Weather is probably a major factor when you plan your trip to Teresina, and keep in mind that cheaper options are usually available when the weather isn't as good. The hottest months are usually September and October with an average temp of 85°F, while the coldest months are June and July with an average of 81°F. The rainiest months in Teresina are March, February, April, and January, with each month seeing an average of 13 inches of rainfall.