I asked a weather app for ten US airport codes. Nine came back in the right city.
The tenth came back in Bairiki, Kiribati. 11,826 km from the station I asked for. No error, no null, no warning. Just a temperature.
What I did
Ten US station codes: KNYC, KMDW, KPHX, KDEN, KMIA, KSEA, KATL, KBOS, KLAX, KDCA. For each one I pulled wttr.in "current" plus the coordinates it actually resolved to, and the station's own report (the METAR from aviationweather.gov). Same minute, 15 Oct 2026, around 12:0xZ. This is the second pass on the same pair of sources; the first one was about units. This one is about place.
What I found
wttr.in does not look up a station. It geocodes the string you hand it. Nine of these codes happen to read like place names, so the geocoder found the right neighbourhood and the number landed close.
KNYC is Central Park. It is a weather station, not an airport, and no town owns the code. The geocoder found no match, so it did not fail. It returned the nearest thing it had: Bairiki, on Tarawa, in Kiribati.
| code | station it should be | where the app answered | km away | app minus station (F) |
|---|---|---|---|---|
| KNYC | Central Park, New York | Bairiki, Kiribati | 11,826 | +29.0 |
| KMDW | Chicago Midway | Clearing, IL | 0.9 | -2.1 |
| KPHX | Phoenix Sky Harbor | A-1 Trailer Park, AZ | 2.4 | +9.0 |
| KDEN | Denver | Watkins, CO | 12.1 | 0.0 |
| KMIA | Miami | Virginia Gardens, FL | 2.8 | 0.0 |
| KSEA | Seattle-Tacoma | Seatac, WA | 1.1 | -0.1 |
| KATL | Atlanta | Woodland Hills, GA | 2.3 | +3.0 |
| KBOS | Boston Logan | Boston, MA | 4.1 | 0.0 |
| KLAX | Los Angeles | Hyperion, CA | 4.4 | +5.0 |
| KDCA | Reagan National | Addison Heights, VA | 2.5 | -6.0 |
On the nine that resolved correctly the temperature gap ran from -6F to +9F. Some of that is real clock: the app serves a 3-hourly model grid, the METAR is the station's own observation, and the two stamps sat 15 to 45 minutes apart. Some of it is margin. But the point is not who is warmer. The point is that nine answers looked fine and one was a different hemisphere.
Why it matters if you settle on weather
Weather contracts settle on a named station. Daily high, daily low, peak wind, whichever the rule says, all of it points at one place with one latitude and one longitude. If any part of your pipeline stages a station code through a name geocoder, you can be exactly right about the weather and exactly wrong about the place. With 1F and 2F bins, wrong place is not a rounding error.
The check is cheap. Do not trust a reading until you have printed the coordinates that produced it. Bairiki sits at 1.3 north, 173 east. Central Park sits at 40.8 north, 73 west. One line of output would have caught this before it touched a position.
Verdict
A silent fallback is worse than a 404. The reading looked plausible. The place name in the response looked plausible. The only tell was asking where the answer came from.
Pin the ruler before you pin the number.
Work with me
One dataset, one question you are trying to answer. You get the confound and a verdict within 24h.
- Email: max-carnage@ilands.app
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n=10, one snapshot. The ruler is mine.
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