Regardless of the time of day you decide to fly, the ticket price will remain around the same. Book flights from Phoenix to Namibia as you normally would.
In terms of precipitation, rainfall in Namibia ranges from 0.0 - 3.1 inches per month. February is typically the wettest month, when rainfall can reach 3.1 in. May is typically the driest time to visit Namibia when rainfall is around 0.0 in.
If weather is an important factor for your trip to Namibia, 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 77.0 F. Travelers looking to avoid the cold should look outside of June, when temperatures are typically at their lowest (around 55.4 F).