Mangroves occupy a modest area in the coastal provinces from Quang Ninh to Ha Tinh, they however have important signficances in terms of ecology as well as of protecting man-made values. Mangrove reforestation and afforestation, the necessaries for sustainable development in these areas, require mam conditions including climatic ones. An assessment of climatic advantages and disadvantages for mangrove development in Quang Ninh - Ha Tinh coastal zone is herein presented on the following bases: current situation of mangroves, analyses of climate data from local meteorological stations, analyses of bio-climatic conditions and ecological thresholds. As a result of this, entire coastal zone from Quang Ninh to Ha Tinh has an ombrothermic regime, in which basically mangroves can develop, however only two places, the North Quang Ninh and Ha Tinh, have optimal rainy and humid conditions for mangrove. Common adverse impottsof climate on mangrove are large annual temperature range, destruction of tropical depression or storm. Entire zone can be bioclimatically divided into three following areas with the disadvantages for mangroves: Quang Ninh - Hai Phong with cold weather conditions and frost
Thai Binh - Ninh Binh with arid, cold, hot conditions but in moderate graveness
Thanh Hoa - Ha Tinh with hot weather and also arid condition added to its northern part, Thanh Hoa - Nghe An.