Alishan (Alishan National Scenic Area) weather in September
September in Alishan: nice, soaked, with muggy air — fine if you can take 23 rainy days.
Updated September 2026 · climate normals from ERA5 reanalysis
#12 of 12 months in Alishan · #977 of 1413 destinations to visit in September · comfort 68/100 (tier C)
- Days
- 19°C
- Nights
- 13°C
- Wet days
- 23
- Sun
- 9.3 h
- Humidity
- 88%
- Daylight
- 12 h

Traveller notes on Alishan in September
Alishan-forum threads on sunrise viewing are direct results here are genuinely inconsistent, one traveler reporting a great sunset but an underwhelming, cloudless sunrise the same trip, another describing thick fog ruining the sunrise while catching a genuine sea of clouds elsewhere on the same itinerary. Posters call September part of the broader wet season, a real chance of lingering shower activity even as the worst of typhoon season winds down. Regulars recommend building at least two mornings into any stay to improve the odds of catching a clear sunrise, a single attempt genuinely a gamble this time of year. Layers are standing advice given how much temperatures swing between a mild afternoon and a genuinely cold pre-dawn wait. Posters call the forest railway and cypress groves worth the trip regardless of whether sunrise cooperates. The record: 19.2C days feeling like 20C, 13.4C nights, an extraordinarily high 219mm across nearly 23 days and 88 percent humidity.
Other months in Alishan
Alishan-forum threads on whether real winter wear is needed in January are unambiguous: yes, posters calling readings commonly single digits or close to zero, thick, puffy layers standing advice regardless of how mild Chiayi or Taipei feel. Regulars call a proper parka and thermal base layers genuinely useful, mornings and evenings considerably colder than the daytime peak. Posters describe mountain areas as running a few degrees cooler and windier than general figures suggest, Alishan's elevation adding a real chill. Regulars call the sunrise viewpoint specifically brutal before dawn, real cold-weather gear essential for the wait. Posters recommend layering rather than one heavy coat, temperatures climbing considerably once the sun is up. Regulars call the cypress forest walks still rewarding in January despite the cold, fewer crowds a genuine upside. The record: 11.9C days feeling like 11C, 4.9C nights, 96.2mm across nearly 17 days and 82 percent humidity.
Alishan-forum threads on sunrise temperatures describe conditions at the summit viewpoint as genuinely cold regardless of how mild Chiayi feels below, posters calling readings in the single digits Celsius entirely plausible for the early wait. Regulars call the sunrise train departure around five-thirty standard, staying overnight strongly preferred over a lengthy pre-dawn drive up. Regulars describe daytime temperatures as considerably milder once the sun is up, a real layer system working better than one heavy coat given the swing. Posters call late February through June broadly the favored stretch, typhoon season from July into early October a real reason to avoid later months. Regulars recommend booking sunrise train tickets well ahead, capacity limited and demand high. Posters call the cypress forest walks worth the visit independent of the sunrise. The record: 17.2C days feeling like 18C, 9.9C nights, an extraordinarily high 182.5mm across nearly 24 days and 82 percent humidity.
Alishan-forum threads on March weather describe daytime readings as generally mild but genuinely cold at night, posters citing single-digit overnight lows especially when a system moves through the wider region. Regulars call parka-style layers and proper thermal wear standing advice, mornings and right after sunset both considerably colder than the daytime reading suggests. Posters describe the famous sunrise viewpoint as running noticeably colder still, its higher elevation meaning conditions there rarely match a general Alishan forecast. Regulars call March genuinely good timing for cherry blossoms, the bloom regularly overlapping with this stretch. Posters describe fog and a passing shower as fairly common in the mountains despite the otherwise favorable reputation. Regulars recommend real cold-weather layers regardless of the lowland forecast. The record: 14.9C days feeling like 15C, 7.4C nights, an extraordinarily high 137.6mm across over 21 days and 80 percent humidity.
December at Alishan is a different climate from the rest of Taiwan: the mountain runs 10 to 15C colder than sea level, so a 12 to 17C day in the cities is around 10C or below up here, and mornings and evenings are properly cold. The packing list regulars give is long trousers, layers, a jacket and a scarf, with gloves if you are going up for the sunrise. That sunrise is why most people come - the train from Alishan station up to Zhushan - and the honest warning attached is that the mountain is shrouded in cloud most mornings, so a good many visitors see nothing. The record: 13.3C days that feel like 12C, 6.5C nights, 16.6 precipitation days carrying 71.3mm and 8.6 hours of sun.
Add your own note from Alishan's card on the map.
Alishan climate normals — September
Monthly averages from ERA5 reanalysis. AQI is the mean US Air Quality Index for the month.
Crowds in Alishan in September
How busy the place itself is — school and mass holidays, the months an editor tagged, and how sought-after the weather makes them. Never part of the comfort score.
Quietschool holidays in 3 of the markets that fill it, one of its worst months for weather(estimated)
Peak crowdsBusyShoulder seasonQuiet
Best months for Alishan's weather
Ranked by this destination's own climate comfort score across the year — a different thing from how busy it gets (see Crowds above).
Toughest weatherAlishan's best weather comes in February, November and December — separate windows, not one continuous season.
September coincides with Typhoon and landslide season.
Best weatherFair weatherToughest weather
What's on in Alishan in September
Recurring seasonal events, natural spectacles, closures and holidays — curated and sourced.
- Hazard
Typhoon and landslide season
1 Jul – 15 Oct · usuallyTyphoon seasonClosuresThe mountain road and the forest railway are the first things to shut when a system parks over the island. Repairs can take a season, so check the line is running before you plan around it. Source ↗
- Season
Wet season
MonsoonRisk23 rainy days and about 374 mm in the month — the real kind of rainy season, not afternoon showers.
from the climate normals
Nearby, and something's on
Within 300 km of Alishan — a day trip or a short hop — with something on this month. Never part of the comfort score.
Where is Alishan?
Alishan in September — FAQ
- Is September a good time to visit Alishan?
- September in Alishan: nice, soaked, with muggy air — fine if you can take 23 rainy days. It ranks #12 of 12 months for Alishan on SeasonMap's comfort score (68/100).
- What is the weather like in Alishan in September?
- In September, Alishan averages a daily high of 19.2°C and a low of 13.4°C, with about 374.4 mm of rain over roughly 23.3 rainy days.
- What is the air quality in Alishan in September?
- Alishan has a mean US Air Quality Index of about 57 in September.
Within 300 km: Sun Moon Lake's Cross-lake Swimming Carnival around 10 Sep – 5 Oct, and Kenting's Raptor migration around 25 Sep – 25 Oct.