In the Karkonosze Mountains, as in other mountain areas, there is a double layer of climatic zones associated with the dominant influence of altitude. The following four floors are distinguished by:
moderately warm(Below 600 m asl.) with an average temperature of more than 6 ° C, characterized by weakened dynamic activity of the air and strong spatial variations in temperature and precipitation,
moderately coolWith an average temperature of 6 ° - 4 ° C; characterized by a high frequency of fen winds, small heat resources of the growing season and predominantly high precipitation level
cool(960 -1320 m asl.) with an average annual temperature of 4 ° - 2 ° C; characterized by severe thermal conditions, large sums of annual precipitation (above 1200mm) and very favorable conditions for accumulation and retention of snow cover.
very cool(Over 1320m asl.), with an annual temperature below 2 ° C; characterized by outstandingly dynamic activity of the air, low temperature and considerable revenue of water coming from precipitation and atmospheric precipitation.
The altitude ranges of the individual climatic zones in the Karkonosze are relatively lower in relation to the Western Carpathians (by 250-300m.)
Air temperature changes with height above the sea level. In the Karkonosze Mountains its average fall is 0.6 ° C at 100 meters. As a result, the temperatures in Karpacz are 5-6 ° C higher than in Śnieżka and 4-5 degrees higher in Szklarska Poręba than in Szrenica. The warmest month of the year is July (Karpacz about 15 ° C, Snowfall 8.5 ° C), and the coldest January (Karpacz - 2,5 ° C, Śnieżka - 7.8 ° C). On the main ridge of the Giant Mountains the temperature in summer does not exceed 15 ° C.
The precipitation rate is clearly dependent on absolute altitude, for example at the foot of the Giant Mountains it is 950 mm annually, but in the highest parts of these mountains it is over 1400 mm. The heaviest rainfalls occur in July and August, the least in spring months.
Snow remains in Karkonosze usually for 100 days in Karpacz and Szklarska Poręba to 176 days on Śnieżka. In post-glacial boilers, that period expands for longer - often until August.
RimeThe most interesting element of the winter landscape of the Giant Mountains is the rime. It is an ice or snow formation formed either by supercooled water setting and freezing on the surface of trees, columns and buildings of contained, or by resublimation of water vapor. In second case – we do not observe the presence of mist. There are three types of rime:
• Ice rime - formed with the coarsening of freezing rain or drizzle, creates ice crust with developed ice crystals
• hard rime - it is formed by the mist and strong wind, forms various crystalline forms
• soft rime - soft ice crystals, frost-like appearance, created in poor wind and no fog conditions.
In the Karkonosze Mountains it is the hard rime that is usually formed. In the peak zone it occurs from September to May, occasionally recorded during the summer months. The weight of the rims covering the trees or the mountain trail poles is often so great that it causes them to break and deform.
In Karkonosze winds blow mostly from western directions, bringing humid air from the Atlantic, which results in periods of rain lasting usually for couple of days. Warm and dry air masses from the south and south-east (mostly in Autumn) are accompanied by short and violent downpours.
The mountainous areas are characterized by fenny winds - strong, gusty, dry and warm.
The highest speed above mentioned winds reach in the middle of the northern slopes altitude (from 1100 m down), coming not constantly – but “in waves”. They tend to be so strong that may cause numerous damage including trees and tree stands destruction. Interesting phenomenon is the so-called "fen clouds shaft". It is a layer of clouds covering the ridge of the mountains and often accompanied by higher-level, picturesque lenticular clouds. The most intense fen phenomena occur in autumn and spring. In winter, however, more frequent are the temperature inversions. It comes to them when heavier and cooler masses of air flow into the lower parts of the Giant Mountains and to the Jelenia Góra Basin. Then the temperature rises along with the height. It is accompanied by the phenomenon of clouds and mists retention mostly in the lower areas.
The area of the Karkonosze stands out among others by the highest occurrence of mists in Poland (on Śnieżka avg. 306 foggy days) and a large number of cloudy days (on Śnieżka average 178 per year). The raw climate of the Karkonosze, combined with poor soil conditions, has created specific conditions for the existence of plants and animals here, which is reflected in the lowering of all vegetation floors compared to other Central European mountains.