Ask Axios: Why do we measure rain at the airport?
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Illustration: Maura Losch/Axios
A few readers have asked: When you report rainfall totals or a certain number of 90-degree days in Columbus, where do those weather measurements come from?
👋 Alissa here, our resident weather nerd. Our reporting uses records from the National Weather Service, the federal agency that collects and maintains official U.S. weather observations.
- In major metro areas, that data typically comes from an airport — and that's been the case in Columbus since 1930. (Before then, data came from downtown buildings.)
- I reached out to the weather service's Wilmington office, which has jurisdiction over Central Ohio, to learn why.
What I found: John Glenn International Airport houses a sophisticated Automated Surface Observing System (ASOS) site, one of nearly 1,000 nationwide managed by federal agencies. The real-time measurements help keep flights running safely.
- Airports are wide open areas and staffed 24/7, making them ideal collection locations.
- Having one "official" site keeps comparisons consistent over time.
Yes, but: The airport's weather can differ from what's happening across town.
The intrigue: The weather service also relies on radar and rain gauges throughout the region to compile more granular data.
- That includes gauges maintained by a network of trained volunteer observers, the Community Collaborative Rain, Hail & Snow Network.
- You can apply to join, but an official, $48 rain gauge is required.
The bottom line: Though 9.94 inches of rain "officially" fell in Columbus this August, that may not reflect what fell in your backyard.