Where things stand
As of the Bureau of Meteorology's 29 September 2026 update:
- El Niño is near record strength. The key Pacific index reached +2.72 °C, the second-highest weekly value in the Bureau's records since 2008.
- It's expected to get stronger. Models forecast a peak in late spring or summer, most above +3.0 °C, lasting into autumn 2027.
- The Indian Ocean is lining up too. A positive Indian Ocean Dipole is likely to form this spring.
When El Niño and a positive Indian Ocean Dipole coincide, warmer and drier conditions become more likely across southern WA. Perth has already had a taste: just 56.8 mm of rain fell in July, against a July average of 144.3 mm.
A strong El Niño doesn't guarantee strong impacts, as the Bureau points out. Many factors shape our weather, so check its long-range forecast for the latest picture.
What it could mean for Perth's air
- More bushfire smoke. Hot, dry weather dries out bush and grass. Fire agencies have flagged high fire risk in parts of WA, with heavy fuel loads and soil moisture deficits that worsened over winter.
- An earlier, longer smoke season. Dry springs can bring fires forward. Morning easterlies can carry Hills smoke over the suburbs.
- More dust. Dry soils lift more easily on windy days.
- Hotter days indoors. Heatwaves keep windows shut and people inside, so the air inside your home matters more.
How a purifier helps
Smoke's real harm is fine PM2.5 particles, and that's exactly what a HEPA filter catches. In a study of smoke-affected homes, portable HEPA purifiers cut indoor fine particles by 55 to 65% on average.
- Size it for smoke. Smoke needs about five air changes an hour. Box claims assume one. Check your room.
- Get carbon. HEPA takes the particles; activated carbon takes the smell.
- Make a clean room. One room, door shut, purifier on high, is where you sleep on smoky nights.
- Close up first. Windows shut and the evaporative cooler off, or the purifier can't keep up.
What it won't do: a purifier doesn't cool the house, and HEPA filters don't remove gases. On hot, smoky days, use reverse-cycle air conditioning on recirculate alongside it.
Get ready before summer
- Fit a fresh filter now, and buy a spare. They can sell out when a big fire hits.
- Check your purifier is big enough for smoke, not just dust.
- Pick your clean room, usually the main bedroom.
- Buy P2 masks for trips outside.
- Check asthma and heart action plans with your GP.
- Bookmark Perth air quality today and Emergency WA.
Best purifiers for smoke Smoke-day plan
Sources
- Bureau of Meteorology: Southern hemisphere monitoring, ENSO and IOD update, 29 September 2026.
- Water Corporation: What is El Niño and how does it affect WA?, 27 August 2026.
- ABC News: Spring bushfire outlook, 19 August 2026, reporting the AFAC seasonal outlook.
- Barn P. et al. (2008). Infiltration of forest fire and residential wood smoke: an evaluation of air cleaner effectiveness.
General information, not medical advice. Outlooks change; the Bureau's latest forecast is the best guide.