I posted this question on StackOverflow here and terriblememory suggested I post it here. I didn't even know there was an aviation stack exchange. Cool!

I have been scowering the internet all day for a third-party weather API that reports more than just the cloud coverage for cloud information. I need to know the height of the cloud.

I need something like an aviation weather API that reports either the cloud height, the cloud max and min vertical position, or the cloud type (Cirrus, Stratus, Cumulus, etc.) from which we could then derive the relative height.

We want the API to be free at least during development.

I found some relative information in this stack exchange and one answer here that tells how to find the cloud tops but I'm posting this question anyway in case there is an API yet to be suggested.

Meanwhile, I'll be taking a look at the other information I found in this stack exchange. Thank you in advance for suggestions.

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    $\begingroup$ Normally, aviation weather reports (METARs) carry the cloud base height -- does this work for you? $\endgroup$ Jan 16, 2016 at 1:55
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    $\begingroup$ Do you need observations or is model forecast data adequate? $\endgroup$
    – casey
    Jan 16, 2016 at 3:29
  • $\begingroup$ I'm a programmer and we're looking for this information for Ballistic Missile accuracy. It may be possible that cloud base height might help. $\endgroup$
    – Patricia
    Jan 16, 2016 at 20:03
  • $\begingroup$ There has to be something out there else how would pilots know to climb to a destination altitude to get above the clouds? -> The kinds of aircraft that can easily get above the clouds are usually also those that are certified for flying in the clouds...so they don't really care. $\endgroup$
    – Steve V.
    Jan 17, 2016 at 21:08
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    $\begingroup$ METARs can be had quite easily from weather.noaa.gov/pub/data/observations/metar/stations. However METARs only have cloud base, for the layers visible from the ground and only up to certain altitude. So if there is an overcast layer, there is no information about any layers above it and if there are no clouds below 5,000 ft or 10,000 ft simply report "CAVOK" or "NSC" (no significant clouds). You may get CAVOK and it might still be overcast at 6,000 ft. $\endgroup$
    – Jan Hudec
    Jan 18, 2016 at 6:14

2 Answers 2


Short answer:

I wish this information were available, but what you are looking for is simply not available.

Longer answer:

There has to be something out there else how would pilots know to climb to a destination altitude to get above the clouds?

You are looking for data that you rightly think should exist. I would that it did, but it doesn't. Thats where the art of airmanship comes in. The answer to your question I quoted above is a complex mix of years of experience reading the weather charts, eyeballing the view out the window, and networking through the radio.

Real world weather is too hard to predict, and is constantly in flux. The only way to know the actual cloud conditions is to get out there and see it in the moment. The ground based weather observation stations like AWOS and ASOS do a decent job, but they are very limited and often wildly inaccurate. They only provide an assessment what is visible straight up.

PIREPS are the only partial answer you will get, and these are sparse and dated. A PIREP is only a snapshot of what a pilot observed at one place at one time.

Area forecasts will sometimes include a cloud top forecast (look for "TOP FL200" or similiar). However, a forecast—especially an area forecast which often covers half a state—is vastly different than an observation.

You've already mentioned Skew-T charts, and they do have useful data. Depending on your application, this might end up being your best bet. If you want something that doesn't have a real world aviation application (e.g. for the SIM community), you could derive your sought information from this.

  • $\begingroup$ You are correct. There is no such API. However, I did find more information in the Earth Science stack exchange after receiving the suggestion by casey in his answer. I'm leaving this question here in this exchange just in case it helps somebody else. I wish I could give the points to both of you. $\endgroup$
    – Patricia
    Jan 28, 2016 at 17:34
  • $\begingroup$ @MissLucy Oh, I don't care about points! Glad you found useful information :) $\endgroup$
    – J W
    Jan 28, 2016 at 19:01

There isn't a simple easy-to-use API for this, but there is a plethora of model data you can use to derive a proxy for cloud locations. Specifically the GFS and ECMWF both run global forecast models and there are various regional models (e.g. in the US we have NAM, RAP, HRRR, ensembles and various high-res WRF runs). The GFS, for example, provides relative humidity and cloud water mixing ratio at its vertical gridpoints and from these you could model where clouds are likely to be.

It is certainly possible to model cloud bases with publicly available datasets as demonstrated by the folks at SunsetWX can attest to, as cloud base heights play a role in vivid colors at sunset.

This won't be an easy-to-query API, but well within the research of someone willing to work with existing forecast and observational data (satellite (visible, IR, water vapor), soundings, profilers, radar, etc) to build a predictive cloud location model. There may already be published literature on this and you might get more information over on Earth Science stack echange if that is the case or if there is some dataset already out there that I'm not personally aware of.

  • $\begingroup$ Thank you, casey, for your suggestion. There is a lot of information on this subject on the Earth Science stack exchange. Unfortunately, as @JohathanWalters says in his answer, there is no such API. I wish I could give the points to both of you. $\endgroup$
    – Patricia
    Jan 28, 2016 at 17:31

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