Should one go poleward or even toward a polar sea , one finds that the warmest month has an average temperature of less than NUMBER@1 ° C -LRB- NUMBER@2 ° F -RRB- , and the subarctic climate grades into a tundra climate even less suitable for trees .

Poleward or even approaching polar seas , the warmest month has an average temperature of less than NUMBER@1 ° C -LRB- NUMBER@2 ° F -RRB- , and the subarctic climate grades into a tundra climate even less suitable for trees .
