Observatory Temp Control and Precooling

I am just looking for thoughts. It’s kind of a summer question being asked in the middle of our northern hemisphere winter.

I would love to hear ideas about the logic and the algorithm for a Dragscript to accomplish my goal in this scenario
The observatory is completely automated for unattended use. The observatory is a 16.5 foot Ash-Dome located in a facility/home that is fully automated (Vantage brand), a MyHome compatible, system. The observatory itself has a dedicated AC system, a small heat pump split unit that is sufficient (actually oversized) for the cubic feet of the observatory. One could argue that having this HVAC was totally unnecessary and wasteful but for the purpose of my question please ignore that point and indulge me :grinning:

Here is my intention: On days where the observatory is hot I would like to precool for about 2 hours before shutter opening. The observatory is controlled by Interactive Astronomy’s SkyAlert. This concept is largely straightforward. However, there are evenings when the weather forecast is dismal and on those nights there would be no need to precool since the likelihood is that the shutter will remain closed all night. But how is this done? What is the “metric” to use to predict a “no work” night. My guess is that I could tap into OpenWeather API, to get a forecast for the night. If the forecast is pathetic (dense cloud cover/rain) there will be no precooling regardless of the dome temperature. So, I would not be using OpenWeather server to decide safety or shutter behavior. No! Rather it would be used just to tell the AC that precooling is not to occur since the observatory is likely to remain idle that night. After all, I don’t care if it’s too hot if I’m not going to image! I would still rely on SkyAlert to make the “safety” determination and to open the shutter or not. Though precooling would be based on dome temperature (or temperature differential) I wish to use some forecast metric to determine whether precooling is warranted regardless of the temperature threshold being reached. BTW, the telescope park position can be placed in such a position so that the AC output can be very close to the large CDK mirror.
So that’s what I am looking for: Just ideas.
FYI, the main reason I built the observatory with its own HVAC system was, for nothing else, working comfort. There are days (or nights) when the shutter is closed but I wish to do work in the observatory. It’s nice to cool it or heat it. Anybody who owns a metal dome know that they are literally ovens. (or refrigerators).
In summary (and more simply stated) I would like to automate activating the AC in the early evening to improve cool down time. But I would like to automate this not occuring on nights where the weather forecast makes imaging unlikely (to avoid waste)

Use a WAIT SAFE excluding the light conditions with a custom define offset and only activate the relay using Viking and Wait TIme to stop relay. After … use again WAIT SAFE with different offset to understand if open or not the things.

Thanks much Leo. Helpful.
Yet still wondering what paramete or metric would be that best method which provides a regional general entire night forecast. This is, of course, less a “Voyager” question and more a general astronomy management question

My suggestion looking also at others solution is to trust locally data from your station.

All the best