I had assumed that most of Canada would be later than the Northern tier of the US, but apparently I'm wrong. I wonder if it's because the summer days get longer the farther north you go, and at some point you actually get earlier ripening? Or maybe it's all local weather. In any case, thanks for the correction.
It is, but you don't find much winter wheat outside of Southern Ontario, which is actually pretty far south in the grand scheme of things. The most southern end of the province is on the same plane as California.
The Canadian prairies, where most of the wheat is grown, are all about the spring wheat. That's typically a September harvest.
> Idaho, Minnesota, Montana, Oregon, Washington, and Wyoming
Only one of those states is not contiguous with Canada. Given much of the same environment, they share a lot of the same farming practices as western Canada. In other words, your dates no doubt include spring wheat, despite what the opening section of the document says. This explains the wide variances (July - September) in some cases, with winter wheat being the early crop and spring wheat being later.
Who is harvesting winter wheat in the fall? Even here in snowy Canada it's a late harvest if the winter wheat comes off in August. Mid-July is typical. Spring wheat is a different story.