'frost days' is correct and usable in written English.
You can use it to refer to days that are so cold that they cause frost. For example, "We had several frost days in December this year."
The assessment of impact and risk potentially caused by climate change has been evaluated for following 7 outdoor environmental variables under the two IPCC emission scenarios A1B and RCP4.5: Freeze Thaw cycles Salt crystallization cycles Sea level rise Frost days index Dry days index Wet days index Heavy precipitation Index Tropical day index.
Similarly, the evaporative demand, expressed as mean day-time vapor pressure deficit (VPD) each month and the number of frost days (< −2°C) were calculated from monthly mean temperature extremes using the 3-PG function tools (3PGpjs version 2.7, 3-PG version 1, September 2010).
They found that despite the fact that northern populations faced up to 70% more frost days than southern ones, they were more resilient.
The new normals provide monthly, seasonal and annual averages for many aspects of our weather, including maximum and minimum temperatures, number of frost days, sunshine hours and rainfall.
A United States government report published in 2008 noted that "in recent decades, most of North America has been experiencing more unusually hot days and nights, fewer unusually cold days and nights, and fewer frost days.
Additional derived variables included degree day indices, frost free days, precipitation as snow, 30-year minimum and maximum temperature extremes, and evaporative demand indices.
These studies have revealed latitudinal and elevational clines for height growth, or bud phenology (particularly timing of primary growth cessation or bud set, but also timing of bud flush in some species), and cold hardiness that correlate most strongly with temperature gradients of population origin (e.g., mean annual temperature, mean coldest month temperature, number of frost free days).
The study, demonstrated that the number of frost-free days, and a delay in the first autumn frost, has occurred since 1995 as a function of latitude, extending the ragweed pollen season into the fall, particularly for the more northern locations.
The other mode of measurement for growing seasons is stated in terms of frost-free days, i.e. the average number of days between the last frost of spring and the first killing frost of fall or winter.
At Dalian there are about 200 frost-free days, while at Shenyang there are between 160 and 180 frost-free days per year.
