In 1906, the mean temperature of England and Wales was 49·3° Fahr., while that of Cornwall was 51·2. The mean temperature of England in 1907 was 48·5, of Cornwall 50·6. But there exists a considerable difference between north and south. At Redruth it was in 1906, 50·1, whereas at Truro it was nine degrees higher.
The east wind prevails in October and is strong in March, the south-east in June, the south-west is felt in every month save April, but very little in December. The west wind is most prevalent in August, least so in May. The north wind predominates in December and July.
The rainfall chart here given shows that Cornwall lies for the most part in an area where from 40 to 60 inches are annually recorded, though a strip of the north coast from St Ives to Padstow and again from Boscastle to the northern limit of the county shows a fall of less than 40 inches. This is because the uplands have robbed the rainclouds of a considerable portion of their contents, and accordingly it is on these high moorlands that we find the greatest rainfall. Thus on the moors between Launceston and Bodmin from 60 to 80 inches fall, and even this latter figure is exceeded in the neighbourhood of Rough Tor and Brown Willy.
From observations taken at the Royal Institution of Cornwall at Truro, from 1850 to 1881 it appears that the rainiest months are November and December, and next to them January and July; April and May are the least rainy.
The original population of Cornwall would seem to have been what is now commonly called Ivernian, the same as Iberian, the underlying race everywhere in Western Europe from the western isles of Scotland to Gibraltar. When the Romans invaded and conquered Spain, they found there already in the east the Celts and in the west the Iberians, and they designated the more or less fused population, Celtiberians. So in Cornwall, there was this dark-haired, dusky-skinned race, and the Brythons, Celts, of the people of the Dumnonii. There were extensive settlements by Irish in the Land's End district, the Lizard, and along the north coast, in 490-510, owing to the expulsion of the Ossorians and the Bairrche from their lands in Ireland. The Saxon also crossed the Tamar and peaceably settled in East Cornwall.