Could it be Blue River II? Here is a link that might be useful: Blue River II

Several years ago my aunt gave me perennial hibiscus seeds from her Toronto garden. They germinated and grew easily, and I planted them about a foot or so from the south facing foundation. They bloomed very late August and survived several light frosts (no doubt being so near the house helped). They survived winter with no special protection and began growing in May the following year. Again, being near the foundation, snow melted and soil warmed earlier than anywhere else in the yard. Again they didn't bloom until late August. They turned out to be bigger plants than I had planned for - around 3', but were sturdy and healthy. I had to remove them when I reconfigured the area and didn't have another suitable place for them so they got tossed. I had more seed, so I figured I'd start more when the time was right. Last year I gave the rest of that seed to my sister who lives outside Calgary. They were still viable, germinated and she also planted them very near the house. It's the first winter though, so don't know yet of their survival. Lack of snow cover there can be an issue. I think they were Hibiscus moscheutos. Here are the plants in mid-July, to the left of the blooming Adelaide Hoodless And here's the bloom

Gorgious!!

This is a Hibiscus coccineus hybrid. Plant's foliage suggests it could be Lord Baltimore, but flower seems a bit small for that cultivar. Perhaps you can post more pix of it in bloom. It is a real winner!