I have 3 water sprinkler systems at the front and back of my house. I used to turn them on and off daily one after another as there is not enough pressure to run them all at the same time. So now every 5 hours a script runs on my home server, goes out to the Internet, checks the humidity in my town and checks if the current humidity is below 80%. If it is, then first WeMo switch will turn on first sprinklers system, and the same goes with the second and the third one after another and 3 times a day. How it works? The script checks the weather, and sends an email to the IFTTT platform using #current_humidity and once received, IFTTT turns my WeMo switch ON. To turn them off im using the in app built feature so after 5 minutes turns the WeMo off no matter what. This way, if the internet goes down, WeMo will still turn off and not flooding the front and/or back yard. Really fun project.
I've actually changed the way WeMo gets triggered, I no longer use IFTTT to turn WeMo ON, I only use IFTTT to log the times when WeMo came ON into a Dropbox text file. To turn my WeMo ON now, I use the same script that checks the humidity, which now (instead of sending IFTTT an email to then trigger the WeMo action which I've noticed sometimes happens with a delay of up to 1.5 hours! ) now sends an INSTANT command to the "WeMo server" to turn ON my desired WeMo unit. So now to recap, 2 times a day, say 7am and 4pm, the script will run automatically and go out to the internet and brings me back the humidity value, checks against 80% and if lower, it sends a command to WeMo server to turn ON the desired WeMo switch which then turns on the sprinklers system. The WeMo built in Turn Off function will turn the sprinklers off after 5 minutes. It works like a charm, no delay at all, the sprinklers come ON a second after the script runs ( unless the humidity is over 80% ) when I get an email instead reporting the humidity value and that the script ran but because of the weather conditions it didn't trigger the WeMo script/switch/sprinklers. I'm not looking for other units to have to maintain and watch battery levels... My setup works the way I wanted it to work.
Another update on my setup. I now use HASS (Home Assistant) to control my WeMos. This way I have the opportunity to check the current weather condition and predicted weather and take a much better decision on when the sprinklers should come on. I now have 4 sprinkler systems and work a treat. Checked on them when was raining and before and after the rain and because of the prediction the sprinklers didn't get triggered as expected. I'll add some code soon if interested in my blog vio.net.au thanks