The relatively low height of most of the fells means that, while snow is expected during the winter, they can be free of snow at any time of the year. Normally, significant snow fall only occurs between November and April. On average, snow falls on Helvellyn 67 days per year. During the year, valleys typically experience 20 days with snow falling, a further 200 wet days, and 145 dry days. Hill fog is common at any time of year, and the fells average only around 2.5 hours of sunshine per day, increasing to around 4.1 hours per day on the coastal plains.