Just pointing out a relevant post: Modeling wind speed distributions with machine learning

I’m running Mathematica version 10.4 on my desktop and your code runs on my desktop only if modified:

MaxWindSpeedRemoveQuantityDistribution[lat_, long_] := 
   UnitConvert[
      Quantity[
         Part[maxwind/.
            NSolve[
               Probability[x>=maxwind,
                  x\[Distributed]
                     With[{dist=EstimatedDistribution[
                        WeatherData[{lat, long}, "MaxWindSpeed", {{1990}, {2015}, "Year"}],
                        GumbelDistribution[\[Alpha], \[Beta]]]},
                           Switch[
                              dist, GumbelDistribution[_, _],
                              dist, QuantityDistribution[GumbelDistribution[_, _], _], First[dist]]]]==0.02,
               maxwind, Reals]][[1]],
         "Kilometers"/"Hours"]*1.66,
      "Meters"/"Seconds"];

Update 4/17/2016

I’ve verified that this code also works in the Wolfram Cloud, see below.

Deploy modified function:

CloudDeploy[
   FormFunction[{
      "lat" -> Restricted["Number", {-90, 90}],
      "long" -> Restricted["Number", {-180, 180}] }, 
      MaxWindSpeedRemoveQuantityDistribution[#lat, #long] & ], 
   FileNameJoin[{$CloudRootDirectory, "MaxWindSpeedRemoveQuantityDistribution"} ] ]

Open FormFunction in browser and enter latitude and longitude:

And here’s the FormFunction output:

This will give you the desired FormPage behavior:

CloudDeploy[
   FormPage[ {
      "lat" -> <|"Interpreter" -> Restricted["Number", {-90, 90}], "AutoSubmitting" -> False|>,
      "long" -> <|"Interpreter" -> Restricted["Number", {-180, 180}], "AutoSubmitting" -> False|> },
      MaxWindSpeedRemoveQuantityDistribution[#lat, #long] & ],
   FileNameJoin[{$CloudRootDirectory, "MaxWindSpeedAutoSubmittingFalse"} ] ]

For details, see FormObject documentation.