Not surprising. Jaguar's are easily one of the hardiest species of cichlids like convict's, Jack Dempsey's, Mayan's, and ect.
My mother was from Romania and she told me that the summers their get REALLY hot, and winter's 'usually' aren't bad.
My brother told me he and his friends did science experiment with convict's. They bought a 10g tank with 4 small convict's. The convicts were left outside all spring, summer, fall, and winter without a heater only a filter. Surprisingly only one died in the summer because of the heat, and the rest survived the YEAR! My brother lives in Colorado too, Colorado get's some nasty ferocious winters. He explained that they stay at the bottom huddled together. I was shocked to hear that.