I'm not sure the final low, I leave for work at 3am and my thermometer is back by my garden shed, so I don't walk right by it as I leave in the morning and I drive an older vehicle with no thermometer built in lol. I need to invest in a digital station for more accuracy. I have noticed I have gotten frosts before where the higher and lower elevations around me did not. I'm set-up basically like you described as a bowl, but a 3 sided bowl. West, east and north are higher up and due south is lower elevation. The trees are also cleared out around the house so that may help some.