Im running out of intermediate sized pots and would like to put my tomatoes out in the balcony in their growbags now that we have some sunshine in the forecast.

But my night lows are still in the 40s (5-8C). No frost but still cold.

Should I suck it up and still bring them indoors, or the seedlings should be fine outdoors, just maybe grow a bit slow until it warms up?

Tomatoes are pretty cold hearty. 40s certainly won't hurt them, but doesn't help either. They'd probably like it inside at night when it's cold. Just depends how much labor you want to invest.

I believe the soil staying relatively warm during any cold snaps makes a positive difference. My tomatoes this year have been through a few nights in the lower 40s and possibly a bit colder (high to mid 30s), but the soil temperature never dropped below 60°. The tomatoes had no lasting effects from the cold nights, that I can discern, other than some lower leaf damage on a few plants that got pruned away and did not spread to upper leaves.

Nights in the 40s certainly don’t help tomatoes, but nights in the 40s are not an automatic deal messer upper or deal killer either. Maybe there’s the duration of the cold that comes into play and how warm are the daytime temperatures.

Where I am, if I waited until I was certain the temperatures would never dip below 50°, I’d have to wait at least a month longer or more to transplant my tomatoes into the beds. What I would lose with a plan like that is a good chunk of the heart of the best tomato fruit setting weather we get.

Risk vs. reward, in my experience, the actual and lasting risk of harm to the tomatoes from a few nights in the 40s, given the 60 plus degree soil temperatures, is far less than the risk of planting my tomatoes too late to take full advantage of the prime fruit setting weather.

Basically, I lose much more fruit by waiting to transplant until I’m certain a night below 50° will not happen than having my tomatoes in earlier and incurring a few sub 50° nights.

But, that’s the math for zone 9 Texas coast. The math might be totally different in other places, give all the variables in climate.

I think my problem is if I wait until we are in the 50s i wont be planting until june.

Sigh...i just dont have a tomato climate. It is what it is and just need to work with what I have.

I usually wait until I have three days in a row with lows close to 50F/10C and highs above 60F for the transplant. The important thing is not to give them transplant stress and cold stress at the same time. After settling in for three days, they can take some colder nights.
OTOH many times if my plants are getting too big indoors but the weather isn't perfect for transplant, I will put them out there in their beer cups and they are just fine hardening off like that until I get my transplant window.
If nights are still that cold, I would put them out in the intermediate pots they're in for a few days to get accustomed. If the grow bags are more or less ready, you can stand them on top of the bigger volume of dirt, to moderate the night temperature. I'm assuming the sunny days are over 60 F as well.