Congrats! Are you able to determine which species your bird is? The temperature at present should not give any hummer any problems. Most North American species can tolerate temperatures down to the upper teens for overnight, if the temperature rises above freezing during the day. Just be sure to keep the feeder going as long as the bird is present.
I would recommend feeding a solution of 1 part sugar to 3 parts water to give the bird more calories for her efforts. Quite a few natural nectar sources have nectar sweeter than that. At any rate, enjoy while your special visitor is with you!
Nancy L Newfield
Metairie, Louisiana USA
USDA Zone 9