The Midnight Sun circles above the horizon in Spitsbergen from mid-April until late August giving 24-hours of daylight. During June and July the Sun shines quite high up in the sky, making a circle at the same height above the horizon. During August the Sun stays close to the horizon for many hours making long shadows and picturesque light conditions. From late August to September the Sun lights up the mountainsides and mountain tops with yellow hues together with autumn colors. The dark season when the Sun doesn’t rise above the horizon starts already in late October and lasts until mid-February. Continual winter darkness, the Polar Night, lasts from late November until late January. During that period the darkness is almost complete 24-hours and the difference between midday and midnight is impossible to tell. The seasons between the Polar Night and the Midnight Sun are very short; in two months the darkness changes to 24-hour daylight. Life is much about extremes up north in Spitsbergen, whether it is about the light or other natural conditions.
The climate in Spitsbergen is widely affected by the Gulf Stream, which brings warmer water north from the Atlantic. This ocean current splits in two main branches on the northern coast of Norway and the more northerly branch; the western Spitsbergen current follows the west coast of Spitsbergen and continues further to the north-eastern side of the archipelago. On the east coast of Spitsbergen a cold ocean current carries cold arctic water towards the southern Barents Sea. These two currents play a crucial role in the local climate and weather and create a huge difference between the western and eastern sides of Spitsbergen. Western coast and the fjords stay mainly ice free even during the winter whereas the eastern side has ice cover almost 10 months each year. First in late summer it is possible to circumnavigate Spitsbergen without problems with the sea ice. Due to the warm western current polar sea ice edge is further north than anywhere in the world and therefore in Spitsbergen you get furthest north and sometimes well above 80° latitude without using large ice breaker vessels.
Due to the warm western ocean current the climate in Spitsbergen is also considerably milder in winter compared to other places at the same latitude. The yearly average temperature in the largest fjord Isfjorden on the western side of Spitsbergen is around -7,5°C. Temperatures fluctuate widely, especially during the winters, and on the western and mid-regions daily temperatures vary between -5 and -20 in most days the whole winter. Some days with temperatures around zero or even above zero are not very uncommon either, especially not in early winter. In the eastern and northern regions temperatures are normally lower and winds colder. July is the warmest month of the year with average temperature of balmy +6°C. During the summer months temperatures stay above zero around the fjords and near the coast line. Days above +10 degrees are somewhat rare as are days below +2. Days when wearing T-shirts and shorts in Spitsbergen are maybe as rare as snowfall in Dubai. Therefore bring with you a variety of warm clothes and leave the lightest summer layers back home. Indoor temperatures in Longyearbyen on the other hand are pretty high in all buildings, so you might find good use for a T-shirt or light long sleeved while in town.
Amount of precipitation in Spitsbergen is normally very low. Spitsbergen is said to be arctic semi-desert and rainy periods are normally very weak and short lived. During the last years somewhat heavier rain and a bit higher temperatures have been a more common phenomenon. Weather forecasts for Spitsbergen are not very accurate, due to large local variations caused for example by topography, large glaciers and big temperature differences between west and east. Larger scale forecast normally gives pretty reliable idea of the weather for nearest couple of days. Weather can be windy, chilly and cloudy in one fjord and sunny and calm just 20 km away at the same time. Weather tends also to change pretty often and quite fast.