I do not really understand what you are trying to do with the loc(1):max(loc) bit.
As Elias says, you want | instead of &. But note that you also did not need the find:
Wind_All = [year month day speed];
loc = Wind_All(:, 2) == 1 | Wind_All(:, 2) >= 11;
filtered = Wind_All(loc, :)
And personally, I would use ismember instead of your logical expression: Wind_All = [year month day speed];
loc = ismember(Wind_All(:, 2), [1, 11, 12]);
filtered = Wind_All(loc, :)
Best Answer