Cinque Terre is located in North-West Italy along the Mediterranean Sea. It will be no surprise that the climate is Mediterranean. Hot summers are moderated by the proximity of the sea, while winters are milder due to the fact the coastline is protected from northern winds by the Apuan Alps.
If you go to Cinque Terre for walking, May / June and September / October are the best months.
The table below shows average temperatures (day and night) for the province of La Spezia.