I would suggest creating the title like this:
months = {'Jan', 'Feb', ...};
years = num2str((1979:2018)');
for i = 1:40
for k = 1:12
title(strcat(months{k}," ",years(i,:)));
end
strcat is a string concatenation -> It puts the strings together. I assumed the outer loop is meant to be years so I changed it from 12 to 40 since you mentioned 40 years.
-Also note, it is highly recommended that you do not use i as a variable. It is the built in constant for the imaginary number.
