The two other answers are a more correct way of doing it. There is no need to create this many variables in your workspace. However, if you must...
You should use a structure instead of individual variables.
Blank_Vec = zeros(6964,1);
Num_Cols = 60;
for ii = 1:Num_Cols
name = sprintf('lat_%i_days',ii);
ZeroColStruct.(name) = Blank_Vec;
if you absolutely MUST have individual variables, one method is this: