I need to make use of Mathematica's WeatherData functionality, the CloudCoverFraction property, specifically. However, it does not seem to work. I need to know this fraction for New York City on, let's say, 1 December 2013, so I entered the command clouds = WeatherData["New York", "CloudCoverFraction", {2013, 12, 1}]. The result was a time series with 36 data points - but when I tried to retrieve the values with clouds["Values"], I only got {Missing["NotAvailable"],..., Missing["NotAvailable"]}. The result is similar when I try e.g. London. Is this a bug or I'm doing a mistake somewhere?

  • $\begingroup$ Same result here. These data seems indeed to be not available (but for example it works if you replace CloudCoverFraction with Pressure). $\endgroup$ – SquareOne Dec 18 '14 at 9:50
  • $\begingroup$ However if you ask WolframAlpha WolframAlpha["new york cloud cover december 1 2013", "ComputableData"] it seems to be available. $\endgroup$ – SquareOne Dec 18 '14 at 10:06
  • $\begingroup$ @SquareOne, the WolframAlpha query works (which I didn't know) but the problem is that I need the values for approx. 600 days (consecutive) as I'm studying effects of weather on some other phenomena. I guess I would have to run the query for every single day...? $\endgroup$ – Skumin Dec 18 '14 at 10:27
  • $\begingroup$ It seems that with WolframAlpha you cannot get more than one month of data at once, for example WolframAlpha["new york cloud cover december 2013", "ComputableData"]. So for a whole year you'll just have to call that 12 times by changing the name of the month of course. Then of course you'll have to group all the data ... $\endgroup$ – SquareOne Dec 18 '14 at 11:23
  • $\begingroup$ If you go back to 2009 or earlier, you get numbers for cloud cover. Perhaps it is related to the dates of the sources here: reference.wolfram.com/language/note/…. It suggests that recent weather data is not included in the curated WeatherData. Seems odd to me, since some recent data is available. $\endgroup$ – Michael E2 Dec 18 '14 at 14:25

I get 34 data points of which 6 are not Missing:

clouds = WeatherData["New York", "CloudCoverFraction", {2013, 12, 1}]

clouds["Values"] // DeleteMissing
(* {1, 1, 1, 0.75, 0.75, 0.75, 0.75, 0.75} *)

DateListPlot[DeleteCases[clouds["Paths"], {_, _Missing}, {2}], 
 PlotStyle -> PointSize -> 0.02, Joined -> False]

Mathematica graphics

You might want to prefer using DeleteMissing[clouds["Paths"], 2] instead of the DeleteCases above if you have v10.0 or higher.


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.