Picking black krim whilst still green ?

If you really don't think they will ripen pick them and put them in a shoe box with a ripe banana and they should ripen.

Whereabouts are you?

This may only be a brief spell and the weather may improve. If your plants are in a greenhouse, it has to get quite a lot colder before the plants will be affected.

If you really feel the need, they're no different to any other beefsteak. In the past, I've picked beefsteak off the plant until mid November.

I'm leaving mine a bit longer,it's quite sunny today no panic yet. What you can do is gradually remove the leaves starting from the bottom of the plant just take two side branches off at a time (on a dry day so the cut heals quicker) & eventually uproot the whole plant,remove the soil & worms & hang it upside down somewhere warm in a window or somewhere near a window. So no leaves are on the plant,it's just tomatoes on the vine the roots etc contain some sugars the tomatoes need so other than picking them off the plant when they're green you can take the whole plant indoors if you want. Green tomatoes have thicker skins,being in the sun thins the skins whilst they ripen so anywhere in the sun is best now unless you're picking them then the above advice is best. We had about 3 days of miserable weather & I thought that was it,but the suns out today,this could happen on & off for a few weeks & the soil temp stays warm for a little while after the weather turns cold...