How much do you have left now after charging overnight? I was able to make it down with 60 miles left on the gauge in about 40 degree weather. You gain about 15 to 20 miles coming downhill and today is sunny. Just make sure you pick a route that could come down and no road closure. You won't have enough to go back up the hill and down another path.
Next time you should charge up at Fontana or San Bernardino before going up. And you probably forgot to turn off Smart Summon standby to lose that much overnight.