Isle of Arran climate by month
Warmest month: July (highs about 19°C). Coolest: January (about 8°C). Wettest: January (166 mm). Driest: May (79 mm).
Source: Met Office, Bute: Rothesay, 1991-2020 averages (Open Government Licence v3.0). Daylight is calculated from the latitude of Isle of Arran for the 15th of each month. Arran has no Met Office climate station; the Met Office names Bute: Rothesay, about 30 km to the north, for the geohash of Brodick and of Lochranza. Arran's mountains are wetter and colder than these figures.