Yes, some of those varieties are more cold tolerant. Stupice will set in cooler temperatures. Soil temperature is the important factor. We circulate warm water through the soil to heat things up. We also us Walls of Water which release heat during the night. In the field, we use caps made of a reflective bubble wrap.That's what you see in the photo.
In order to breed true freeze resistance into tomatoes, a project several us are working on, wild species are crossed to very hardy strains of tomatoes.
Lee

Tomatoes can take temps in the low forties and mine have taken in the thirties even. I started my large ones sometime in Nov covered them in my cold frame and had temps in the low 20's in Dec in my greenhouse.Just make sure if you get a frost to cover them overnight,I use frost blankets but anything over the tops and all the way covered to keep them from freezing should be fine.Good luck with yours.

Just a side note-soil in raised beds or pots is not necessarily warmer. The soil is exposed to the elements on all sides rather than being insulated by the surrounding soil and is therefore more susceptible to changing temperatures.

I have been growing tomatoes all Winter under cover of my patio. Some will set at low temps, others will not. Small reds are often a good bet. Siberian is said to set fruit in the high thirties. I am growing some now. I have a Bolseno Hybrid which has continued to set and my lows have been mid to high 30s. Sun Gold has also set well. Google cool climate tomatoes for ideas.

Thanks everyone. I guess I should have clarified that I had read some posts that suggest that temperatures in the 40s can permanently stunt very young plants, which I obviously want to avoid. I've had an established (summer-planted) tomato that survived the frosts we had in Dec, but I don't know how young transplants deal with cool/cold temps. I think I'll be planting a Stupice this weekend. Thanks!

Early, cold (rather cool) tolerance.
Check out these:

Glacier, Siletz, Legend, Stupice, Oregon Spring, Siberia, ...

I am going to grow 3 of those named above this season, as we have very COOL spring and late summer/early fall weather.

Hope it helps.

It's not unheard of to get frosts right into the first week of June here in Saskatchewan. If I've put the tomatoes in the ground in late May and a subsequent frost is in the forecast, we cover them with blankets for the night, exactly like we would in the fall. The plants always reach the same size as they do every year. We don't notice any stunting or drop in production with any of the early determinates. The mid and late indeterminates take lower temperatures much harder.