Verdict: Fair month
Chiang Mai Weather in September
September runs warm in Chiang Mai, with daily highs around 30°C (86°F) and nights near 23°C (73°F). It's also the wet side of the calendar: rain falls on about 26 days, so build flexibility into plans. September is workable in Chiang Mai if your dates are fixed — just plan around the conditions.
Average high
30°C / 86°F
Average low
23°C / 73°F
Rain days
~26
Precipitation
416 mm
What to pack for Chiang Mai in September
- Light, breathable clothing — linen and technical fabrics earn their keep
- High-SPF sunscreen, sunglasses, and a refillable water bottle
- Rain gear is non-negotiable — expect rain on roughly 26 days
- Quick-dry shoes — downpours are short but heavy
- Comfortable walking shoes — every guide on this site assumes you'll use them
September against the rest of the year
Warmest in Chiang Mai: Apr (36°C / 97°F) · Coolest: Jan (28°C / 82°F) · Wettest: Aug (~30 rain days)
28°
17°
Jan
30°
18°
Feb
35°
21°
Mar
36°
24°
Apr
34°
24°
May
32°
24°
Jun
31°
24°
Jul
30°
24°
Aug
30°
23°
Sep
29°
22°
Oct
29°
20°
Nov
28°
18°
Dec
Daily highs / lows in °C · bars show rain days per month · ERA5 climate normals (2020–2024)