If you prefer to explore when it's not as busy, book your stay for December. You could score some good deals on Carndonagh hotels with a kitchenette around that time. The warmest weather is in July, with temperatures ranging from 55ºF (13ºC) to 59ºF (15ºC). It's typically coolest in January, averaging between 41ºF (5ºC) and 45ºF (7ºC).