The dry season - the period going from June to January - has very low levels of precipitation and also low levels of humidity. These months are the best time of the year to go to Fortaleza and Cear. See graphs below for details on humidity, precipitation and air temperatures.
Summary of cost of living in Fortaleza, Brazil: A family of four estimated monthly costs are 2,199.9$ (10,724.7R$) without rent. A single person estimated monthly costs are 620.0$ (3,022.5R$) without rent. Fortaleza is 64.7% less expensive than Seattle (without rent).