I’m currently experimenting with measuring grass minimum temperature. The grass minimum is defined as the temperature recorded in open air ground on short turf, with the bulb of the thermometer just in contact with the tips of the blades of grass. It is also described as the temperature at 5cm or 2 inches above the ground. The difference between the air temperature typically measured around 4 to 5 feet above ground and the grass minimum can be substantial on clear nights with little wind and strong radiational cooling. When I have enough data to plot, I’ll post the graphs. I’m using a Davis wireless temperature station for the grass minimum temperature. Since it is directly exposed to the sun, the daytime readings have little use and could be cause for concern if I posted, frequently reporting over 100º this summer! The grass minimum is the lowest temperature recorded between sunrise and 0900.
I have opted to just post the recorded minimum from the sensor on the garden weather page of my website available here.