Temperatures on the southern part of the ice cap are almost always below zero in winter and can reach -20 °C or -30 °C. High winds and storms are common, and therefore wind-chill has to be taken into account as the wind can have a substantial effect on outdoor comfort, even when the ambient temperature is relatively high. Further north beyond the ice cap, annual precipitation decreases. North-east of the ice cap it drops to between 350 and 450 mm per year, the lowest in Iceland. Precipitation increases closer to the north coast and in parts of the highlands such as at Askja. Temperatures can fall quite low in clear and calm weather during winter. Southerly winds generally mean little or no precipitation in the north, along with higher temperatures. Northerly winds bring clouds, with cool and possibly wet weather in the north of the country, while the south is brighter and milder. The same applies to westerly or south westerly winds, which bring warmer weather in the east. The reverse is true of easterly winds, which bring coolness and precipitation in the east and dry, better weather in the west of Iceland. This is the result of the phenomenon of foehn wind. Humid, rather cool air rises as it nears the highlands; condensation then falls in the highlands as rain while warmer, drier air flows down to lower ground on the other side. The difference in temperature can be 10 °C or greater. Vatnajökull National Park is divided into four territories, each of them locally managed. The Northern Territory consists of north-western Vatnajökull, Askja caldera and its surroundings, Jökulsárgljúfur canyon and some of Jökulsá á Fjöllum riverbed. A visitor centre and a campsite are located in Ásbyrgi, along with a campsite in Vesturdalur. The Eastern Territory includes Kverkfjöll mountains and north-eastern Vatnajökull, as well as the expanses of Snæfellsöræfi. A visitor centre is located at Skriðuklaustur. The Southern Territory extends throughout the south-eastern part of Vatnajökull, or from Lómagnúpur mountain in the west to Lón and Lónsöræfi in the east.