I think this is a little bit outdated at least for the Philippines. Goverment documents now primarily use A4 to comply with ISO standards. Some places such as schools may sometimes use the letter size (commonly referred to as short size here) but A4 is now much more common.

The other day, a place in the Philippines recorded a Heat Index of around 58 degrees Celsius (136 F). That is classified as Extreme Danger and most places have heat index a little bit lower than that.