Hello all 
What would be the best way to trigger once when the sun is at it highest? I want to enable my irrigation system when it’s especially hot, with high uv.
Sun elevation > 45 degrees?
Best regards
Isn’t a not so great idea to start the irrigation when it’s the hottest as most of the water will evaporate or even harm your green or flowers by boiling it to the fullest?
AFAIR you should water in the morning and in the evening.
Maybe you should first have a look at gardening advice pages and then try to automate it.
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If you want to burn your plants and lose more water to evaporation you could use a trend sensor to determine when the sun stops rising.
Use solar_noon
That’s funny.
Trend Sensor is a better idea as @Tinkerer said as its not a 3rd party integration. I learned something new too. Never used that sensor type.
I thought that the time that the sun is at it’s highest point in the sky (no matter the season is when the solar azimuth is 180 degrees (in the northern hemisphere - 0 degrees in the southern hemisphere).
am I incorrect?
if I’m correct then you can just use that info in your automation.
{{ state_attr('sun.sun', 'azimuth') = 180 }}
The sun is at its highest at solar midday, the next midday is an attribute of sun.sun.
But as others have said, that is not the best time to water.
It’s already watering at sunset and sunrise when no rain is expected in the next few days.
All my plants are mulched and my irrigation system sprays under the mulch. I don’t think this would attribute to higher evaporation.
The only thing I want is to use an extra trigger when we get heatwave 30+ degrees celcius to water my plants a little bit more…
Maybe add a soil sensor to monitor how dry it’s actually getting? Then irrigate based on that
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Well that is easy enough to do. Read the automation docs. A numeric state trigger.