The main race in Cork this weekend is of course the Bay Run half-marathon in west Cork.
It looks like the weather may be ok for this race with a north-westerly wind behind the runners from Glengarriff to Bantry. The current forecast is that "Sunday will be a cool, breezy day with sunny spells and scattered showers. Highest temperatures of 11 to 14 degrees with moderate to fresh west to northwest winds".
Note that this race is pre-entry only.
Outside of Cork, there are 5 other races and fun runs in Kerry, Clare, Tipperary and Kilkenny. More details on the Running in Munster website.