IP65 on a datasheet means dust-tight and protected against water jets. It does not describe what happens after two years of coastal salt fog, UV exposure on a black panel, or condensation forming inside a sealed housing.
Salt fog is the coastal test
Salt spray resistance beyond 120 hours is the number to look for, and 200 hours on an aluminium range is better. Coastal installs live or die on the finish, not the electronics.
Condensation is the hidden failure
Temperature swings push moisture through the smallest gap and condense on the cold side of the PCB. Gaskets and conformal coating matter more than the IP number in a temperate climate with cold nights.
What to specify
Salt-spray hours, operating temperature range, and whether the keypad is glass or IMD film. Then ask for the test report, not the marketing line.
Takeaway
IP protects against water jets; the finish and the coating protect against years.