Lists of mountains and hills in the British Isles in England, 366 in Wales and 11 in the Channel Islands. A Simm is a mountain the British Isles that is over high and has a prominence of at least . The word comes from Six-hundred Metre Mountain. There are currently 2,754 recorded Simms in the British Isles, including 2,188 Scottish Simms, 192 English Simms, 149 Welsh Simms, 1 Isle of Man Simm, and 224 Irish Simms. By definition, all Simms are also TuMPs (see below) and most, if not all, are mountains, depending on whether 600 metres or 2,000 feet (610 m) (e.g. a ), is used as the
Climate of the British Isles persist for hours or even days in the winter and can pose a major hazard for drivers and aircraft. Fog is more common inland and on higher altitudes; mainly during winter and during the morning at times of high pressure. On occasions blocking anticyclones (high pressure systems) may move over the British Isles, which can persist for weeks or even months. The subsided, dry air often results in clear skies and few clouds, bringing frosty nights in winter and hot days in the summer, when some coastal areas can achieve almost maximum possible sunshine for periods of weeks. Rainfall varies