How many parts of Ireland ever receive less than 20cm of rain in a year? Grass fires are not considered a significant danger in CA... it's the big canyon fires

How many parts of Ireland ever receive less than 20cm of rain in a year? Grass fires are not considered a significant danger in CA... it's the big canyon fires with 20+deg slopes rising 1000m covered with Eucalyptus and other large trees interspersed with scrub brush that create firestorms and can easily burn 40km^2 per day even with mild winds.