Regardless of the time of day you decide to fly, the ticket price will remain around the same. Book flights from Dallas to Curitiba as you normally would.
In terms of precipitation, rainfall in Curitiba ranges from 3.1 - 11.8 inches per month. May is typically the wettest month, when rainfall can reach 11.8 in. January is typically the driest time to visit Curitiba when rainfall is around 3.1 in.
If weather is an important factor for your trip to Curitiba, use this chart to help with planning. For those seeking warmer temperatures, January is the ideal time of year to visit, when temperatures reach an average of 78.8 F. Travelers looking to avoid the cold should look outside of June, when temperatures are typically at their lowest (around 71.6 F).