It will require more energy to get yourself up to boiling, for sure. Are you using a cooler to keep your mash at temp, or constant flame? With a cooler you should be fine, if it is a good quality cooler that is.
Technically/theoretically speaking from someone who took some thermo and heat transfer classes is that you should still be able to keep a constant temp once you hone in on your flame size. I would still suggest you stay out there and watch it. If using a cooler though just leave it be, measure the temp when you are done and see how much heat you lost.
As far as sparging, if batch sparging it should be fine. Fly sparging again will require a lot of watching.
Long story short you should be fine, it just will take some more attention. Go ahead and brew.
All from someone from Cali coast where I get 45 at the very coldest ever in the morning.