Most Recent Weather in Benidorm in December. December 11, 2017/ By:Admin/ No Comments What’s the weather like in Benidorm in December Temperature December is a very cool month to visit Benidorm,Spain, when the average temperature is just 12°C, making plenty of warm clothing necessary. During this time of year, highs of up to 16°C are the norm, cooling down to 7°C after the sun sets. Average Sea Temperature and Sunshine Hours With an averagesea temperature of 16°C, it might be a bit too cold to spend a day at the beach. Although the resort enjoys seven hours of sunshie each day, there is also 11 rainy days throughout the month, so don’t forget to pack some waterproof clothing for your holiday. Weather in Benidorm in December.