Does anyone know a program that takes weather station data (eg weather underground) and calculates chill hours?
I know there are ways people can export to excel… too much work. Just curious if there is anything more automated.
I am aware of this one but the weather stations are more limited:
Hi @JamesN,
Rhetorical question. Is chill hours exact? Who can guarantee a tree flowers in 610 chill hours but not 570 chill hours? What about the effect of exaggerated sun/shade during winter due to local features or latitude? I.e., N facing vs S facing makes a big difference for the wakeup time of the plant and I would make a logical guess that it could affect fruit bud creation as well. Also most of the chill hour figures are given in the 100s of hours, which suggest it probably not too exact on purpose.
If you accept chill hours may not be exact, but rather an average, you may be better served to know the average number of chill hours for your location.
@JamesN
I calculate mine by adding up the number of whole hours below 45°F between October 1 and April 1 – or when each tree breaks dormancy (whichever comes first). If the data is hourly, then don’t include single hours occurring in a single day.
Note that elsewhere in the U.S. they are concerned with a low temperature limit but it just doesn’t get that cold in your or my location.
@sockworth
Out here James and I are concerned with whether we received 200 or 500 in a particular year. Maps aren’t particularly useful to us, because 15 miles away in most directions is a different climate zone.
I see, I believe all data is there and someone from wunderground could code up in a day the chill hour data to provide to all fruit growers.
@sockworth
I wish it was that simple. After studying the trees and the data for 30 years I’ve concluded it is not.
Please understand that several of us out west have our own weather stations for the above reason. Let’s not trample on James’ request any further.
Hi @Richard , I’m not trying to trample on anyone’s request. I’m just saying the data is there It could be calculated algorithmically. If the data is there, I could write an excel equation to derive the chill hours.
@JamesN if you have the data in a google docs excel sheet, I can calculate it for you.
Chill hours maps of the US or parts of it are available online. Just Google “us chill hours map”, and you will find a number of choices. I haven’t tried any of these but have used some of the degree-day maps, which are similar and can be quite detailed.
I see one called chill hours, but there are limitations. It allowed me to get a station near me, but then I get
How much is a “chill hours” calculation worth to you? PM me with any offers.
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As Hounds, and Greyhounds, Mungrels, Spaniels, Curres,
Showghes, Water-Rugs, and Demy-Wolues are clipt
All by the Name of Dogges: the valued file
Distinguishes the swift, the slow, the subtle,
The House-keeper, the Hunter, euery one
According to the gift, which bounteous Nature
Hath in him clos’d: whereby he does receiue
Particular addition, from the Bill,
That writes them all alike: and so of men.
It ain’t particularly simple because there are several different algorithms in the catalog coming under the heading of “chill hours.” You might as well really program them all to have them all ready at need.
I have credentials for this task. See, “Phenology,” an extension to the ever popular WeeWX Linux app.
I had found a site years ago that took data from any Wunderground station but it is no longer functioning.
The maps you find online vary quite a bit. Louisiana Ag has a map but it’s very old.
I’ve calculated based on my own weather station and have not found the results to be of much use as I can use two different methods and go from hundreds of hours in the negative to over 500.
I’ve just decided to try choosing trees that are 500 or lower. Time is the only thing that will tell me if that particular variety will fruit for me, and I know that it might not be the same the following year.
Thanks.
Looks like it only calculates the current year for chill. Since we are past October 1st it’s started for this winter. I was hoping to compare to my calcs for last year.
I’ve looked numerous times over the years for a website.
Good find.
Sticking with the simple >32° and <45° calc, as of this AM I am at 196 hours.
That’s not a bad start for down here with 3 more days of cold weather to add for December.
I will stop the clock at bud swell for any given tree…
Of course the trees don’t care about my calculations, so we’ll see over the coming years if it’s even worth trying to track and reconcile with flowering and fruiting behavior.
I will build one this week.
Many chill hour models are common and when tested, they produced very different results, as much as 2X depending on the model. Very interesting information but probably not very useful in predicting bloom time.
If you are located in NC you can use the chill hour model from NC State which includes 9 different models including the Mainland Model for Blueberries. Mainland model shows 1808 chill hours for Blueberries but the Richardson model only shows 891 hours for Peaches.
Edit: I should have mentioned that the website shows how the calculations for each of the chill hoour models are made which is useful even if the program only allows chill hour calculations for NC
I know the Peach model is not even close to right since my Contender Peaches at 1050 chill hours have already set fruit.
