The climate of Bielsko-Biała and Podbeskidzie Region

The climate of Bielsko-Biała and Podbeskidzie Region

The climate conditions of Bielsko-Biała and its surroundings are very differentiated because the area is located in two different climate regions. The climate in this area is obviously dependant on circulation factors (the masses of air from different regions).It results in the instability of the weather and large amplitudes of temperatures during the year. The air masses from Atlantic Ocean have the biggest influence on the formation of the weather in the area of Bielsko and its surroundings. Western and south-western winds are the most frequent in this area.

During winter south-western and southern winds are dominating and, during summer, most of winds blow from west and north -west. Foenhs make some percentage of southern winds (they appear more often during winter months than during summer). They influence the climate both positively: – the relative humidity of the air is lower, – the temperature is higher, – the termal inversions are are diminished, and negatively: – the air pressure changes rapidly. The nebulosity is highest in the area of Bielsko and its surroundings from November to January. In the end of summer and beginning of autumn the average nebulosity is the lowest and the sunny days rate (9 sunny days a month) is the highest.

Thermal relations generally are conditioned by the specific airmasses, however their spatial differentiation is also connected with the sculpture of the earth’s surface. In general, the air temperature lowers (on the average 0oC by 100 meters) accordingly to the rise in altitude. The average temperature level varies from 4oC to 4,5oC (in the ridge parts of Beskidymountains) to 8oC in the area of Bielsko-Biała. In the yearly temperature run the highest level of the average temperature fall in July (about 18oC), in the mountain area (about 13oC). The coldest month is January for which the average temperature level amounts to about -2oC, in the mountains about -5oC. The period without ground frosts lasts in Pogórze, on the average, 175 days. In mountain, this period is over one month shorter. About 40-50 days a year are foggy in Bielsko.

The amount and distribution of precipitation in this area is mostly dependant on wind vectors and the altitude of the area and its exposition in realtion to these vectors. The area with the highest rainfal (over 1200 mm yearly) is Beskid Śląski. The highest monthly rainfall amounts are noticed in July, and the lowest in September ond October. In the area of Bielsko, snowfalls occur from November to April. The month with the highest snowfall amount is January.

The snow cover varies very much, as the result of the fact thatthe administrative borders of the city comprise a part of BeskidŚląśki (slopes of Szyndzielnia, Klimczok and Dębowiec) and a part of Beskid Mały (a mountain range of Magurka Wilkowicka). Yearly amount of the days with a snow cover oscillates from about 70, in the lowest nothern part, to over 200 in the top parts of Beskidy. In general, 10 more days with snow cover fall to every 100 meters rise in altitude. Maximum snowcover thickness in Bielsko-Biała (55 cm) was noticed in sixties.

Based on: R.Gerlach, Master’s Thesis, 1999,PM/99/024/KK, Department of Climathology, Silesian University, Sosnowiec