Myrtle Island Beach Custom Search   At Myrtle Island Beach through the summertime months highs are in the 80's with overnight lows in the 60's. The cold days of the wintertime come with highs in the 40's, and winter nights come with lows in the 20's to Myrtle Island Beach. From a rain point of view Myrtle Island Beach is a reasonably common site. The wettest month of the year is mostly March, that's the one that rains the most, and the driest month is October.     Map Detailed Map Weather Local weather forecast These outdoors activities are available near Myrtle Island Beach.