkor Pass (Sokimex Concession 1-day $37 / 3-day $62 / 7-day $72 — Apsara Authority Ticket Office on Charles de Gaulle Avenue, 5:00am opening). (2) Tuk-tuk hire ($15-25 per-day for 4:30am sunrise pickup). (3) Arrive at Angkor Wat west-causeway entrance by 5:00am. (4) Sunrise reads 5:30-6:00am August. (5) Post-sunrise (6:00-9:00am): Angkor Wat interior + central-tower climb. August-specific: monsoon-cloud-cover risk reads 40-50% — verify NWS-Cambodia or weather.com day-of for clear-sunrise probability. Pack: lightweight linen midi or sleeveless-base + cotton tunic + Krama Khmer scarf + Hoka Speedgoat trail shoe + Lack of Color broad-brim hat + Patagonia Houdini packable shell + 2L water + LMNT electrolyte + cash USD + Angkor Pass + insect repellent.
The APSARA Authority (Apsara National Authority — Cambodian government agency managing Angkor Archaeological Park since 1995) dress code (2017 formal enforcement): knee-and-shoulder cover required at all temple zones absolutely. Non-compliant items: shorts above-the-knee, sleeveless tops, tank tops, mini-skirts, see-through fabrics, swimwear-style tops. APSARA security turns away non-compliant visitors at every temple gate. The 'sleeveless-base + cotton-tunic-cover' Angkor-strategy is the most-flexible register. Pack: lightweight linen midi dress with knee-and-shoulder cover OR sleeveless-base + cotton long-sleeve tunic + Krama Khmer scarf for cover. Buy a Krama at AHA Fair Trade Village ($5-25).
The heritage Cuisine Wat Damnak (Joannès Rivière's contemporary Cambodian fine-dining — 'Asia's 50 Best Restaurants' Siem Reap-anchor); the heritage Embassy Restaurant (Pol Kompheak's Khmer fine-dining); the heritage Marum (Friends-International social-enterprise contemporary Khmer); the heritage Touch Restaurant + Bar (Pub Street Khmer fine-dining); the heritage Genevieve's (Pub Street Khmer + international fusion); the heritage Sister Srey Cafe (Sivutha Boulevard social-enterprise café); the heritage The Hashi Restaurant (Sivutha Boulevard Japanese-Khmer fusion); the heritage Park Hyatt Siem Reap Glasshouse; the heritage The Sugar Palm (Sok San Road Cambodian-home-cooking); the heritage Belmond La Résidence d'Angkor afternoon-tea + spa; the heritage Charlie's Underground (Pub Street expatriate-bar); the heritage Mahob Khmer (Pub Street chef Sothea Khmer-fine-dining alternative); the heritage Cooking Class with Mahob (the recognized 'Khmer cooking class' destination — half-day $40-60 per person, market-tour + cooking + lunch). Pack: lightweight linen midi + Angkor Silk Farm golden-Khmer scarf + leather sandal + lightweight cashmere cardigan for AC + crossbody for evening; cotton long-sleeve tunic + linen wide-leg + Hoka Speedgoat + Lack of Color broad-brim hat + Krama Khmer scarf for daytime Angkor temple-touring.