Upcott Lane, Bideford
It is largely the shelter given to it by Dartmoor and the Blackdown Hills that makes the south and south-east of Devonshire so famous for its warm and pleasant climate. The south-west also benefits from the protection afforded by the spurs of Dartmoor, but the rainfall of that district is heavier and the air more relaxing.
The prevailing winds in Devonshire are the west and south-west, which, blowing across the open Atlantic, are also the chief rain-carrying winds. Both are comparatively warm, the latter following the course of the Gulf Stream. But they are often violent, and vegetation fully exposed to them does not flourish.
The peninsula of which Devonshire forms a part contains the warmest districts in Great Britain. The annual average temperature of the whole county is 49 ½° Fahr., which is a degree and a half higher than that of the whole of England; while the average for Torquay is 51°. In the three winter months, January, February, and March, in which the average temperature for London is 39·7°, that for Torquay is 41·3°.
The annual amount of bright sunshine in Devonshire naturally varies in different years. In 1906 it was nearly 2000 hours on the south coast, and not less than 1800 on the north. The average amount appears, however, to be about 1700 in the south, and 1500 on the north coast, or between three and four hours a day. The actual amount would, of course, be much more than this in summer, and much less in the winter.
The amount of rain in Devonshire in 1907, which was an average year throughout the country, was (taking the mean of the 169 stations named in Dr H. R. Mill's British Rainfall) 41·24 inches, falling on 210 days, or about 7 ½ inches and 7 days above the average for the whole of England and Wales. In the same year 196.16 inches of rain were registered at the Llyn Llydaw Copper Mine near Snowdon, and only 16·6 inches at Clacton-on-Sea. The wettest part of the county is Dartmoor, which catches the moisture-laden clouds coming up from the Atlantic. In 1907 some 81 inches of rain fell at Princetown, at a spot 1390 feet above the sea. This amount was, however, much exceeded in 1903, when the rainfall at the same station was 102·32 inches, and in Cowsic Valley, a little lower down, it was half an inch more. The driest part of Devonshire is the south-east coast. In 1907 only 26·27 inches of rain fell at Exmouth, for example. Heavy as the rainfall is, the slopes of the land are so steep and the soil in general so porous that the water soon runs away, with the result that both the earth and the air are drier than might be expected.
A feature of Dartmoor even more striking and characteristic than its heavy rainfall is the fog which so frequently covers it, and which is sometimes so dense as to cause the most experienced moor-men to lose their way.
Speaking generally, the climate of Devonshire may be described as warm and moist and remarkably equable. The winters are very mild, and snow is rare, except on Dartmoor. On the south coast of the county many plants which in less favoured parts of England need protection in the winter, such, for instance, as geraniums, hydrangeas, heliotropes, and camellias, are left out-of-doors all the year. Magnolias reach to the tops of the houses, myrtles grow to a height of thirty feet or more, palms and eucalyptus flourish, and oranges, lemons, and citrons do well in the open air.
Devonshire seems peculiarly liable to seismic disturbances, and many slight shocks of earthquake have been recorded.