Pennsylvania Randonneurs 300k was yesterday.
Spring had been just around the corner for a month. Just last weekend we were out riding in sub-freezing temperatures. Thursday morning was chilly as usual. By Thursday afternoon Spring was actually here.
I did my first 300k of the year yesterday too, but up in MA (this was the Westfield Spring 300k) it wasn't fully spring. Or, at least, it was only fully spring for the fast pack who finished before nightfall; a cold front rolled in just as dusk also dropped the temperature, and so temperatures ranged from a high of 81 to a low of 36 degrees (according to my garmin, but the high point was riding, not sitting in the sun by a control, so I think it's reasonably accurate). At least the predicted rain coming in with that front held off; I carried a rain jacket the entire day that I didn't use, but was still glad I did.
Pretty sure that's the largest temperature swing I've ever experienced on a bike; hard to pack for without overpacking, but except for confirming that my "winter" shoes aren't enough even in dry mid-thirties weather if it's that cold for long enough, I had everything I needed.