Smoke Calendar for Digital Nomad Bases: Which Months Are Hazy, Place by Place

Which months are smoky or hazy, place by place?

The short version: pick your month first, then your place. In our model data the smokiest months are November to March in Kathmandu, January to March and October in Bangkok, March in Chiang Mai, and almost every month in Hanoi and Kuala Lumpur. The table below gives the average PM2.5 (fine particles, in µg/m³) for each calendar month, averaged over 2023, 2024 and 2025, for 20 nomad bases. Very smoky months (35 and over) are the darkest cells. All figures are model estimates, see the method note.

Read it along a row to see a place's year, and down a column to compare places in the month you plan to travel. The clearest rows are the Thai coasts, Canggu, Langkawi, Playa del Carmen and Oaxaca, which stay under about 15 in nearly every month; the only months at 15 or more are January and March on Koh Samui (15) and May in Oaxaca (18).

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Which places have a smoke season you can plan around?

Only some of these places have a season. The rest are smoky all the time, or never. The table lists the months that reach the smoky band (25 to 34) and the very smoky band (35 and over) for the places that have any.

Three patterns matter for timing. Burning seasons are short and predictable: Chiang Mai peaks in March and is back under 15 from June to August (see the week-by-week view in our Chiang Mai burning season guide). City smog sits on Hanoi, Bangkok and Kathmandu in the cool, calm months and washes out with the monsoon in Bangkok and Kathmandu, but not in Hanoi. Regional haze lifts Kuala Lumpur for most of the year; Penang and Langkawi, an hour or two away, read much lower. For the causes, open the place guides: Hanoi, Bangkok, Kathmandu, Malaysia and Bali.

Chiang Mai's peak moves from year to year. February to April in each year of our data, including 2026:

How do you use the calendar to plan?

1. Find your month in the column, not the yearly average. A place that is clean in July can be among the worst in March.
2. Check the neighbours. If your base is in a smoky or very smoky band, look for a place that is clear in the same month. In March, for example, the Thai coasts are in the clear band while Chiang Mai is in the very smoky one.
3. Add weather. Clean air often comes with rain. Our cleanest air by month page compares 17 places on the same data for the winter and summer months, and the Chiang Mai weather guide covers heat and rain.
4. Keep a margin. Years differ a lot. A three-year average says when smoke is likely, not how bad one particular year will be.
5. Look at a live reading before you book and on arrival. This is history, not a forecast. If PM2.5 versus AQI confuses you, see PM2.5 or AQI.

We give no health advice. If you are sensitive to polluted air, ask a doctor before planning a long stay.

Method note: what these numbers are and are not

• Source: the Copernicus Atmosphere Monitoring Service (CAMS) global air-quality model, read through Open-Meteo (CC BY 4.0). One point per place, hourly PM2.5.
• Daily and monthly values: a day counts when it has at least 18 hourly values; the monthly figure is the mean of those days. The calendar value is the mean of the same month in 2023, 2024 and 2025, rounded to a whole number. Where the underlying data for a place is incomplete, the cell says n/a.
• Bands: under 15 clear (the WHO 2021 24-hour guideline), 15 to 24 hazy, 25 to 34 smoky, 35 and over very smoky. They are our own cut points on a monthly average, not a health standard and not an AQI category. The WHO annual guideline is 5.
• Model, not a sensor: the grid is roughly 45 km. On bad days the model reads low, in our checks about a third of station values on the worst days, and it smooths away neighbourhood differences. Use it to compare months and places, not to judge one day.
• Window: three years is short. It shows the usual season, not a trend.

How to cite this page

Free to quote, in an article, a newsletter or a talk. Please say "model estimate" and link here.

NomadWeather (2026). Smoke calendar for digital nomad bases: monthly fine-particle averages, model estimate for 2023 to 2025. https://www.nomadweather.com/guides/smoke-calendar-nomad-bases

The same table as a spreadsheet: nomad-smoke-calendar.csv. Data credit: CAMS via Open-Meteo, CC BY 4.0. Questions or corrections: hello@nomadweather.com.

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