The warm winter has led some trees and flowers to bloom early, up to a month earlier than they did 50 years ago, according to a report in wildlife news website Nature Today.

Between 1940 and 1959, the average temperature in January and February was 2.1° but that has now risen to 5.4°, the researchers say. The current winter is so far the sixth warmest on record.

For example, the deciduous shrub Cornelian cherry used to produce its tiny yellow flowers around March 13, but recently it has been flowering in early February. Snowdrops and crocuses are also now in full bloom, when they used to come out at the end of the month.

The fact that the ash and hazel are producing catkins earlier than normal may also be an issue for hay fever patients, particularly on dry days, because of the concentration of pollen in the air.