Weather Facts: Frost hollow | weatheronline.co.uk Frost hollows are widespread along the Welsh borders or Scottish glens. A frost pocket may also occur behind a wall or hedge. In the case of the famous Rickmansworth (Herts.) frost pocket, a railway embankment prevents the natural drainage of cold air from the valley The Hertfordshire town also has a significant downside, however: its microclimate. Rickmansworth lies in a “frost pocket” — which means it is often up to 10C colder than surrounding areas and holds the British record for the biggest temperature swing in a single day — from a low of 1.1C one August night to a high of 24.9C the following day. Blowing hot and cold | The Sunday Times
