Those who work as meteorologists base their concept of the changing seasons on the average temperature at these latitudes.
They designate the coldest three months as winter and the warmest three as summer, so almost by default the three autumn months turn out to be September, October and November. By this reckoning autumn 2001 began last Saturday.
September provides a gentle introduction to this new season. As we return to school and work we recall despondently, despite the mediocrity of recent months, that "summer's lease hath all too short a date". It becomes increasingly obvious that the year is on the turn, its middle age is come and it starts the slow and sad decline into winter.
Although this month's equinoctial sun is of equivalent strength to that of March, the early autumn is made softer and more mellow by the lingering warmth of recent summer, and by the still-luxuriant foliage on the trees.
It is a month that, by and large, avoids the limelight; early autumn shuns the headlines of the record books, and lacks the brash exuberance of spring.
But September can be ambivalent and indecisive. Sometimes it is a windy, blustery month, characterised by a regular procession of depressions moving eastwards across the Atlantic, and passing close to Donegal and Mayo.
Occasionally one of these may harbour the atmospheric remnants of some almost forgotten transatlantic hurricane, as, for example, did the storm we recall as Hurricane Debbie in September 1961. Many of the records for extreme wind speeds established on that day still stand.
But more often the march of the Atlantic lows is halted for a time by a strategic anticyclone, and one or more spells of fine, dry, quiet weather come along. This, combined with the lengthening nights, makes it an ideal month for the dews and mists that we associate with early autumn.
The quiet air, cooled by the ground at night, slides down into the valleys and leads to "ponding" of the cold air in undulating countryside, a phenomenon often detectable on a fine September evening.
September is a month of slow transition, with summer yielding ground to the approaching winter. It often has a gentleness that has all the hallmarks of mature tranquility, or as Longfellow noted, it is a time when
With a sober gladness the old year takes up
His bright inheritance of golden fruits,
And pomp and pageant fill the splendid scene.