May marks the transitional month between spring and summer. The temperature is much higher, with a maximum temperature of 26 °C (79 °F) and a minimum temperature of 16 °C (61 °F). It is warm during the day and cool at night. A T-shirt and a light jacket are enough for the weather. Ultraviolet radiation is a little stronger, so use sunscreen with SPF 12-15 and PA+ to protect your skin.
May falls during the peak travel season. At this time, hotel rates are often higher than usual and tourist attractions are crowded. If you plan to visit Nanjing during this period, book in advance.