My understanding is that frost damages the skin which affects ability to store long term. Whether it will continue to mature at that young stage of development depends on how much warmth and hours of sun light you still have it also depends on the health of your vines. The squash needs all of those to harden up the skin and convert starch to sugar. Here in the Pacific North We(s)t, the vines are done by mid October so there is not much point me leaving the fruits on the ground. I gather them but will put them out in the sun to season - if we get sunny days and its above freezing. This year has been a bumper year for winter squash because of the long, sunny hot summer. I have a number of immature squash - we cook them like we cook summer marrows - stir fry.

Without frost, the squash will continue to ripen as long as the vine itself is still green. IMO low temps actually trigger the squash to ripen faster; that is what I've observed in my garden. A light frost such as you might get there (frost on ground, but temps above freezing) may kill some leaves, but not damage the squash. I usually harvest my squash some time between that first light frost & the predicted freeze, because that gives the squashes another week or two to ripen, and its easier to find the squash after most of the leaves have shriveled.

Good thread! We are not use to having cold weather until maybe January, but this year 31 degrees is posted for tonight. I thought I had until Christmas for mine all to get ripe, but now I don’t know what I’ll have whenever I eventually get back home. It’s good to know what can be done in any case.

if freezing or just below, throwing a thick towel or blanket over each squash should save them. I'd only do that though if warmer temps were expected the next day - and if there was no wind. Below 32 degrees with wind is a hard freeze, best to bring the squash in if that is in the forecast.

The finale to the Kabocha season!