 Streams passing through caves on the Mendip Hills, including Thrupe Lane Swallet and Viaduct Sink (approximately east of the city), emerge at Saint Andrew's Well in the garden of the Bishop's Palace, from where the water fills the moat around the Palace and then flows into Keward Brook, which carries it for approximately a mile west to the point where the brook joins the River Sheppey in the village of Coxley.Along with the rest of South West England, the Mendip Hills have a temperate climate which is generally wetter and milder than the rest of England.The annual mean temperature is about 10 °C (50 °F) with seasonal and diurnal variations, but due to the modifying effect of the sea, the range is less than in most other parts of the United Kingdom.