This is ridiculous. Seemingly Met Éireann, the Irish meteorological agency, has taken to running with all the other eejits that think that Summer is the three months of June, July, and August. It takes the view that Summer is defined as the three warmest months of the year, based on data over a thirty-year period; so Summer is, as far as they're concerned, June, July, and August in a typical year. It has, rightly, no time for the nonsensical claim that the seasons begin on the Spring Equinox, Summer Solstice, Autumn Equinox, and Winter Solstice, ascribing the use of these astronomical dates as markers for when seasons begin purely to the needs of diary manufacturers and the like, but this doesn't change the fact that their basic thesis is clearly absurd.
Think about it. It was the Summer Solstice just a few days back. What else do we call the Summer Solstice? Yes, it's Midsummer's Day. Midsummer. That's the clue. It falls in the middle of Summer. It's not just a quarter of the way in, much less the day that launches the season. It's pretty much bang in the middle of the season. Go and read Shakespeare, if this doesn't ring any bells.
To have the Solstice fall in the middle of Summer, Summer needs to take up May, June, and July. It's common sense. Likewise with the Winter Solstice -- if it's Midwinter's Day, as it is, then Winter must be November, December, and January.
Despite the meteorological agencies' claims, the traditional European seasons have never been defined by weather. They're not about climate. They're not about fluctuating temperatures, not least because that leads to honest people such as Swedish meteorologists admitting that seasons begin at different times in different years and in different places. They're about light and darkness as experienced in the Northern Hemisphere -- obviously, the months are differnt in the Southern Hemisphere, but the principle's the same. Summer is the quarter of the year when we have the most hours of daylight, and Winter's the quarter when we have the fewest.
For what it's worth, this means that Autumn is defined as August, September, and October, something the Irish calendar makes very clear, as the Irish names for September (Meán Fómhair) and October (Deireadh Fómhair) literally mean "middle of autumn" and "end of autumn".
And yes, I know it often rains a lot in May. So what? Do you remember June, July, and August of 2007 and 2008? Sodden, they were. Absolutely miserable. Dividing the seasons astronomically, so that the quarter of the year with the most daylight is called Summer and the one with the least is called Winter is meaningful, stable, objective, relevant through the hemisphere, and it's how this was traditionally worked out throughout history.