Due to multiple factors, expect to potentially pay more when booking in December. For low rates, August can be a great choice for travel to Mombasa. Flights to Mombasa from New York LaGuardia Airport in August are about $1,209 on average during August, but can be found for as low as $721.
Regardless of the time of day you decide to fly, the ticket price will remain around the same. Book flights from New York LaGuardia Airport to Mombasa as you normally would.