I had heard it suggested one time that the seasons in the temperate
zone should be six rather than four in number: summer, autumn, locking, winter, unlocking, and spring. And I remembered that as I straightened up beside our manhole, and stared and listened and sniffed.

There were no smells. There was no movement. Every step I took made a gravelly squeak in blue-white frost. And every squeak was echoed loudly. The season of locking was over. The earth was locked up tight.

It was winter, now and forever.

(The scene, of course, is the total devastation of the world by the accidental release of a quantity of "Ice-9" with a template of a new crystalline structure which instantly locks up all the free water in the world.)

Over the years, I've tried to find out who Vonnegut's protagonist was referring to, but have been unable to do so. My most recent search (just a few minutes ago) pulled this from a sermon by a Unitarian minister, Victoria Stafford:

Kurt Vonnegut writes wisely about this time of year:
One sort of optional thing you might do is realize that there are six seasons instead of four. The poetry of four seasons is all wrong for this part of the planet, and this explain why we are so depressed so much of the time. I mean, spring doesn't feel like spring a lot of the time, and November is all wrong for autumn, and so on. Here is the truth about the seasons: Spring is May and June. What could be springier than May and June? Summer is July and August. Really hot, right? Autumn is September and October. Seethe pumpkins? Smell those burning leaves? Next comes the season called Locking. That is when nature shuts everything down. November and December aren't winter. They're Locking. Next comes winter, January and February. Boy! Are they ever cold! What comes next? Not spring. "Unlocking" comes next. What else could cruel March and only slightly less cruel April be? March and April are not spring. They are Unlocking.

So it seems that perhaps Vonnegut's narrator was referring to Vonnegut himself. Unfortunately, Reverend Stafford didn't provide any reference to what she was quoting from, and additional searches on the language Vonnegut used brought up nothing.

I've got most, if not of all, of Vonnegut's published works in my collection, but I've never been able to pin this down -- any help would be appreciated.