The best time to fly to Rosario is during , but great deals can be found at other times. January tends to be the warmest period in Rosario so if you are looking for sun or warmer climates then look to fly around this time. March is the wettest if you need to factor this in to your plans.
What time of day is cheapest to fly?
At the moment, there are flights only in the morning for your Rosario trip.