Just when we thought this week’s weather couldn’t get any more intense…
Following a brutal mid-week heat wave and the city’s most significant Canadian wildfire smoke event since 2023, local forecasters warn that Saturday’s rainfall will bring a bizarre weather phenomenon called “dirty rain.” Instead of washing the city clean, tomorrow’s showers will likely leave behind a thin layer of soot, dust, and grime across the five boroughs.
Yes—it’s a real weather phenomenon, and it’s heading our way tomorrow, Saturday, July 18. Here’s what’s happening.
What exactly is dirty rain?
According to the National Weather Service, dirty rain—sometimes called muddy rain or red rain—occurs when rain pulls dust, smoke, ash, or other tiny particles suspended in the atmosphere down to the ground.
Because New York City’s skies are currently filled with smoke from the ongoing wildfires in Ontario, Saturday’s expected storms will act as an atmospheric filter, capturing the soot and leaving it on vehicles, streets, windows, and other outdoor surfaces.
Professional NYC meteorologist John Davitt explained the phenomenon on Twitter:
“Dirty rain” is expected Saturday in NYC. This is when there are high levels of smoke particles in the air and it rains. The smoke particles fall with the rain and leave behind a coating of soot on cars, streets, etc.
Saturday’s severe weather timeline
The National Weather Service has outlined a high probability of rain mixed with smoke for Saturday, July 18:
- Saturday Daytime: A slight chance of showers early, shifting to heavy showers and potential thunderstorms after 11 am. Expect visible areas of smoke aloft, a high near 82°F, and south winds gusting up to 23 mph. The overall chance of precipitation is 80%
- Saturday Night: Showers and thunderstorms will continue, primarily before 2 am. Lows will hover around 76°F with wind gusts reaching up to 25 mph. The chance of precipitation jumps to 90%, with up to three-quarters of an inch of rainfall possible
The Silver Lining: While the rain will leave a messy coating on outdoor surfaces, it’s expected to significantly clear the atmosphere, paving the way for vastly improved air quality by Sunday.
Is dirty rain dangerous to your health?
For most people, dirty rain itself isn’t considered dangerous.
However, the wildfire smoke triggering it remains a health hazard–especially for children, older adults, people with asthma or heart disease, and anyone who spends extended periods outdoors.
Air quality advisory remains in effect
The New York State Department of Environmental Conservation has extended the air quality health advisory through midnight tonight, Friday, July 17, as smoke continues affecting the region.
Air quality has already reached levels considered unhealthy for everyone—not just sensitive groups–since fine particulate matter can cause throat irritation, coughing, and shortness of breath.
Quick Safety Checklist:
- Protect Sensitive Groups: Children, older adults, pregnant individuals, and those with respiratory issues (like asthma) should minimize time outdoors until the system passes
- Recirculate Air: Keep windows closed and set your air conditioning units to recirculate indoor air rather than pulling in the smoky air from outside
Track real time local updates
Air quality levels will fluctuate right up until the storms roll through. Keep these links bookmarked to track the shift in your specific zip code:
- AirNow.gov: Check your local, real-time Air Quality Index (AQI) data
- Notify NYC: Sign up at nyc.gov/notifynyc or text NOTIFYNYC to 692-692 for instant emergency weather alerts
- DEC Daily Forecast: View official daily air quality updates directly from the New York State Department of Environmental Conservation