The Short Answer
A future version of the app will add support for using your PWS station's live data, in addition to the current forecast data.
However, you'll need to have an API key for your PWS. Access to PWS data is tightly controlled by the Wunderground. As a PWS owner, you can access your own PWS realtime data for free, but not other PWS station data. This kind of access is called "API" access, meaning it's a way for one piece of software (the wunderground servers) to talk to another piece of software (the app).
After we finish the PWS feature for the app, you'll be able to enter your API Key into the app on your phone or tablet. Your device will then act as a relay, retrieving the PWS data (for free because you're the PWS owner), and then relaying it back to our app's cloud servers to be converted into a projection of indoor conditions (temperature and humidity) using our custom algorithm, and then the result displayed on the screen. This process will also apply your personalized recommendations for Off/Cool/Fan mode, using your personal temperature and comfort settings from your Settings tab.
Wunderground aka "The Weather Company", an IBM subsidiary, sells access to the PWS data for very steep fees, starting at $500/month, which is too expensive for the app developer to pay at this time.
How Do I Get An API Key?
You can get your PWS' "API Key" from Weather Underground, see: Wunderground > My Profile (log in) > My Profile(again) > My Devices > 'API KEYS' tab
It will consist of 32 letters and numbers (hexadecimal), similar to: 3ed58e1590d4c9391927740cf9f76409 (not real)
The app will also need your public PWS station name, something like KCAPALMS00. The station name is listed on the Wunderground 'My Devices' tab in the ID column.
Note: there is another column on 'My Devices' called "Key" which is not relevant for API access. (That is the password your PWS uses to talk to Wunderground, so keep it private.)
I'm Lost, What's a PWS and Why Would I Want One?
If the short answer above reads like ancient greek...
Sorry!
Keep reading to learn how PWSs and weather forecast data are related (or not!) and what it all means when put together.
What is a Personal Weather Station (PWS) ?
This is a privately owned weather station you can purchase and install outdoors which uses an array of sensors to measure your realtime weather conditions: temperature, humidity, wind speed, rain, etc.
Weather Underground has an overview of the concepts involved in their Personal Weather Station Network
They range in price from $120 USD for a basic (but still good) unit, and can cost upwards of $500 USD for the more advanced ones. The developer uses a system made by Ambient Weather LLC, a company based out of Arizona.
Ambient Weather's current entry-level weather station looks pretty solid, and less than $150 at the moment: Ambient Weather WS-1965 (amazon). We haven't used this model, as the developer has a much older model, but the specs look great and it looks like a more-evolved version of our WS-1400 system. A nice benefit of the WS-1965 model is that it doesn't require a separate base-station device to connect to your home network; it has WiFi built-in. (FTC Disclaimer: the links to products here generate an affiliate commission if purchased the product via this link. Our non-disclaimer: Ambient Weather makes great products, and we have direct experience using an older model for the past 7 years continuously, through 124° heat spikes and generally ridiculously hot summers. We replace the AA-rechargable batteries regularly once a year, and have had zero problems.)
A more high-end Ambient Weather station features sensors with no moving parts. This feels like magic. I think it's the good kind. If you're looking for the most sleek, modern and capacious unit, then I recommend Ambient Weather's WS-5000 model. It's a gorgeous design, but also quite pricy. We wish we had more experience with other vendors, but Ambient Weather has been solid for so many years, so we can only give them the highest marks.
Many stations are solar powered, equipped with rechargable batteries that store enough charge to continue operating overnight and through many cloud days.
Most weather stations are also wireless, either by transmitting their data over 433MHz or 915MHz radio frequencies to a "base station" plugged into a home network, or over regular WiFi (2.4GHz or 5GHz) to your wireless router. The data is then sent to the manufacturer's cloud servers, and sometimes the station can send the data to a "PWS receiver," usually Weather Underground's systems. Commercial (i.e. expensive) and official weather agency stations can even use a cellular modem, for inaccessible or somewhat remote locations.
That PWS sensor data is then usually shown for the public to see on the Wunderground website¹, and it's used to help provide community-gathered raw data for commercial companies to use to enhance the local weather forecasts they receive from our National Weather Service (NWS) in the USA, and other meteorological agencies around the world.
If you looking at a PWS that doesn't have a way to send its data over the internet, then I'm sorry, that's not the kind of PWS we're talking about here. There are some weather stations that have a display console and are technically wireless, but if they don't send their data up into the internet, then it's not possible to use that station with any phone or tablet app.
- There are additional commercial "networks" for PWS data, like pwsweather.com that aim to provide a competing experience.
Forecast "Now" vs. Observed "Now" In Weather Apps
It's probably surprising to learn that most weather apps don't show an actual measurement when they display your "Current Weather". They show your forecast for "Now" for your location.
You might've noticed that some weather app is reporting that it's 80°F out, but the thermometer outside your window is showing 68°F. It's not common for very large differences between the immediate forecast and actual weather, but... Every forecast is still just an approximation, even when it's for right "now".
What does "now" even mean?
Without getting too metaphysical, from a data perspective: "now" actually means: the most recent forecast that projects "zero time ahead". It's sometimes called a "zero-th hour" (or "forecast hour 0") because it's generated as the first of a sequence of datasets representing time marching forward from the weather models, coming out of the supercomputers that the NWS and other government weather agencies operate.
For a very long time, those forecasts were an hour-wide "window". Nowadays, due to advances in the NWS and NOAA's technology for the US, we have forecasts for 15-minute intervals! "Now" is suddenly a lot more complicated...
How often a new forecast is produced makes a big difference: Currently, NWS/NOAA updates the HRRR model's forecasts every hour. Even though it's sliced up into 15-minute intervals, there are times when the most recent forecast was generated 59 minutes ago. "Now" is looking a lot more like "Then" the more you look into it!
Depending on where you are in the world, and which government weather forecast data you're using, it's possible you might have a "Now" forecast that is just a few minutes old (hurrah!) or, in some locales with less meteorology infrastructure, as much as 6 hours old.
It feels strange that a forecast is made for the present moment, and not just the future, but this is how it works, because there are actually surprisingly few officially supported weather observation stations operated by government agencies. The "hour 0" forecast incorporates the most recent station data and the complex weather models then fill in the gaps as best they can, to try and paint a picture of the "initial conditions" for the supercomputers to use for their forecasting. "Complicated" seems like an understatement.
Those official weather observation stations use extremely expensive and precise scientific equipment, and require periodic maintenance and physical security from unauthorized access. It's not cost-effective to run them everywhere, so they're often found at municipal facilities like airports and town halls.
So, "Now" is sometimes "Then" and it's best when it's fresh!
How Does The Evaporative Cooler App Get Its Weather Data?
The app is powered directly by the raw forecast data (GFS 0.13, 0.25 and HRRR models) produced by the supercomputers at the NWS/NOAA in the USA, ICON models from the DWD/Germany, GEM models from the CMC/Canada, Metno's models and additional air quality data from the ECMWF's ADS models from the European Union. A special piece of server software called Open-Meteo allows this data to flow into a system that makes it very easy to combine and overlay the various forecasts in such a way to provide global coverage, using the "best" or preferred models based on coverage in both space and time (how far ahead the model goes).
This system provides super fast updates, within minutes of the new data becoming available from the supercomputers. For the hourly HRRR data updates, this means a brand new forecast for "hour zero" is available almost immediately. This "freshness" translates into more responsive weather data, as the observational data updates, as the forecast for "now" and "now plus 15 minutes" is refreshed and so on.
Ultimately, though, it's still an "hour zero" forecast. That's why a PWS can open a new window for us.
How Would PWS Data Help Me Run My Swamp Cooler?
The sensor array in a PWS is collecting real observations, real measurements, for your exact location, and at a very high refresh rate (high collection frequency). You can't beat the accuracy and relevance of a thermometer at your home, compared to any forecast. Except maybe to have two thermometers to cross-check them... But that's going overboard. Perhaps.
The goal then is to use your PWS's realtime measurements of temperature and humidity, to run those numbers through the algorithms we've developed for the app to project your swamp cooler's realtime indoor temperature and humidity.
Aside from one caveat: this does work! The algorithm for projecting indoor swamp cooler conditions was developed using realtime data from a PWS' sensors at the developer's home in Palm Springs. The data from a 2 year period helped refine a (proprietary, for now) set of equations that operate at the heart of the software that drives the app. Using realtime PWS weather data with those equations produces realtime projections that almost perfectly match sensor data gathered at the output fan of the swamp cooler. The bottom line is: PWS data are real measurements, real observations, versus forecast data which comes from a model and has drastically less fidelity and resolution.
Who Owns PWS Data?
Like your last or current relationship... It's a complicated story, and there's probably some drama involved!
The good news: If you own a PWS, you probably will have free access to your own station's data. Depending on the terms of service of the manufacturer, and the flexibility of the PWS's built-in software, you might have the ability to even siphon off a copy of that data to other systems (third party or your own server) by entering additional destinations for the PWS to direct its sensor data.
The bad news: Some PWS only support sending the data to one destination, either the manufacturer alone, or Wunderground alone, or sometimes both, but not a third party.
Like we said, it's complicated...
Technically, you own the device and the data when it's collected. But once the data is sent to the manufacturer or Wunderground, you're bound by the rules in their Terms of Service. They're not required to provide the data back to you. In fairness, it costs them money and resources to even recevie a copy of that data, store it, and then process it into a form that they can then provide back to you within a web page or their own app... so it's something of a cost-center for the manufacturers.
Adding even more complexity is that some devices will send the data to both Wunderground and the device manufacturer's cloud servers. In this case, the manufacturer operates an entirely separate data processing service, and has their own separate method for accessing "your" station's data. It's usually free to access your own PWS' data, but not other stations.
For a long time, Wunderground provided free access for PWS data to the world, letting anyone get the data for any PWS located anywhere... All for free... Oh the glory days!
This changed on March 1, 2019 when Wunderground terminated the free "public API." In its place they offered an "owners only" access plan, so individual PWS owners can retrieve their station's data, for free, and subject to certain (reasonable) limits, to prevent their operating costs from ballooning.
As the ownership of Wunderground has changed several times- from "The Weather Channel Companies" in 2012, then renamed as "The Weather Company", acquired by IBM in 2015, until most recently in 2023 when it was sold to the private equity firm "Francisco Partners."
We can only say about the future of Wunderground and their support for PWS data: it's a partly cloudy forecast with a chance of rain.
So, What Now?
Until anything else changes however, the PWS "owners API" is still working, and we're working on adding support in a way that fully complies with the terms of service for accessing that API, so PWS owners can get an edge on their swamp cooler realtime recommendations.
We're data-addicts here, so we're always looking for new sources and methods for getting the best weather data, and there are a few more options we're thinking about:
- Allowing PWS owners to opt-in to sharing their station's data to benefit others in the neighborhood (in a secure and privacy-preserving way)
- Incorporating official NWS observation station data (e.g. airport stations) to generate corrective factors to help adjust the "forecasted now" to better match the "recently observed almost-now" data.
- Requesting access to NWS' crowdsourced observation stations.
- Producing a Raspberry Pi OS image file for use with a customer-provided RPi model 3, 4 or 5 and a USB RTL-SDR RF receiver, to directly receive station data from 433/915 MHz and then transmit a feed to both the swamp cooler app servers, and as many PWS receiver destinations you prefer. This is probably too ambitious at the moment, but it's a setup the developer uses and works quite well.
- Experimenting with the AI GraphCast made by Google, to see if it might have better "hour zero" corrections for realtime weather status.
IF you have ideas you'd like to share, send them our way: support@TenthLight.com