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Show HN: Error in official Swiss weather forecasts, recorded since September '25forecasterror.xlit.app

Hi. In summer 2025, I got a bit disappointed that many days ended up hotter than they were forecast, and decided to quantify this to see how "bad" is it. So I started recording. I took forecasts for Bern and Zürich at…

1 points•ghasemi•2 days ago•1 comment•
#forecasts#swiss#september#recorded#error#official#since#weather
Hi. In summer 2025, I got a bit disappointed that many days ended up hotter than they were forecast, and decided to quantify this to see how "bad" is it. So I started recording.

I took forecasts for Bern and Zürich at the end of the day (~10PM), so that the forecast for the current day is not anymore "a forecast", and then also predictions of temperature and precipitation for up to 7 days.

A few weeks ago, I put a web app on top of it for easier navigation. You can check the history of forecast errors in these two/three (min/max temperature, precipitation) for Bern and Zürich in Switzerland. I may start recording other cities too.

I thought someone else may find this interesting. Any feedback, flaw, etc is more than welcome.

Best

1 comment

ggm2 days ago
What I read from this is that their model lies within +/- 2 degrees most of the time. I assume therefore it's adjusted to reflect observations, and thats the error limit they set as a target.

I don't think this is "bad" per se.

Read the full thread on Hacker News →

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