Climate in Lahijan

The precipitation regime shows a sharp maximum in autumn (September to December), when atmospheric instability is at its highest point, medium values in winter and early spring, and lowest values from May to August.

Mean annual rainfall varies between 1200 and 1800 mm along the shoreline, decreases towards a sub-humid area in the southwestern corner of the, and reaches again very high amounts in the lower part of the mountain, up to 1500–1800 m. Along the Safid-rud valley, swept every afternoon in summer by the violent northerly Manjil wind (Tholozan), a very rapid transition leads to the Mediterranean-like semi-arid area of Rudbar and Manjil.

The climatic privilege of Gilan explains its luxuriant natural vegetation.

According to altitude, three forest levels can be distinguished: the Hyrcanian mixed forests, the mountain beech forest, and the High Mountain oak and hornbeam forest. The Hyrcanian forest strictosensu once covered the plains, where only residual patches remain on coarse alluvial terraces between cultivated areas, and still covers the greater part of the first slopes of the mountains up to about 1000 m.

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