But there's one thing I've noticed...they can handle low temps but here, in winter, it doesn't get much warmer during the day. They all seem to tolerate low temps but need higher values (>59 F / 15º C) during the day.
In January and February it's frequent to have a max of 50 F (10º C) during complete weeks.

Mexican Laelias can have temperatures like that in the winter. If you can find them, try some.

And I think Cattleya (Laelia) pupurata is also worth a try, based on what I've been told.

I know it isn't a Cattleya, but it sounds like you're environment would be great for growing some Masdevallia out there.

From what I've seen, Laelia bahiensis is the most suitable for me. A south balcony, protected from the north cold winter winds and plenty of direct sun.
And this one I can get for 19 €...

Well, I think I can't, although I'd love to. Summers here are hot and dry, even indoors.

My northern California climate is similar to yours except I get more cloudy foggy days.
I grow Laelia hybrids, C. amethystoglossa, Encyclia tampensis, Barkeria spectabilis an several C. Noids in a greenhouse that is kept above freezing. The temps are usually around 60 - 70 on a sunny winter day.
Do you have a way to cover your growing area with something that will let the sunlight through and heat it up during the day?
I have my Cymbidiums on a southfacing protected porch.

Maureen

My idea is to put the plant, at least during the cold days, in a southern balcony. The only protection is against the northern winds. So it has to be one that can stand lower temps of 40 F and max around low 50's (winter temps) as well as direct sun.

Mine are on a northfacing balcony, no protections. They do fine.

You might try hybrids of Encyclia (Epidendrum) tampensis like this one:
Epicattleya El Hatillo 'Nina' at Santa Barbara Orchid Estate

The best plant for that condition is Laelia anceps... they can tolerate wide ranges of temperatures and good sun... they even survive a quick snow! There are so many colour varieties as well... and grow quickly to make magnificent displays!


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Anceps, autumnalis and bahiensis are the best options. I can get a bahiensis but their flowers are smaller. I think I'll wait and try to find some of the other.
I'm planning a visit to an international orchid show in Lisboa. Probably there I can find some specimens.

In the meawhile, here's a link with useful information about Laelias.

This one is a "jewel", a document with detailed info about each of the mexican Laelias... to those who are interested.

Laelias of Mexico - Herbario AMO