March
The wall. Ride early, stop at two, and expect white where the view was.
Smoke is worst in the still afternoon, so the clock matters more than the direction.
The calendarBurning season
ช่วงเผา
The two months of the year this ride has a reason not to happen.
What it is
Roughly late February to late April, agricultural and forest burning fills the valleys of upper northern Thailand and adjacent Myanmar with smoke. It ends with the first rains.
The long version
The measured shape, from four years of daily figures at ten points on the circuit: February is still fine up-country — Pai's February mean is 15.0 µg/m³ and not one February day in four years exceeded the US 24-hour standard there. March and April are the wall. Pai's April mean is 29.8 µg/m³ and all thirty April days measured were above that standard. May is over — Pai drops to 10.0 and stays down.
Chiang Mai runs worse than any town on the loop through the whole of it: a March mean of 37.8 µg/m³ against Mae Hong Son's 29.1.
Inference — if the dates are fixed and they land here, the ride still works; it is the views that do not. Plan shorter days, ride early, and treat the viewpoints as a bonus rather than the itinerary.
By season
April
The worst month measured, and the hottest.
Runs with
- storyThe smoke — The data and where it is weak.
- hazardRiding in the smoke — What it does to you on the bike.
- eventThe rains — What ends it.
- eventThe hot season — The same months, from the thermometer's side.
Named here by
- hazardRiding in the smoke — The dates.
- eventThe hot season — The same months, from the air's side.
- eventPoy Sang Long — The months it shares.
- eventSongkran — And the same days, from the air.
- eventThe rains — What it washes away.
- storyThe smoke — The season itself, as a date range.
Where each claim comes from
| Field | Tier | Source | Note |
|---|---|---|---|
| default | harvested | Open-Meteo Air Quality API (Copernicus CAMS) — Open-Meteo | |
| text_th | inference | written in Thai by this project, not machine-translated |
Sources
- Open-Meteo Air Quality API (Copernicus CAMS) — Open-Meteo
- Southeast Asian haze — Wikipedia (en)
- Final Reconsideration of the National Ambient Air Quality Standards for Particulate Matter — US Environmental Protection Agency
cited Cited — a named source, linked · harvested Harvested — fetched from an open dataset, with its licence · tradition Tradition — general knowledge of the tradition, hedged · inference Inference — this project's own reasoning from the above · field Field — someone stood there