What to do if my ambient side is bit too cool

So my hot side is fine it stays between 96-90, but since weather is getting colder and colder my ambient temp drops. The coldest time dropped down to 76 5am-6am in the morning. Is there anything i can do ?

Two options.

1. Up the ambient outside the enclosure.
2. Add a heat pad and an additional thermostat to the cool side set at the right temp.

Below the Equator?

I had this same problem like a week ago lol! I ended up using this mini ceramic heater with a built-in thermostat. I put it in the area next to my tub to bring up the surrounding temps. You might have to experiment a bit though. With my heater my temps are a stable 80 and 90!
In the future, I'm most likely going to buy another UTH and thermostat to use on the cold side. It's safer and more practical, but an outside heater works too.