Climate & Temperature > Spain > Tarragona. The Tarragona temperatures in the February winter month fall in the region of a minimum of 5.1 and a maximum of 15.0 degrees on average. After winter comes spring and the Tarragona climate warms with mean temperatures in May in the range of 11.9 to 21.5 degrees celcius. In August the summertime Tarragona temperature range is from an average low of 19.3 degrees to an average high of 28.8 degrees celcius.