"Degree days" better indicator of growing conditions than average

[quanglewangle]

I take the view that stuff only really grows when the temperature is above 10°C. Of course, different crops have different threshold temperatures, but I think the principle holds.

Average temperature is often calculated as (max + min) / 2 which is pretty crude. For example a max of 15°C may have lasted for only a few minutes and a min of 5°C, which may well have prevailed for 20 odd hours, but would give an average of 10°C. We know that not a lot o growing would take place.

This site https://www.degreedays.net/# will let you download "degree days" - fine grain (depending on your local weather station, maybe hourly).

I choose 10°C as the base temperature and "cooling" (not heating - it's an HVAC site)

Have a look and see how the figures relate to your experience. May take a bit of fiddling to make sense.

[ameno]

Average temperature is often calculated as (max + min) / 2 which is pretty crude. For example a max of 15°C may have lasted for only a few minutes and a min of 5°C, which may well have prevailed for 20 odd hours, but would give an average of 10°C. We know that not a lot o growing would take place.

I hate to burst your bubble, but that's not how average daily temperature is calculated, at least not by any reasonably competent meteorologist or weather report.
It's calculated by adding up all the hourly readings for the day then dividing by 24.
So if it were 15c for an hour, 10 for 3 hours, and 5c for the other 20, the average temperature for that day would be 6c.

[quanglewangle]

I hate to burst your bubble, but that's not how average daily temperature is calculated, at least not by any reasonably competent meteorologist or weather report.
It's calculated by adding up all the hourly readings for the day then dividing by 24.
So if it were 15c for an hour, 10 for 3 hours, and 5c for the other 20, the average temperature for that day would be 6c.

Always happy to be corrected. Thank you.

In my defence, I was relying on UK Met Office

British scientist James Six invented a maximum-minimum thermometer in the late 18th Century that could record the highest and lowest temperature recorded over a period of time. This invention allowed early weather observers to summarise the temperature of the day based on these two extremes, and the average of the maximum and minimum is widely used as an estimate of the mean temperature. This practice continues to this day,

https://www.google.com/amp/s/blog.me...y-go-back/amp/