The best month to visit Reykjavik for ideal weather is during the summer months from June to August when Iceland is at its warmest. Rain and intense winds can happen and with more than 20 hours of sunlight, you will not see the aurora borealis. If you want to see whales, dolphins, humpbacks, and minkes, the best months are from June to July. If you are lucky, you can see blue whales in the summer.  The greatest chance to view the aurora borealis is during the winter months from November to March. You might have to deal with frequent rain, long nights, and cold temperatures which may make your trip worth it. During the fall months from September to October, room rates may drop significantly and tourist areas are less crowded as the summer crowd would have left.  The spring months of April and May would still see some snow and with temperatures rising while the days become longer, the prices for flights and accommodation may not be so high which makes this an ideal time to travel minus the crowds.