Regardless of the time of day you decide to fly, the ticket price will remain around the same. Book flights from Oakland, California to Barranquilla as you normally would.
Due to multiple factors, expect to potentially pay more when booking in December. For low rates, May can be a great choice for travel to Barranquilla. Flights to Barranquilla from Oakland, California in May are about $707 on average during May, but can be found for as low as $508.