When travelling, it's generally smart to pack in preparation for rain or any other conditions that may arise. The rainfall in Newquay is roughly greater than that of Incheon. You can assume this to be the case over the next 22 days.
Temperatures around the 29 °Cs can be experienced in August. The weather in Incheon is hotter than in Newquay. Plan for potential changes in flight availability as peak weather approaches in this location.