Pull the spear (newest frond in the center thats just coming up). If it pulls then its dead (well sort of). If it doesnt pull, then there is a chance it is alive.
If the spear pulls then it might not be dead. As long as it has some green fronds, it might grow a new spear when the warmer weather is more permanent. If it declines, then you can always cut the top part of the palm off (only down far enough to get to healthy bud tissue) and hope for the best. If you cut below the growing point, it will not grow back.
I hope it survives!
-Alex