I'm a bicyclist. It's handy for me to know what time it might rain, how likely it is to rain, and how much rain to expect. To discover this information, I like to check my local airport's terminal aerodrome forecast (TAF). Such an aviation weather forecast includes richer precipitation predictions than an ordinary "hourly forecast".

A raw TAF looks like this:

TAF BIKF 101933Z 1021/1121 30012KT 9999 BKN040 BECMG 1021/1024 14018KT BECMG 1102/1104 12028G40KT 6000 RADZ SCT010 OVC015 TEMPO 1103/1112 2500 +RADZ BR OVC008 BECMG 1111/1113 19018KT BECMG 1117/1120 23022G32KT 9999 SHRA BKN012CB

You can use a "TAF decoder" web application or mobile app to decode it into a nice plain-English forecast. Splendid!

If you want to see what a decoded TAF looks like, check out the latest London Heathrow Airport TAF.

Most TAF decoder web applications show all times in UTC. Unfortunately, I don't think in UTC. I think in Eastern Time.

Fine. Using a carefully worded Google search, I found http://www.flightutilities.com/MRonline.aspx, which fetches and decodes METARs (weather observations) and TAFs (aviation weather forecasts). And it even converts all the times into local time. But it was written in Italy, so it doesn't use the 12-hour clock which Americans use.

The lack of 12-hour notation makes the web application annoying to use. So I'd like an alternative.

So, in order from most to least important, I am looking for:

  1. A TAF decoder.
  2. Converts all times into local time.
  3. Uses 12-hour notation.
  4. Costs US$3 or less. (Or ad-supported.)
  5. Has nicely laid-out output, including graphical icons to represent things like "sunny" and "showers", and color-coding for TAF "Temporary" and "Becoming" sections.
  6. Preferably web based. Or, if this is impossible, Windows 7 based.
  7. Doesn't just decode TAFs, but also fetches them too.
  8. Open source.

[Edit: Hmmm. Maybe I should just email some feature requests (or patches) to the developers of some existing open-source TAF decoders.]


1 Answer 1


My recommendation doesn't match your specific question (TAF), but handles your overarching goal - to find out when it will rain, how much, etc. with sufficient detail.

I'd recommend http://forecast.io. It's an open web app, and gives contextual information over the next hour and week, including how much, wind speeds, etc. I use it heavily as a runner.

They also offer "Forecast Lines" which indicates multiple data sources and a best-guess used in their predictions. This has the benefit of indicating uncertainty.

  • I clicked your "Forecast Lines" link, then I clicked "Precipitation" at the top of the page. It gave me a graph of predicted rain over the next 24 hours, in millimeters per hour. This is really excellent. Much appreciated! +1 and accepted. Commented May 12, 2015 at 0:02

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