The annual number of hours with low sun is highest at 60-70 degrees latitude, making the scope for horizon screening effects particularly wide there. The present paper presents a technique for spatially continuous mapping of local screening effects. The method requires a digital topographical map, and radiation data from a site with free horizon. Screening effects are found to introduce local spatial variations in the solar radiation field, amounting to a factor of more than two within a 10 x 10 km area around Bergen (69 degrees 24＇N, 5 degrees 19＇E).