Either way, it's one of those things that some people go for, and others don't. And whatever. Personally, while I might make some offerings, I'm more likely to be concentrating on Là na Caillich given my focus. But it doesn't hurt to do a bit of reading, and it so happens that I did and what I found has prompted a bit of think about it all.
One thing I've always wondered about is the fact that Là na Caillich - as far as I'm aware - isn't a thing in Ireland (or Man). But even in Scotland, Là na Caillich and St Patrick's Day are often seen as interchangeable, especially when you look at the kind of weather-lore that abounds for this time of year. So that's interesting in itself, because it suggests some sort of link between the two, and their associations with the season. The reading I've been doing has reinforced that.
While Scotland has Là na Caillich as it's "official" heralding of spring, Ireland has a few springtime associations that fall on or around St. Patrick's Day. In Ireland, there are a number of customs associated with St. Patrick's Day that could be seen as having spring-time connotations, including the fact that he is associated with the gales that often coincide with this time of year. The whole greenery thing could also be interpreted as being associated with the spring ('cos...things are turning green again, life is stirring...you know the drill). There is the tradition of drowning the shamrock, too, in a beer that's been specially brewed for the day. This beer is begun in February, and it's tempting to see a coincidence between that timeframe and the fact that Brigid ushers in the first stirrings of spring at her festival, and then ultimately triumphs over the Cailleach who admits defeat at Là na Caillich. I'm just speculating, of course, but the coincidences don't stop there.
While the reason for drowning the shamrock isn't clearly stated, it's repeated the following day (with fresh shamrock). This day is known as Sheelah's Day, and things start getting really interesting:
The day after St. Patrick's Day is "Sheelah's Day," or the festival in honour of Sheelah. Its observers are not so anxious to determine who "Sheelah" was as they are earnest in her celebration. Some say she was "Patrick's wife," others that she was "Patrick's mother," while all agree that her immortal memory is to be maintained by potations of whisky. The shamrock worn on St. Patrick's Day should be worn also on Sheelah's Day, and on the latter night be drowned in the last glass. Yet it frequently happens that the shamrock is flooded in the last glass of St. Patrick's Day, and another last glass or two, or more, on the same night deluges the over-soddened trefoil. This is not "quite correct," but it is endeavoured to be remedied the next morning by the display of a fresh shamrock, which is steeped at night in honour of "Sheelah" with equal devotedness. — Every Day Book, vol. ii. p. 387.While Sheelah is dismissed as Patrick's wife or mother here, the name immediately brings to mind Sheelah na Gig, though the similarity of the name alone is hardly much to rely on. We need to look at the broader picture: Like the Cailleach, who is associated with the final blasts of wintery storms around this time of year, and whose day on March 25th signifies the end of them, Sheelah (Síla, Sheelagh or Sheila) is associated with the storms too (or else Patrick is). Here's something from Newfoundland, for example:
About St. Patrick's Day [the sealers] start, most of them waiting until after Sheilah's brush or the equinoxial gale has passed…
Similarly, the term "Sheila's brush" (or "blush") refers to the "...fierce storm and heavy snowfall about the eighteenth of March," and she is described as walking the shore in a long white gown (i.e. of snow). In Ireland, it's said that if it snows on or around St. Patrick's Day, "Sheila is using her brush" (snow as dandruff!), and a German traveller touring around Ireland was told that Sheela-na-gi meant 'Sheela with (or of) the branch. Gi or gig in this instance may relate to géag, branch, so it seems there's a clear link between Sheelah and the idols found on so many churches and castles across Ireland. Interestingly, one of the alternative meanings of géag is an "image of girl (made for festival)."
Thinking back to the Cailleach, what does she do but roam the land with her wand (or mallet), hoping to maintain her wintry grip by using it to blast the vegetation? She is also associated with causing snow, with sayings such as "the Cailleach is going to tramp her blankets tonight" giving the most obvious evidence. Otherwise, she is milking her goats, or she has washed her shawl and left it to dry on the mountains, covering them in snow as she shakes it out.
All in all both the Cailleach and Sheelah have associations with the storms and harsh wintry weather that happen around this time, and which are seen as winter's last gasp. They both have days dedicated to them around this time, which happens to coincide with the equinox. And it so happens that the tomb of Loughcrew, on the hills of Sliabh na Caillich, have an equinoctial alignment too (just throwing that in there).
The similarities here are highly suggestive and extremely interesting. That's not to say that I think Patrick's Day is really pagan or anything like that, but there's a lot to ponder on. In particular, it all does bring up a lot of similarities between the Cailleach and Síla that I've always wondered about (see also).
Anyway. Whatever you're up to - or not - tomorrow (or they day after...), have a good one.