The Krkonoše Mts. are situated in a mild climatic zone which, beside the seasonal change, are impacted by the Atlantic Ocean and predominating western winds which cause the erratic character of the weather. In comparison with the Slovak mountains, the Krkonoše Mts. have an oceanic character of weather and are the mountains with the roughest climatic conditions in all the Czech mountain ranges. This is an influence of the elevation of its ridges being permanently exposed to the wet oceanic air. Weather was and has been reflected in the entire natural process, in the vegetation composition, in altitudinal zonation and finally with a principal impact on every tourist coming to the Krkonoše Mts. The average annual temperature in the Krkonoše Mts. is somewhere between 6 o and 0 oC (the coolest weather is on top of Sněžka 0.2 oC, a little bit higher is the temperature at the upper stations by Labská bouda and by the Szrenica chalet at 1.9 oC) while the valley positions are essentialy warmer (Žacléř 6.1 oC, Karpacz 5.9 oC, Szklarska Poreba 5.8 oC, Harrachov 4.9 oC, Špindlerův Mlýn 4.7 oC). It is generally valid that the higher the elevation the lower the air temperature, and that each 100 meters of elevation generates a difference of about 0.5-1.0 oC. Sometimes the situation of so called termic inversion occurs when it is sunshiny and warm in higher positions while the valleys have cold temperatures and moisture in an air mass is condensed into fog. Such inversions are very frequent in the Krkonoše Mts., especially in autumn and winter months when it can last days, and rarely even weeks. The emission load of locations in valleys is then rather large in comparison to the ridges where the air is relatively clean. Sometimes inversions oCcur when fog fills in the whole Česká kotlina and only the highest peaks of the Krkonoše Mts., Jizerské hory and Jeseníky rise as islands from the "white ocean".
The warmest temperatures in the Krkonoše Mts. occur in July (average temperatures from 14 oC in lower elevations to 8.3 oC on Sněžka), and on the contrary the average coolest temperatures are in January (from -4.5 oC to -7.2 oC on Sněžka).
Precipitation is bigger with a higher elevation, and ranges from about 800 mm which falls on the foothills of the Krkonoše Mts. annually to 1200-1600 mm on the ridges. The Krkonoše Mts. are among our mountain ranges with the richest rainfall activity. You can see the division of rainfall during a year from the climate chart. Exceptionally there are rainfalls of a calamitous or disasterous character in the Krkonoše Mts. because they evoke flash floods. 100-200 and more mm daily can fall in such situations (e.g. Obří důl 29. 07. 1897 - 266 mm).