Winter is officially over. Some, of course, would think this announcement premature; such as astronomers, who put the birth of spring at the vernal equinox in two or three weeks' time; others live in an ancien regime which would have the season start a month ago. But March and spring are perennial twins to meteorologists, and were born again some days ago.
March, as a rule, is a rough and rowdy month, unsure of itself, and full of bluff and bluster. At times it may regress, reverting to its wintry origins, yet now and then its lengthening days show promise, and hint at better times to come.
Because of its boisterous winds, the ancient Saxons called it 'rough month', Hreth-monath; to the revolutionary French it was Ventose, 'the windy one'; we call it after Mars, the Roman god of war.
If March this year were to behave according to the norm, it would see Ireland for much of the time under the influence of a regular procession of vigorous depressions, each following the other across the Atlantic at intervals of 36 hours or so.
Their energy comes from the contrast in temperature between the equator and the poles, a contrast that is near a maximum at this time of the year. But these breezy conditions keep the fogs at bay, which perhaps is just as well, since an old saying tells us:
So many fogs in March you see,
So many frosts in May will be.
Yet despite its reputation as a windy month, the average wind speed in Ireland in March is significantly less than that in February, and there are fewer gales. The reason is probably related to the average paths of the Atlantic depressions; with the onset of spring they tend to follow a more northerly track, and so have a less devastating effect on our island than their mid-winter cousins.
The air temperature in March rises to an average of 10 or 11 Celsius each day. The highest March temperature ever recorded in Ireland was 24 in Dublin in 1965; the lowest was minus 17 on March 3rd in the memorably cold year of 1947.
Usually there is a marked decrease in the occurrence of both ground and air frost, but this may not be particularly noticeable this year in view of our very balmy February.
Rainfall in March, normally between 50 and 100mm in low-lying areas, marks the transition between January and February, the wettest two months of the year, and the relatively dry period from April to June.