For most of the year the air around Sukhothai is unremarkable. But from roughly January to April, agricultural burning and forest fires across the lower-north region push PM2.5 up — and in April 2026, Thailand's Pollution Control Department named Sukhothai one of eight provincial "red zones" alongside Chiang Mai and Chiang Rai. Here's the honest, non-fabricated seasonal picture, plus the monitoring, purifiers, masks and apps residents rely on.
Sukhothai sits on the flatter plains of the lower north rather than in a mountain-ringed valley like Chiang Mai — but every dry season it still gets swept into the same regional crisis. Roughly May to October/November brings good air quality, in line with the wider region's monsoon, while January to April is the watch period, with February to April typically worst. We deliberately don't invent precise daily or monthly AQI figures on this page — real readings vary year to year with rainfall, wind and burning intensity. What we can say with confidence, and cite directly: Thailand's Pollution Control Department reported on April 21, 2026 that 24-hour average PM2.5 readings across the north ranged from 38.7 to 132.0 µg/m³, and named Sukhothai one of eight provincial "red zones" posing health risks, alongside Chiang Rai, Chiang Mai, Mae Hong Son, Lamphun, Nan, Phayao and Phitsanulok. For current readings, always check Air4Thai or IQAir directly rather than a static number. For the wider picture, see the Sukhothai hub.
These are directional, typical bands based on the wider lower-north dry-season burning pattern and the verified April 2026 red-zone event — not measured monthly averages specific to Sukhothai. Always check a live AQI source (see below) for today's actual reading.
| Month | Typical AQI band | What's happening |
|---|---|---|
| January | Moderate → Unhealthy for Sensitive Groups | Dry season sets in; agricultural stubble-burning and early forest fires begin building across the lower north |
| February | Unhealthy for Sensitive Groups (typical) | Burning intensifies across Sukhothai and neighbouring upland provinces; smoke starts drifting in from further north |
| March | Unhealthy for Sensitive Groups → Unhealthy (typical) | Usually among the worst months, as forest fires in the mountainous provinces to the north combine with regional crop burning |
| April | Unhealthy for Sensitive Groups (typical) | Still smoky in many years — Sukhothai was named a PCD 'red zone' alongside Chiang Mai and Chiang Rai as late as April 21, 2026 |
| May | Moderate → Good | Early pre-monsoon storms begin knocking down the haze |
| June | Good | Monsoon established; one of the cleaner stretches of the year |
| July | Good | Reliably clean, rainy conditions |
| August | Good | Among the cleanest months of the year |
| September | Good | Peak monsoon; clean air continues |
| October | Good → Moderate | Rains taper off; air stays largely clean |
| November | Moderate | Dry season returns; readings start to creep up |
| December | Moderate | Cool and mostly dry; early burning activity can begin pushing some days higher |
US AQI reference: 0–50 good · 51–100 moderate · 101–150 unhealthy for sensitive groups · 151–200 unhealthy · 200+ very unhealthy/hazardous. Any given year varies with rainfall, wind and the intensity of regional burning.
Each year from roughly January to April, farmers across Sukhothai province burn rice stubble and other crop residue to clear fields quickly and cheaply ahead of planting. Sukhothai itself is on relatively flat plains — it doesn't have Chiang Mai's mountain-bowl effect that physically traps smoke over one city. But the province borders more mountainous, heavily forested territory to the north and west, where seasonal forest fires are common, and it sits within the same broad lower-to-upper-north airshed that gets blanketed in regional haze each dry season. That's exactly why, on April 21, 2026, Thailand's Pollution Control Department classified Sukhothai as one of eight provincial "red zones" for PM2.5 health risk — grouped with genuinely mountainous, higher-elevation provinces like Chiang Rai, Chiang Mai, Mae Hong Son, Lamphun and Nan, plus neighbouring Phayao and Phitsanulok. The PCD reported that day's national 24-hour PM2.5 readings ranged from 13.4 to 132.0 µg/m³ across all of Thailand, with the north specifically running 38.7 to 132.0 µg/m³ — well above the national 24-hour standard of 37.5 µg/m³ (tightened from 50 µg/m³ in 2023 to align with WHO guidance). February to April are typically the worst months, easing once the first storms of the May monsoon arrive.
Short-term exposure to burning-season smoke commonly causes irritated eyes, a scratchy throat, coughing, headaches and worsened allergy symptoms. Prolonged exposure to elevated PM2.5 is linked to more serious respiratory and cardiovascular effects, and the risk is highest for children, the elderly, pregnant women and anyone with asthma or existing lung or heart conditions. Thai authorities specifically advised the public to limit outdoor activity and use protective measures during the April 2026 red-zone event. If you or a family member has a respiratory condition, weigh the January–April window seriously when deciding whether and when to be in Sukhothai, and lean on the precautions below during the worst weeks. See Sukhothai healthcare for clinics and hospitals.
A HEPA air purifier is the single most effective thing you can do for indoor air. Size one to your bedroom (check the CADR — clean-air delivery rate) and run it continuously through the burning season. Stock spare filters early. Approximate Thailand prices:
| Option | Price (THB) | Best for | Notes |
|---|---|---|---|
| DIY box-fan + HEPA (Corsi–Rosenthal) | ~1,500–2,500 | Bedrooms on a budget | A box fan taped to one or more HEPA filters — cheap and effective; filters are the main running cost. |
| Xiaomi / Mi Air Purifier 4 Lite / 4 | ~3,500–7,000 | Bedrooms & small living rooms | The common value pick for Thai homes — real HEPA, an app, and a live PM2.5 display. |
| Philips / Sharp mid-range | ~8,000–16,000 | Larger living rooms | Higher CADR for open-plan spaces, with genuine HEPA and quieter high-speed operation. |
| Blueair / IQAir / premium | ~20,000–55,000+ | Whole-home / sensitive lungs | Top-tier filtration for asthma, young children, or a sealed 'clean room' during the worst weeks. |
Prices are indicative and vary by retailer and promotion (Lazada, Shopee, Power Buy, HomePro).
For outdoor protection, only a properly fitted N95, KN95 or FFP2 respirator filters fine PM2.5 — ordinary cloth and surgical masks do little against smoke. A good mask seals snugly around the nose and cheeks with no gaps; facial hair breaks the seal. Buy child-sized masks for kids, replace masks once damp or dirty, and keep a supply at home before the season peaks. They're sold cheaply in pharmacies and convenience stores in New Sukhothai town, and in bulk on Lazada and Shopee.
Thailand's Pollution Control Department (PCD) operates the official government monitoring network reported through Air4Thai — the same network that named Sukhothai a red zone in April 2026. Independent community sensors, tracked through IQAir, add coverage across Sukhothai town, Sawankhalok, Khiri Mat, Kong Krailat and several other districts. Together they feed the apps below:
The official app and website from Thailand's Pollution Control Department (PCD), which classified Sukhothai as one of eight provincial 'red zones' in its April 2026 nationwide report. The authoritative local source — check it, not a guess, before deciding whether to mask up.
Blends PCD and independent-sensor data with live AQI, PM2.5 and short forecasts. IQAir's own coverage of Sukhothai draws on stations in Sukhothai town, Sawankhalok, Khiri Mat, Kong Krailat and several other districts, plus community contributors — useful for comparing conditions across the province rather than relying on one point.
A free web map aggregating Thailand's official PCD network alongside independent sensors, handy for checking whether a spike is local to Sukhothai or part of the wider lower-north event.
Google, Apple Weather and similar surface a basic AQI figure. Fine for a glance, but the dedicated apps above are more accurate for Sukhothai and give more context.
Primary and official sources are cited above. Government rules, fees and procedures in Thailand change over time and vary by office; always confirm current requirements with the relevant authority before relying on them. BAANLYY never takes paid placement in editorial content.
No. For roughly seven months of the year — May through October or November — air quality in Sukhothai is generally good, in line with the wider region's monsoon pattern. The problem window is the dry season, roughly January through April, when agricultural burning and forest fires across the lower-north region push PM2.5 up, with February through April typically the worst stretch.
Broadly January to April, with the heaviest smoke usually falling between February and April. Farmers across Sukhothai and neighbouring provinces burn rice stubble and other crop residue to clear fields cheaply ahead of planting, while forest fires in the more mountainous provinces to the north add further haze that drifts across the region. Unlike Chiang Mai's mountain-ringed valley, Sukhothai sits on flatter terrain, but it still gets swept into the same seasonal crisis — Thailand's Pollution Control Department named Sukhothai one of eight provincial 'red zones', alongside Chiang Rai, Chiang Mai, Mae Hong Son, Lamphun, Nan, Phayao and Phitsanulok, in its 24-hour air-quality report on April 21, 2026.
We deliberately don't publish invented daily or monthly figures here, since real readings vary year to year with rainfall, wind and burning intensity. One verified, dated data point: Thailand's Pollution Control Department reported on April 21, 2026 that 24-hour average PM2.5 readings across the north ranged from 38.7 to 132.0 µg/m³, with Sukhothai among the eight provinces classified as a health-risk 'red zone' that day — well above the national 24-hour standard of 37.5 µg/m³. For the current reading, check Air4Thai (Thailand's official PCD source) or IQAir directly — don't rely on any static number, including this one, for a real-time decision.
The authoritative source is Thailand's Pollution Control Department (PCD), reported through its Air4Thai service and network of government monitoring stations nationwide. IQAir aggregates PCD data alongside independent community sensors — its Sukhothai coverage includes stations in Sukhothai town itself, Sawankhalok, Khiri Mat, Kong Krailat and several other districts — giving several cross-checkable readings around the province rather than a single source.
If you live there through the January–April season, a HEPA purifier for your bedroom is a sensible, low-cost investment — a budget Xiaomi unit (roughly 3,500–7,000 THB) or an even cheaper DIY box-fan-and-HEPA build covers a room well. Those with asthma, young children or other respiratory sensitivities often add a higher-end unit and run it continuously through the worst weeks.
Only a properly fitted N95, KN95 or FFP2 respirator filters fine PM2.5 particles — cloth and standard surgical masks don't. Look for a snug seal around the nose and cheeks, get child sizes for kids, and replace masks once damp or dirty. They're sold in pharmacies and convenience stores in New Sukhothai town and in bulk on Lazada and Shopee.
Check live AQI before you decide how to spend a January–April day, then find the right Sukhothai home for how you want to live.
Hero photo by Ian Wheldale on Pexels.