The region lies in the temperate zone, and it is characterised by the climatic features of the Carpathian lands. Its position in the range of the Eastern Charpatians, the features of the terrain, the solar radiation and the atmospheric pressure determine the climate of the region.
The Călimani and the Ghiurghiului mountains, the Harghita mountains catch the cold, pluvious air streams coming from the west and from the northwest, so the yearly average quantity of precipitation in the Hășmaș and Giurgeului mountains is less than in the regions lying west.
The Ceahlău massif in the east and the Tarcău mountains in the southeast also influences the climate of the region, because they hinder the Siberian, cold, dry wind, which is called the Crivăț.The intensity of these airflows can be percebtible only on higher peaks and ridges. The temperature inversion is a frequent phenomenon, the cold, greasy air streams are caught in the valleys and the temperature falls below -20, -25 celsius degrees, while in the higher ridges it hardly reaches the -5, -10 celsius degrees. This phenomenon can be observed at the Păngărațului pass, when the Giurgeului basin enshroud in mist, like a rolling sea of fog, from which high peaks show up. The temperature and pressure differential between the peaks and valleys causes upslope and valley winds(mainly in summer). On the influence of these winds the fog disperses in the valleys.
The precipitation is the most frequent in spring, and at the beginning of summer, the yearly average is 800-900 mm. Dry, sunny autumns are characteristic (end of september-beginning of october), when the seeing conditions are excellent , also further lands can be seen excellently. The first frosts set in at the end of september, and they can last even to may; the thickness of the snow-cover can reach 1 metre.
The yearly average temperature in the region varies from 8 to 9 centigrade degree. In summer the temperature can rise to 25 centigrade degrees. In the eastren part of the Bicaz gorge the climate is milder, the presence of mixed forests proves this fact. It is also characteristic the unexpected summer showers and storms, which can be followed by strong lightnings. Storm-winds are less oft, but they occur again at times.
Source: Pál T. - Rab J. - Wild F. - Csíki K. kéziratai.