This photo was taken on St. Patrick’s Day, the day this year which, at my latitude, happens to also be the equinox, or day when we have equal day and night lengths.
The actual equinox is 2 days later (St. Joseph’s Day this year, and about as early as it can fall).
Nevertheless, in my state, it’s snowing, it’s predicted to snow again on the equinox and it can snow well into May.
This is what my old-fashioned hydrangea macrophylla ‘Nikko Blue’ looks like right now. It’s been very warm, despite the late season snow nuisance. In fact, by the weekend, it will rocket up to 70 degrees, before falling back to something more seasonable.
But the warmth, and then the snow on top of the emerging buds, kills the flowers off of these old-fashioned hydrangeas every year.
Newer varieties, or varieties that bloom on new wood, are not killed by late freezes. Luckily I grow both kinds in my yard.
Gardendaze 
Gads! My hydrangeas can be skimpy on bloom because I get impatient and prune them down like roses, but that is a different issue. You know, there are so many weird cultivars of hydrangeas nowadays. Because I dislike new cultivars, I don’t notice them much. However, there are some that can be pruned down like roses and still bloom. I am actually impressed by how some of mine bloom. (I do not know what they are, but I doubt they are new cultivars.) Anyway, such cultivars might be more likely to recover from damaging weather to bloom a bit later. I mean if mine can bloom after getting most of their blooming stems off, there must be some that will bloom after getting snowed on.
Oh yes, there are lots that will bloom after getting snowed on and I have those. What we all stupidly try to grow here in Connecticut are those gorgeous blue hydrangeas that they have on Nantucket or Cape Cod. But of course inland Connecticut isn’t anything like that maritime climate–so we whine.
BTW, more snow today. Gotta love spring here. We’re getting more snow now than we’ve had all winter.
Karla