Chiang Mai Burning Season 2026: Air Quality Guide & What to Do

If you're planning to visit Chiang Mai in March or April 2026, you need to read this first.

Northern Thailand's burning season is real. Every spring, farmers burn crop stubble and forests across the region, creating a blanket of smoke that turns the sky orange and makes breathing feel like inhaling smoke. Air quality indices hit "unhealthy" or worse for weeks. In April 2025, Chiang Mai's AQI topped 350 multiple times — worse than any major city on Earth.

This guide covers what burning season is, which areas are affected, who should skip it entirely, and how to protect yourself if you're already committed to going.

What Is Burning Season? (And Why It Happens)

Every February through April, farmers across northern Thailand (and Laos, Myanmar, Cambodia) burn crop residue from rice paddies and corn fields. It's quick, cheap, and traditional — but it creates an enormous amount of smoke.

Where the smoke comes from:

• Thailand: Chiang Mai, Chiang Rai, Mae Hong Son, Lampang, Lamphun provinces
• Myanmar/Laos: Cross-border smoke drifts into northern Thailand from neighboring countries
• Wind patterns: Cool, dry season winds push smoke south and east toward populated areas

Timing:

• February: Light burns, occasional haze
• March: Burning intensifies, AQI rises to 100-150+
• April: Peak burning, AQI often 200-300+, sometimes over 350
• May: Rains arrive, smoke clears within days

Which Areas Are Affected? (Worst to Least)

WORST: Chiang Mai (The Epicenter)

• AQI in April 2025: Peaked at 350+ on multiple days (top 5 worst air in the world)
• Visibility: On bad days, you can't see more than 100 meters
• How long it lasts: Mid-February through late April (10+ weeks of degraded air)
• Who lives there: 1.2 million people — most travelers avoid March-April now

SEVERE: Pai (Small Town in Chiang Mai Province)

• Why it's worse than expected: Mountain valley geography traps smoke like a bowl
• AQI in April 2025: Often 200-250, sometimes higher than Chiang Mai itself
• Tourist reputation: Known for backpackers and digital nomads — many were unprepared for bad air in 2025
• Escape route: Only road out goes through Chiang Mai (more smoke)

BAD: Chiang Rai

• AQI in April 2025: 150-250 range
• Why: Agricultural areas + proximity to Myanmar/Laos
• Escape: Head south to Phayao or further

VERY BAD: Mae Hong Son

• AQI in April 2025: 150-280
• Why: Rural, mountainous, surrounded by farms and forests
• Reality check: Beautiful area, but burning season is brutal
• Tourist factor: Less visited than Chiang Mai, so fewer prepared travelers

MODERATE: Lamphun, Lampang (South of Chiang Mai)

• AQI range: 100-180
• Why less bad: Further south, slightly outside the worst burn zones
• Skip if: You have respiratory issues; otherwise manageable with masks

RARELY AFFECTED: Bangkok

• AQI in April 2025: Usually 50-80 (normal range)
• Why: Southern location, different wind patterns
• Reality: Bangkok is hazy year-round from vehicle emissions, but burning season doesn't hit

CLEAR: Gulf Islands (Koh Samui, Koh Tao, Koh Phangan)

• AQI range: 30-70 year-round
• Why: Ocean winds blow smoke away from islands
• Tourist friendly: March-April is perfect island season

CLEAR: Andaman Region (Phuket, Krabi, Phi Phi)

• AQI range: 20-60 year-round
• Why: Far south, island geography
• Best escape route: Burn season in north = perfect conditions in south

The AQI Scale: What Do the Numbers Mean?

Air Quality Index (AQI) measures PM2.5 and other pollutants. Here's what each range feels like:

| AQI Range | Category | What It Feels Like | |-----------|----------|-------------------| | 0-50 | Good | Clear air, no issues | | 51-100 | Moderate | Slight haze, usually OK | | 101-150 | Unhealthy for Sensitive Groups | Noticeable air, people with asthma/elderly should limit outdoor activity | | 151-200 | Unhealthy | Air is visibly hazy, breathing noticeably harder, headaches common | | 201-300 | Very Unhealthy | Difficult to breathe outdoors, eye irritation, sore throat, everyone affected | | 300+ | Hazardous | Stay indoors. Breathing is painful. Emergency mask needed. |

In April 2025: Chiang Mai regularly hit the "Very Unhealthy" range (200-300) for weeks, with multiple days over 350 (Hazardous).

Who Should Avoid Burning Season Entirely?

SKIP CHIANG MAI in March-April if you have:

• Asthma or COPD: You'll suffer. Seriously.
• Respiratory conditions: Cystic fibrosis, bronchitis, severe allergies
• Heart disease: Air pollution worsens cardiovascular conditions
• Age extremes: Children under 5, adults over 65
• Pregnant: Pollution affects fetal development

Reality check: If you're in this category, reschedule your Chiang Mai trip to November-February (perfect weather, zero air quality issues). It's worth waiting.

HEALTHY but ANXIOUS? You'll likely be fine with precautions (see below). Millions of Thais live in Chiang Mai year-round. But expect headaches, sore throats, and eye irritation. It's not comfortable.

If You're Already Booked: Survival Strategies

Sometimes you've already paid for flights and accommodation. You're going anyway. Here's how to minimize damage:

1. Get the Right Masks (NOT Surgical Masks)

Wrong: Surgical/medical masks (they filter 60% of particles)

Right: N95 or KN95 respirators (filter 95% of PM2.5)

Where to buy in Thailand:

• 7-Eleven (yes, really — stocked during burning season)
• Boots
• Watsons
• Big C (hypermarket)
• Most pharmacies

Cost: 20-50B per mask (incredibly cheap)

How to use: Seal properly around nose and mouth. Loose fit = no protection.

Efficiency note: Masks work best if you're outside for short periods. Wearing them all day is uncomfortable and creates false security.

2. Stay Indoors 10am-4pm (Peak Haze Hours)

• Why: AQI peaks midday when temperature inversion traps smoke
• What to do instead: Work, read, nap, watch films, eat long lunches
• Productivity hack: Shift your day — 6am breakfast and walk before haze peaks, 5pm onward when AQI drops

3. Air Purifier in Your Room

• Ask your hostel/hotel: Many now have HEPA air purifiers in rooms (it's become a selling point post-2025)
• Cost: Usually no extra charge, or 500B/night if you need one added
• How it helps: Room becomes a safe haven with breathable air
• Leave it on: Even when you're out, so you return to clean air

4. Close Windows & Use AC

• Keep windows shut: Obvious but important
• AC filter: Make sure it's not clogged (ask hotel to check)
• Recirculate mode: AC on recirculate (not pulling in outside air) keeps indoor air clean

5. Check Air Quality Daily

Real-time monitoring apps/websites:

• IQAir (web and app): Detailed real-time AQI for any location in Thailand
• Aqicn.org: Global AQI database, very reliable for Thailand
• Chiang Mai Air Pollution Facebook group: Local updates, real-time reports from residents, sometimes community tips on where air is "less bad"

Strategy: Check at 8am, 12pm, and 4pm. Plan outdoor activities for the clearest window.

6. Keep Windows Closed When AQI Is High

• AQI under 100: Windows open OK
• AQI 100-150: Crack windows only, prefer AC
• AQI over 150: Sealed windows, AC only

7. Stay Hydrated & Support Your Respiratory System

• Drink extra water: Helps your body flush irritants
• Saline nasal spray: Clears irritated nasal passages
• Throat lozenges: Soothe sore throat
• Avoid smoking and secondhand smoke: Your lungs are already stressed

The Songkran Timing Problem (April 13-15)

Songkran is Thailand's New Year water festival — a massive celebration with water splashing, parties, and parades. It's incredible fun.

The problem: Songkran happens April 13-15, during peak burning season. Imagine a water festival in heavy smoke with an AQI of 250+. You're wet, you're breathing haze, your lungs are irritated.

Decision: If you want a full Songkran experience, consider celebrating it in Bangkok or the south instead. Or plan to visit Chiang Mai for Songkran but accept that the air will be rough.

The Alternative: Visit in November-February Instead

Here's the case for rescheduling:

• Air quality: Perfect (AQI 30-60)
• Temperature: Cool and pleasant (15-25°C at night, 25-35°C during day) — no sweltering heat
• Tourism: High season, lots of travelers and events
• Festivals: Yi Peng (November, light festival — absolutely magical with clear air)
• Hiking: Perfect weather for trekking
• Cost: Will be higher due to high season, but the experience is infinitely better

Reality: Chiang Mai in November-February is one of the best places on Earth in that season. Worth rescheduling for.

What Happens in May?

The moment the rains arrive (usually late April, early May), the burning stops and air clears within days.

• Dry season ends: Farmers can't burn (the land is wet)
• AQI drops: From 300+ to under 100 in 1-2 weeks
• Landscape: Transforms from orange haze to lush green
• Humidity: Returns

If you can push your trip to May 1st onwards, you'll catch the tail end of cool season AND have clear air.

Health Effects: What to Expect

Short-term (while you're in the smoke):

• Eye irritation (scratchy, red eyes)
• Sore or scratchy throat
• Headaches (especially if you're not acclimated)
• Dry cough
• Mild shortness of breath with exertion

With masks and precautions: Most of these reduce dramatically.

Long-term (if you stay months):

• Respiratory inflammation
• Exacerbation of asthma/allergies
• Increased risk of heart attacks (for those with existing conditions)
• Lower lung function

For a 1-2 week visit with precautions: You'll likely feel fine overall. Expect some irritation, but not serious damage.

Quick Decision Tree: Should I Go to Chiang Mai in March-April?

Do you have respiratory conditions (asthma, COPD) or heart disease?
├─ YES → Strongly consider rescheduling to Nov-Feb
└─ NO → Continue

Are you visiting March 1-31 or April 1-30?
├─ YES (late March or all of April) → Consider visiting islands instead
└─ NO (Feb or early March) → Go, but with precautions

Are you willing to:
  - Stay indoors 10am-4pm?
  - Wear N95 masks outdoors?
  - Use an air purifier?
  - Check AQI daily and plan accordingly?
├─ YES → You can make it work
└─ NO → Visit in a different season

The Upside: Travelers Who Know About This Are Rare

Here's the bright side: most backpackers don't know about burning season. The ones who do either skip March-April or prepare properly. If you're reading this, you're already ahead.

You'll encounter:

• Fewer tourists (less crowded)
• Cheaper accommodations (it's the "low season")
• Genuine local life (not high-season tourist zones)
• Opportunity to explore deeper

Just accept: The air will be hazy, and that's part of the experience.

Resources & Real-Time Monitoring

Air quality tracking:

• IQAir: Detailed maps, hourly forecasts, historical data
• Aqicn.org: Global database, very reliable
• Chiang Mai Air Pollution Facebook group: Community updates and strategies

Health resources:

• Thai Airways/buses: Many offer refunds or rescheduling if you can't travel due to air quality
• Travel insurance: Some policies cover "unexpected hazardous air quality" — check yours before booking

Masks & supplies:

• Buy masks in Chiang Mai (cheaper than online shipping)
• 7-Eleven, Boots, Watsons always have stock March-April

The Bottom Line

March-April burning season is real, and Chiang Mai air quality genuinely suffers. You have three smart options:

1. Skip Chiang Mai in March-April entirely. Visit islands (perfect weather) or reschedule for November-February.

2. Go to Chiang Mai, but prepare. Get N95 masks, book a room with an air purifier, check AQI daily, stay indoors midday. Accept some respiratory irritation.

3. Visit Chiang Mai later in April or early May when rains arrive and air clears (usually by May 1st).

The worst mistake: showing up unprepared in April, expecting clear skies, and spending two weeks fighting respiratory irritation. That's why this guide exists.

Safe travels, and breathe easy.