Planning a trip in early June. What temperature and rain can I expect? Would mid-May be better?

Hi, the average temperature then could be about 23-25 C. Sometimes, it rains a lot. So apart from the short-sleeved and the long-sleeved shirt, you also need take along the rainy wear in case of the rain.
Anyway, to pay much attention to the weatehr report is suggested.
During the mid-May, it could be cool, with the average temperature of 20 C. It can be good traveling then.