Is there a way to predict the temperature if you're at sea level, would it be moderate or high?
Unfortunately, there's no way to provide a definitive answer based only on the sea level altitude. At sea level, the climate/temperature will mostly depend on where you are and what time of the year (season) we're in.
At sea level, you can easily be freezing in North Pole, sun bathing in the Caribbean islands or anything in between.
It's easier to predict the temperature if you go higher in altitude. The higher you go, the colder it will get and the less influenced it will be by the location and seasons.
So, if you go at the summit of Mont Everest for example, at 8 848 m / 29 000 ft, you can be assured it will be cold, and you'll never go there to relax on the beach.