You can store each sample in two byte assuming that your wind speed values are not higher than 255 and you are happy with direction to the nearest 2 degrees (your measurements are unlikely to be more accurate then this anyway).
So 20 sample per minute for ten minutes is 400 bytes of RAM, leaving plenty for the rest of your code.
You can have an array values as follows:
byte speed[200];
byte direction[200];
and use a counter to fill up the array. if the counter starts at 0 then when it gets to 199 you can send the data to your computer and reset the counter to start over.
Not sure if matters, but yes, you are still programming in the C languge (actually its a subset of C++) when using libraries.