Siem Reap in June is peak Cambodia-monsoon — 34°C / 93°F afternoons, 25°C / 77°F nights, 18 rain days from afternoon thunderstorms.
Siem Reap in June runs Khmer heritage-temple-tourism peak-Cambodia-monsoon. DWD data put afternoon highs at 34°C / 93°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 June-October. UV index 12 (extreme-plus) by 11am. Local register: AHA Fair Trade Village, Artisans Angkor, Angkor Silk Farm (Pucy Tuck silk-village 16 km west), Sirivan Couture. Heritage anchors: Angkor Wat (1113), Angkor Thom (1181 Jayavarman VII walled-city + Bayon 216-face-towers temple), Ta Prohm (Tomb-Raider 1999 jungle-tree-and-stone), Banteay Srei (967 'Citadel of Women' 30 km northeast), Tonlé Sap floating-villages (30 km southeast).
Siem Reap June is Angkor Wat sunrise at 5:30 (lily-pond reflection), Bayon by 8, Ta Prohm by 10, AHA Fair Trade Village by 13 (avoid 14-17 monsoon), Cuisine Wat Damnak by 19. Linen + Krama Khmer scarf + Hoka Speedgoat + Angkor Silk Farm.
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, Bayon 8:00, Ta Prohm 10:00, AHA Fair Trade Village 13:00 (avoid 14-17 monsoon).
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. Cuisine Wat Damnak fine-dining 19:30, Pub Street Khmer-cuisine + sugar-cane-cocktail 21:30.
Per Deutscher Wetterdienst data: average daily high 34°C (93°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 June-October. UV index 12 (extreme-plus) by 11am at the 13.36°N latitude. Daylight 13h 5m (peak summer solstice). The 9°C / 16°F diurnal swing means morning Angkor Wat sunrise reads 25°C / 77°F at 5:30am + afternoon Pub Street walking reads 34°C / 93°F + evening Pub Street + Old French Quarter reads 27-29°C / 81-84°F by 21:00.
The heritage Angkor Wat sunrise (the 'lily-pond reflection' photographic register) requires: (1) The heritage Angkor Pass (Sokimex Concession 1-day $37 / 3-day $62 / 7-day $72 ticket — purchase at 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 for 5:30-6:00am lily-pond reflection register. (4) Sunrise reads 5:30-6:00am June. (5) Post-sunrise (6:00-9:00am): Angkor Wat interior + central-tower climb (70-degree stair register). 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 heritage APSARA Authority (the recognized Apsara National Authority — Cambodian government agency managing Angkor Archaeological Park since 1995) dress code (2017 formal enforcement): knee-and-shoulder cover required at Angkor Wat + Angkor Thom + Ta Prohm + Banteay Srei + 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 checks at every temple gate + turns away non-compliant visitors. 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).
Both are recognized Siem Reap heritage day-trip destinations. Banteay Srei (the heritage 967 'Citadel of Women' rose-pink-sandstone miniature temple, 30 km northeast — the recognized 'jewel of Khmer architecture' register, the heritage 1923 André Malraux art-theft historical incident): typical half-day combine with Banteay Samre + Pre Rup temple cluster on the 'Grand Circuit' tour. Cost: included in Angkor Pass + tuk-tuk hire ($25-40). Tonlé Sap floating-villages (Kampong Phluk + Chong Kneas, 30 km southeast — Cambodia largest freshwater lake, the 'monsoon-flooded-forest' register): June reads early-monsoon-rising-lake — the heritage 'floating-village' visual impact begins ramping up. Better than May for the 'floating' aesthetic, peaks August-October. Pack: lightweight linen + Krama Khmer scarf + Hoka Speedgoat + broad-brim hat + 2L water + mineral SPF 50 + cash USD + Angkor Pass + insect repellent.
The heritage Cuisine Wat Damnak (Joannès Rivière's heritage 2011 contemporary Cambodian fine-dining — recognized '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 (2002 Park Hyatt afternoon-tea + Glasshouse fine-dining); 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 register). 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.