[RNCTX]

I get that people like to play with hardware but for practical purposes, there are public APIs with airport weather station data that anyone can use, published at 5 minute intervals (typically).

Considering the data they output must conform to aircraft avionics parsers that are sometimes decades old, they are unlikely to ever change or go away. Since the weather observations are required for IFR flight, the FAA is quick to repair them when they break, too.

Whatever you can build with hobbyist hardware it won't compare to the airport's equipment.

https://www.aviationweather.gov/dataserver

[joshvm]

Lots of reasons why you might want more local though. My local airport is more than 10km away (but there are other monitoring stations). Pilots and controllers assume some uncertainty because even within the airport perimeter there will be temperature and wind variation, but they will be in-calibration which is the main advantage. Controllers often rely on pilots to make reports if conditions differ to what the airport is recording, so it's not always considered the absolute truth.

At home, for example: more accurate irrigation control based on local rainfall, greenhouse control, microclimate variations (which can be significant if you live in a hilly or mountainous region), observatory control for astronomers etc. There are lots of reasons why your local conditions could vary considerably from the airport, but you do need to put some effort into enclosures to avoid biases from solar radiation. You can also add other sensors like buried temperature sensors to monitor the soil, cloud cover, etc.

Microclimate is significant. If you live in a city, you'll likely have urban heating effects. If you live up a hill, you will have significantly different measurements to an airport in a valley. Anyone who's been hiking knows that you absolutely need local observations to assess conditions (eg from a hut). Though this is more for illustration, if you're hiking there are normally special weather services for common routes (Austria has a nice site for this I think).

The Met Office runs an API where you can contribute your own measurements [1]. Sites are rated based on quality of instrumentation - note that the gold standard here could be a calibrated mercury thermometer in a Stephenson screen, nothing special. Calibration is key.

These simple weather stations can also be used indoors as cheap multi room thermometers. You can pair them with air quality, gas and particulate sensors. Also a nice exercise in mesh/multi sensor networking.

[1] https://wow.metoffice.gov.uk/

[RNCTX]

Yes, I should have qualified that the airport API thing is much more practical in the US, I suppose, since we spend more on aviation than other countries.

Our government since WW2 has subsidized any city which wants an airport so they can have one.

I just took a look at the Dallas, Texas airspace as an example and there are 14 weather stations within the ring defining the metro area's restricted airspace. It looks like the airspace around London-Heathrow has 3.

[joshvm]

Here you'd probably want to use local automatic weather stations (AWS), which are a superset that includes major airports. There are lot more of those around London than just Heathrow. I imagine NOAA has a similar setup.

https://www.metoffice.gov.uk/research/climate/maps-and-data/...

I'm not sure if the CAA and Met Office share stations though. Airports often have more specific instruments like ceilometers to give measurements of cloud layer height, while AWS might have more cliamtologic things like pyranometers for sunlight hours.

[billfor]

I live in the US and use my local weatherstation to control my basement dehumidifier and decide whether or not to turn the thermostats. The airport is about 10miles away but actually doesn't have all of the data that I need, such as soil temp, leaf moisture, and it's not very local to my specific house which has lots of trees and tends to deviate from the airport that is more exposed. I still use the airport data, but integrated with my own local data to get a better picture of what's going on.

[jrockway]

My understanding is that the FAA sites aren't as useful as they could be for weather forecasting. Apparently many sites are too close to the ground, so the temperature data and dewpoint data is unusable for mesoscale analysis. Sometimes the dewpoint is above the air temperature, for example, which is impossible. It doesn't really matter for air traffic, but it does matter for forecasting storms.

If you are interested in the wind direction or the height of the cloud bases, the aviation weather stations are OK. If you are interested in temperature data, you will have to look elsewhere. (Many states have observation sites designed for weather purposes. The Oklahoma Mesonet was the first, but other states have them too. Often these sites have very interesting information, like soil moisture and temperature, and temperatures at varying heights above the ground: http://www.nysmesonet.org/about/sensors http://www.mesonet.org/index.php/site/about/instruments)

[RNCTX]

Don't know where this criticism comes from but temp and dewpoint data absolutely matter for air traffic, because it determines cloud bases. If cloud bases are below the decision height for the instrument approaches into an airport, it's illegal for a commercial operator to depart from there (because they could not reliably return to the field in case of emergency after takeoff).

The standard data output of an FAA weather station is in degrees Celsius, however, there is no accuracy more than that.

[jrockway]

They measure cloud bases directly, with a laser-based sensor.

[asdff]

One practical example of this hyper local data would be for automatic gardening. In LA, the temperature can range 20 degrees in 10 miles on a given day. It can be cool and cloudy by the beach and hot and sunny by downtown. This makes Dark Sky the only weather app that is somewhat accurate in LA.

If you are gardening in LA, and you knew the hyper local wind conditions in your plot, the light level, and the ambient moisture, you could develop an automatic watering solution for your garden that is truly hands free in all operation and can be customized based on individual plants needs. Many existing auto watering systems use soil sensors that are known to corrode and need replacement, so if you can infer soil moisture content from other non corrosive means that would be much preferred. You'd probably want to use the soil sensors at least initially to get an understanding of the function between your weather data and the particular soil composition of a given plant, but then they wouldn't have to be continually replaced.

After the recent very hot and dry winds from the desert (normally wind comes west) killed off some of my more temperamental plants last week, I'm thinking about some sort of automatic solution like this.

[stormdennis]

That's what I was thinking. You need the data from elsewhere to know what's headed your way.

[RNCTX]

The only exception to that rule I would say is it might be useful to have your own lightning strike sensor if your nearest airport doesn't have one. Lightning strike data is highly local and time sensitive. You can learn a lot about which clouds a small airplane should fly through 'right now' and which ones you should not, just looking at lightning strikes.

Otherwise, your tax dollars are paying for those airport readings, use the data you're footing the bill for already, imo ;).