No wonder your palm tree survive
YOUR St Louis MO: 7a (St Catharines On 7a; Niagara Falls On 6b; Windsor/SW On 6b7a)
St Louis IL: 6a6b (Toronto downtown 6b; Toronto not downdown 6a)
Yes, I checked my front yard (facing North) and back yard (facing South with full sun exposures but windy), the backyard is 3C (6F) warmer.