Regardless of the time of day you decide to fly, the ticket price will remain around the same. Book flights from Valparaiso, Florida to Oslo as you normally would.
In terms of precipitation, rainfall in Oslo ranges from 1.6 - 3.5 inches per month. August is typically the wettest month, when rainfall can reach 3.5 in. February is typically the driest time to visit Oslo when rainfall is around 1.6 in.
If weather is an important factor for your trip to Oslo, use this chart to help with planning. For those seeking warmer temperatures, July is the ideal time of year to visit, when temperatures reach an average of 62.6 F. Travelers looking to avoid the cold should look outside of January, when temperatures are typically at their lowest (around 26.6 F).