V-groove When it is too hot to weld.
I have always found it helpful to carry a heat marker or laser thermometer for welding test plates or vertical groove welds. as a rule of thumb 350-400 degrees is when you should give the steel a little time to cool. I find that it runs best to make starts in the 200-250 degree range all the time, but for fill passes sometimes an extra 50 can help to make a wider pass (more with wire than stick). plus running in these heat ranges comply with almost any code.