Lots of comments from down below in many different posts. Maybe we can begin to consolidate them on one post, so we can get an idea of what is happening out there in the fields. Here's the latest for tonight:
The area for tonight has expanded a bit, but not any colder. MN is going to get it again, and although it's not that cold, I'm not sure what a multi-night frost is going to do to the crops. Usually, with an early frost like this, it's a one night event, and it's over. Maybe someone else has had some personal experience with this one, and can chime in.
Jen
Farmerguy, your issue isn't until Wednesday:
this is the one pertinent to you. This is the latest for you guys in Manitoba and especially Ontario. 90% plus of Ontartio could take a frost with these, the dark blue is going to freeze. This map hasn't changed much the last few days. It's probably gong to happen.
Jen
Our overnight lows from last night:
Remember, these are National Weather Service readings, usually taken at the towns airport. There is still the 'heat island' affect, and outlying areas can and will be colder than we see above. This map is bad news. Bad, bad news, I don't care how the bears want to spin this and pretend "It's no big deal". It is a big deal. And it's not over.....
Jen
Sure am glad I don't live near Amarillo, Texas. Map shows that they retreated all the way down to 1. 
