Getting actual weather statistics

Has anyone come up with a way to get actual weather statistics for today (or yesterday)?
I’ve come up with some algorithms for my garden watering system so that I can automatically adjust the watering time based on rainfall and high temperatures using DarkSky.

I am not sure though exactly what the monitored conditions are reporting. The DarkSky API documentation is not clear either and in fact this has been raised on the DarkSky website forum too.

I just wondered if anyone had already invented this wheel? If not I guess I’m going to have to try and watch what the component tells me, look out the window and try to work out the connection.

I’m in the UK and ideally I’d like to know the high temperature for today, yesterday or whatever, along with the amount in mm of rain that fell. As far as I can tell DarkSky is the most likely candidate to get this information.

I’m creating my own precipitation history and trigger the drip system every other day, but only if I the value is below 100U:

I use a bunch of scripts to save the actual precipitation of the day every night just before midnight after I moved the older values one day further out:

Every day at 5:55AM I check, if the overall value (including the precipitation so far that day + the forecast for the day) is still below 100U; you can see that weight every value gets in the picture.
If the value is above 100U I do NOT turn on the drip system but check the day after at 5:55AM again.
If I did it again I would probably store the values in various ‘input_value’ fields rather than in json files - just a I’m already doing for the ‘Last Run’ and ‘Next Run’ info.
I like your idea of dynamically adjusting the time the sprinkler runs, but - as you can see from all the 0 values - it might be an overkill in my situation: raining season is over already :disappointed:

Thanks for that @chairstacker, what I’m doing is not too dissimilar. I also keep my own history (in input_numbers :slight_smile: ) and weight each day as you do. I like your idea of regularly looking at the forecast for today and including that.

What weather sensor do you use and which monitored condition have you decided gives you actual precipitation for the previous 24hrs when you check just before midnight?

EDIT: And perhaps more interestingly how do you calculate how much rain has fallen already today? I’m currently using dark_sky_precip_intensity * 24 but I think that that is only a current forecast for the whole day (or is it for what is left of the day?).

I agree, some of what I am doing is way over the top but once I’d started… :roll_eyes:

Living in the UK of course our summer can be a week of blazing sunshine followed by a week of torrential rain, repeated with random durations until winter when it just rains a lot :slight_smile:

I guess that’s the slight difference in precipitation patterns between California, especially where I live, and the UK :wink:

I have my own little weather station ( and record actual precipitation by having it uploaded to the Ambient website as well as Wunderground.

That’s where I then get the data from, i.e. precipitation today - which I save just before midnight (for keeping the history) and use as well at 5:55AM.
Wunderground also provides a forecast (pws_precip_1d_mm) that I add into the equation, but with only half the weight of actual data.