Thinking of coming out for a couple of weeks from the 19 January, what will the weather be like?

I have been in January for the past 6 years and mostly had very good weather, a lot of warm sun (shorts and tee shirt),the occasional wet day and a few cloudy but quite warm days.
Cold enough at night for a sweater or jacket, but never the need for an overcoat and scarf as you would need at home.