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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?

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  • $\begingroup$ 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
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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.

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