Why a designer in Milwaukee built a smoke radar
I am Ryan Thompson. I live in Milwaukee with my two sons, and I have spent most of my life outdoors: on trails, on a bike, at a campsite, at a ballfield on Saturday mornings.
I am an Eagle Scout. That sounds like a line on a résumé, but what it actually means is that somebody taught me young to leave a place better than I found it, and to check the weather before you take other people's kids into it.
So when the sky over the Midwest turns the colour of a bruise, I want a straight answer to a simple question: is it safe to be outside? Not a colour-coded badge. Not a number with no context. An answer.
The thing nobody tells you is that the sky lies. Some days it looks apocalyptic and the air at ground level is fine, because the smoke is riding three kilometres over your head. Some days it looks perfectly clear and the air is genuinely bad. Those are opposite situations and they look identical from your porch. SmokeDar exists to tell those two days apart, and to show you what is burning upwind and why.
I care about this because I care about the people and the living things downwind of it, including two boys who want to know if practice is on. It is free. It has no ads, no signup, and it sells nothing about you. It stays that way as long as people chip in.
I am a designer and developer, and I build things like this on my own. If you have something that needs making, I am open to working with you.
- Free, no signup, no ads, nothing sold
- Eight states, one 616-point grid, refreshed hourly
- 21 skylines drawn by hand, every state capitol included
- Aloft vs surface: the distinction almost nothing else makes
- Built in Milwaukee by one person, and free to use
Writing about wildfire smoke, air quality, or the Midwest sky? I will happily talk, on the record, and I have a press kit ready so you are not chasing me for facts.
What this is, honestly
I try hard to keep SmokeDar accurate. Everything in it comes from public, science-grade data, and I have been careful with it.
It is still not a health barometer, and it is not a medical device. It is a general picture of risk, and it is meant to be interesting to look at. The readings are modelled forecasts averaged over a grid about 77 km across. That is not a sensor on your street, and it cannot know anything about you.
If you have a real concern, talk to a real person. If you have asthma or a heart or lung condition, if you are pregnant, if you are caring for someone vulnerable, or if you are simply worried, speak to a doctor or your local health department. They know your situation. A webpage does not.
Use SmokeDar to notice things and to be curious. Do not use it to make a medical decision.
The things people actually ask
Is the smoke I can see the same as the smoke I am breathing?
Often not. Smoke aloft can ride two miles over your head and turn the sky orange while the air at ground level stays clean. The reverse also happens: a clear-looking day can carry genuinely bad air. SmokeDar shows the two separately, as aerosol optical depth for the sky and PM2.5 or US AQI for the surface.
What is aerosol optical depth?
It measures how much the entire column of air above you dims sunlight. High values mean a lot of particles somewhere overhead, at any altitude. It explains the colour of the sky. It does not tell you what is in your lungs, which is what PM2.5 measures.
Which states does SmokeDar cover?
Eight: Minnesota, Wisconsin, Michigan, Iowa, Illinois, Indiana, Ohio and Missouri. The region is sampled as a fixed 616-point grid at roughly 77 by 54 kilometre spacing, refreshed hourly.
Is SmokeDar free?
Yes. No signup, no account, no advertising, and no data is sold. It is funded by donations. A coffee covers about a month of running it.
Where does the data come from?
Smoke and air quality come from the Copernicus Atmosphere Monitoring Service via Open-Meteo. Fire data comes from the Canadian Wildland Fire Information System at Natural Resources Canada and from the US National Interagency Fire Center. All of it is public and free, with no API keys. Anyone can check the numbers.
Can SmokeDar tell me when the smoke will arrive?
No, and it deliberately will not guess. At a 77 kilometre grid resolution the smoke field changes strength in place faster than it visibly travels, so any arrival time calculated from it would be invented. Use the hourly and five day forecast instead, which comes from a real atmospheric model.
Why is there so much smoke in the Midwest?
Usually because Canada is on fire. Most smoke that reaches the Great Lakes starts hundreds of miles north in Ontario, Manitoba or Quebec, and rides the wind south. SmokeDar shows what is burning upwind right now, with the area alight and the distance from you.
Is SmokeDar medical advice?
No. It is not a health barometer and not a medical device. It indicates general risk and is meant to be interesting to look at. If you have asthma, a heart or lung condition, if you are pregnant, if you care for someone vulnerable, or if you are worried, speak to a doctor or your local health department. AirNow is the EPA's official source of record for US air quality.