Hemiboreal means halfway between the temperate and subarctic (or boreal) zones. The term is most frequently used in the context of ecosystems.

A hemiboreal forest will have some of the characteristics of a boreal forest, and also share some of the features of the temperate-zone forests to the south. Coniferous trees predominate in the hemiboreal zone, but a significant number of deciduous species will be found there as well.

The term is also sometimes used to denote the form of climate that is characteristic of the zone of hemiboreal forests — specifically, the climates designated Dfb, Dwb and Dsb in the Köppen climate classification scheme. On occasion, it is applied to all areas that have cold winters and long, warm (but not hot) summers — including those which are semiarid and arid based on average annual precipitation.

Examples of locations where the climate and/or ecosystem is classified as hemiboreal include much of southern Canada, the states of Maine, New Hampshire and Vermont, and the northern parts of the states of New York, Michigan, Wisconsin and Minnesota, along with eastern North Dakota, within the United States, and in Eurasia, central Scandinavia, eastern Poland, all Belarus and most of Ukraine, plus a wide swath of Russia, extending eastward into the southern parts of Siberia and the Russian Far East.