Thermostat ran off hourly weather forecast

Hello. I am a newbie and know little about this.

I am wanting to make a thermostat to control a special heating unit. Is there a way to look at a hourly weather temperature forecast online for my area? Then take that hourly temperature forecast data along with other data such as inside temp, time of day, etc to control a heating unit.

For example, if its winter, and its a mild day outside not calling for any heat but the weather forecast shows the temperature dramatically falling that evening. I would like to read that to turn the heat on a few hour early.

Our heating system is very slow to catch up but if I can make a thermostat to turn the heat on early before it get to cold it wont be playing catch up on the temperature.


There are API's that allow you to get weather dat and import the data into your app. You might want to check out weather underground. I think google, also, has a weather API.

I use ESP32's. I have a weather station in my backyard. From my website I can read the weather station data and adjust my HVAC system to either heat more or cool more. I have home humidifier that I can set the home humidity level from my web site.

There are numerous services that offer weather data. I use one to get current conditions but I believe it offers forecasting too. I can't recall which one I use because such things have a habit of retiring their free tier and in consequence, I am on my third.

I was using weather underground for a while, but they were sold to IBM I think and the free service was revoked. Now, I'm using openweather, we'll see how long that lasts :thinking:

I also use a NOAA service to get current conditions from a nearby airport. I don't know if they have forecasting included though.

okay, so how exactly do you go about using that data in a arduino?

I guess I need a temp sensor inside, and it needs to be the main sensor. no matter what the inside temp sensor calls for heat then it turns on heat, it it is above set point then it turns off heat UNLESS the forecast calls for a certain % drop in temp a certain number of hours away???

Does that sound correct?

More or less. Usually, such systems use some amount of hysteresis to avoid rapid cycling of the heater when it is close to the set point.

You might simply want to raise the set point if there's colder weather ahead.

It might be simplier to build an optimiser that brings in the heating earlier/later depending on the outside temperature . I would do that first before getting more clever and see how that works .
You really need to model the dynamics of the house - heat output , solar gain, heat loss , time of day .
Even then, depending on your heating system the over or undershoot from your desired temperature depends on the heat loss at that time ( ie outside temp ) and the stored heat in your heating system ( assuming the heating is on /off control )

If you bring the heating on early whilst it’s warm outside , but later cooler it will over shoot and get the house too hot before it gets cool and waste energy.
You could look at just running with a lower set point when no one is in or at night .

Lots to play with , start simple

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