For most of the year the air around Ubon Ratchathani is unremarkable. But from roughly February to April, agricultural burning across eastern Isaan -- and, at times, haze drifting in from neighboring Laos and Cambodia -- pushes PM2.5 up. Here's the honest, non-fabricated seasonal picture, plus the monitoring, purifiers, masks and apps residents rely on.
Like the rest of Isaan, Ubon Ratchathani sees a seasonal spike in haze driven mainly by rice-stubble and sugarcane burning, concentrated roughly February through April. Ubon Ratchathani also sits close to two international land borders -- Chong Mek to Laos and Chong Chom to Cambodia -- and agricultural burning across the border during the same dry-season window can add to the regional haze here, on top of domestic sources. Roughly May to October brings good air quality, while March and April are typically the watch months. 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 on both sides of the border. For the current reading, always check Air4Thai or IQAir directly. For the wider picture, see the Ubon Ratchathani hub.
These are directional, typical bands based on the wider Isaan dry-season burning pattern -- not measured monthly averages specific to Ubon Ratchathani. Always check a live AQI source (see below) for today's actual reading.
| Month | Typical AQI band | What's happening |
|---|---|---|
| January | Good → Moderate | Cool and dry; air is generally clean with only the earliest, localized burning |
| February | Moderate | Dry-season agricultural burning begins ramping up across eastern Isaan |
| March | Moderate → Unhealthy for Sensitive Groups (typical) | Usually one of the two worst months, as rice-stubble and sugarcane burning peaks across the region |
| April | Moderate → Unhealthy for Sensitive Groups (typical) | Burning and haze often continue through Songkran before easing late in the month |
| May | Moderate → Good | First monsoon rains begin clearing smoke and dust |
| June | Good | Monsoon established; one of the cleaner months of the year |
| July | Good | Reliably clean during the Candle Festival and peak rains |
| 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; occasional early haze |
| December | Moderate | Cool and mostly dry; generally calmer than the peak burning months ahead |
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 burning locally and across the border.
The primary source of Ubon Ratchathani's seasonal haze is domestic: farmers across eastern Isaan burn rice stubble and sugarcane residue each dry season to clear fields quickly and cheaply, typically from February through April. Ubon Ratchathani's location adds a second, plausible contributor most inland Thai cities don't share -- it sits near the Chong Mek crossing into Laos and the Chong Chom crossing into Cambodia, and both countries see their own dry-season agricultural burning over the same window. Smoke can drift across either border with the prevailing wind, similar to the cross-border haze that is well documented for other Thai border provinces. We haven't found reporting that quantifies exactly how much of Ubon Ratchathani's haze comes from across the border in a typical year, so treat it as a real but variable addition to the dominant domestic burning, rather than the main driver. March and April are typically the worst months, easing once the first monsoon rains of May 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. If you or a family member has a respiratory condition, weigh the February-April window seriously when deciding whether and when to be in Ubon Ratchathani, and lean on the precautions below during the worst weeks. See Ubon Ratchathani 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 citywide, and in bulk on Lazada and Shopee.
Thailand's Pollution Control Department (PCD) runs the national government monitoring network, reported through its Air4Thai service. Because Ubon Ratchathani's haze can have both domestic and cross-border origins, cross-checking against an independent aggregator is a useful habit here:
The official app and website from Thailand's Pollution Control Department (PCD), pulling readings from government monitoring stations nationwide, including Isaan. The authoritative local source for a real-time decision.
A widely used app blending official and independent-sensor data with live AQI, PM2.5 and short forecasts -- useful for a daily check and for comparing Ubon Ratchathani against neighboring Isaan cities.
A free web map aggregating monitoring stations across Thailand and the wider Mekong region, handy for seeing whether a spike is a local burning event or part of a broader regional haze episode.
Google, Apple Weather and similar surface a basic AQI figure -- fine for a glance, but the dedicated apps above are more accurate 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. Roughly May through October is generally good, in line with the wider Isaan monsoon pattern. The watch period is the dry season, broadly February through April, when agricultural burning pushes PM2.5 up across eastern Isaan -- March and April are typically the worst months.
The main driver is the same as across Isaan: farmers burn rice stubble and sugarcane residue each dry season to clear fields quickly and cheaply, mostly from February through April. Ubon Ratchathani also sits close to two international land borders -- Chong Mek to Laos and Chong Chom to Cambodia -- and agricultural burning in those neighboring countries during the same dry-season window can add to the regional haze, similar to the well-documented transboundary smoke that affects other northern and northeastern Thai border provinces. We haven't found province-specific reporting quantifying how much of Ubon's haze is domestic versus cross-border in a given year, so treat the cross-border contribution as a real but variable factor rather than a fixed share.
We deliberately don't publish invented daily or monthly figures here -- real readings vary year to year with rainfall, wind and how much burning is happening locally and across the border. For the current reading, check Air4Thai (Thailand's official PCD source) or IQAir/aqicn.org directly rather than relying on any static number, including anything you read elsewhere.
The authoritative source is Thailand's Pollution Control Department (PCD), which operates the national monitoring network reported via Air4Thai. IQAir and aqicn.org aggregate PCD data alongside independent sensors, which is useful for judging whether a spike is a local event or part of a wider regional haze episode.
If you live there through the February-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 citywide and in bulk on Lazada and Shopee.
Check live AQI before you decide how to spend a February-April day, then find the right Ubon Ratchathani home for how you want to live.
Hero photo by Frank van Dijk on Pexels.