Insular climates are almost invariably milder than those of continents, or even those of the inland regions of large islands, in the same latitudes, and the climate of Orkney is no exception to this rule. Like so many other things Orcadian, the climate is conditioned by the proximity of the sea, and in this case by a sea whose waters are considerably warmer than their latitude might lead one to suspect. The warm surface drift of the North Atlantic is of itself sufficient to explain the relatively mild winter of Orkney, and the presence of the widest portion of the North Sea on the eastern side of the Islands has also a modifying influence. It must also be borne in mind that in cool climates rain brings heat. Our westerly and south-westerly winds, passing over sun-bathed seas, collect in their courses the vapour of warmer climates, and when this vapour, coming into contact with the cooler air of more northerly latitudes, is again condensed into water, a certain amount of the heat thus collected is set free, and raises the temperature of the air, of the rain itself, and of the land on which it falls.

Tabular Statement of Orkney Weather.

It will thus be seen that the mean annual temperature of Orkney is 45.4°, which compares with 46.3° at Aberdeen and at Alnwick in Northumberland, and with 49.4° at Kew Observatory. The total range of temperature is only about 16°, as against 20° at Thurso, just across the Pentland Firth, 22° at Leith, and 25° at London. In this respect the Islands resemble the S.W. coast of England and the W. coast of Ireland. The lowest temperature recorded in Orkney in the eighty-seven years during which meteorological observations have been made was 8°, which occurred on 18th January 1881, the highest was 76°, on 16th July 1876. The temperature of the ocean varies only about 13° during the year, from 41.6° in February, to 54.5° in August. The mean annual rainfall of about 37 inches compares with over 80 inches in many parts of the West Highlands, and with 23 inches at Cromarty, the driest station in Scotland. The wettest months are October, November, and December, during which the Islands receive from one-third to one-half of their annual rainfall, the driest months are April, May, and June, which together receive only one-eighth of the total fall. Thus Orkney is practically never troubled with excessive rainfall, and serious droughts are equally unknown. The mean annual sunshine of 1185 hours compares favourably with 1164 hours at Edinburgh. London enjoys 1260 hours, Hastings 1780. Orkney’s brightest month is May, with an average of 178 hours of sunshine, the gloomiest is December with 20.6 hours.

Apart from the fact that Orkney enjoys the mildest winter of any Scottish county, the chief difference between the weather of the archipelago and that of Scotland in general is perhaps the greater prevalence of high winds in the Islands, which owing to the general lowness of the land receive the full force of the North Atlantic gales, and which moreover lie in the most common track of the Atlantic cyclones, a circumstance which leads to great variability of wind and weather. Orkney has record of only one hurricane, on 17th November, 1893, with a velocity of 96 miles. Several winter gales of over 80 miles have been recorded, and one summer gale of 75 miles in the year 1890. During the fifteen years 1890-1904, 300 gales were recorded in Orkney, practically the same as at Fleetwood in Lancashire, while Alnwick experienced only 157, and Valentia on the west coast of Ireland only 130. Atlantic cyclones are the dominating factor in Orkney weather during the greater portion of the year, producing gales of greater or smaller magnitude, and being almost invariably accompanied by rain, with sudden changes both in the direction and the force of the wind. In the spring season, however, anticyclones frequently cause spells of dry, cold weather, with fairly steady winds from the eastward or northward.

Winter in Orkney is in general a steady series of high winds, heavy rains, and ever varying storms, with much less frequent falls of snow, and fewer severe or continuous frosts than elsewhere in Scotland. Under the shelter of garden walls we have seen strawberry plants in blossom at Christmas and roses in January, while chance primroses may be found in sheltered nooks in any month of the year. The spring is cold and late, but the prevailing winds from N.W., N.E., or E. have not the piercing coldness so often felt in the spring winds along the east coast of Scotland. The summer is short, but remarkable for rapidity of growth. Fogs are fairly common during summer and early autumn, and come on and disperse with exceptional suddenness. Thunder in Orkney occurs mostly in winter, during high winds and continuous falls of rain or snow. The heaviest rains and the most prevalent and strongest winds are from the S.W. and S.E.

Means of Observation in Orkney For Thirty-three Years—1873-1905