Weather will likely play an important role when you plan your trip to Cajazeiras do Piauí, but bear in mind that cheaper options are usually available when the weather isn't as good. The hottest months are usually October and September, with an average temperature of 30°C, while the coldest months are July and March, with an average of 27°C. The rainiest months in Cajazeiras do Piauí are March, February, January and April, with each month seeing an average of 177 mm of rainfall.