Hi Wanda - you might have a hard time getting pant to dry at temperatures that low. I would read the can of paint and if the weather is below the range, don't paint.
Here's a link with some tips for you, Wanda:
My honest opinion? Wait. That door needs to be kept open for several hours at least. Do you want to lose all the heat in your home? Think not.
Does it have to be done now?
If the door swings in you can seal the opening with a tarp to reduce heat loss. You can then paint the door in the comfort of your entryway....but....you still can't paint the outside door trim so the job is only half done.
If you choose this method, use a zero voc paint so you aren't breathing fumes. Also keep in mind that it will take several hours to dry so use a heavy tarp on the door opening.
I agree with Kc, but it would be easier if you took the door down to paint it. Always let it warm up before you paint if the temp is that low or it would be the same as if you were painting it outdoors.