We already pointed you to https://www.mathworks.com/matlabcentral/answers/1793805-how-can-i-get-precipitation-data-only-for-summer-june-august-for-30-years?s_tid=srchtitle
If you need to, adjust there is ismember() the month column against the appropriate representation of the months you are interested in.
ismember(t.Month,{'June','July'})
for example.