The documentation for Accuweather forecast API service.
MetaWeather is an automated weather data aggregator that takes the weather predictions from various forecasters and calculates the most likely outcome. The thinking is that the combined knowledge of the forecasters will produce a better prediction. Free API but drop them an email to let them know if you're going to be hitting their service more than once a minute.
Current weather, global climate reports and more. Free. Temperature, wind, humidity, cloud cover, precipitation, and more.
REST API: https://www.troposphere.io/developer
An air quality monitoring network built on a new generation of Internet of Things sensors. Using a new generation of laser particle counters to provide real-time measurement of PM1.0, PM2.5 and PM10. PurpleAir sensors are easy to install and only require a power outlet and WiFi. They use WiFi to report in real time to the PurpleAir map. Sells air quality sensors that are pretty expensive. Don't know if it'd be possible to upload data from other kinds of sensors.
Account creation requires authenticating with a Google account only.
They have a JSON API but it's read-only and just a straight dump from their database: https://www.purpleair.com/json
https://www2.purpleair.com/community/faq#hc-access-the-json
There is also a Thingspeak API: https://www2.purpleair.com/community/faq#hc-thingspeak-api
They also seem to have a REST API but you need an API key and ChannelID. Not a big deal, really.
I don't know if this service is suitable for my purposes.
Software that simulates weather crawls and bulletins from the 80's and 90's. Show weather conditions and weather almanac data just like the early days of cable television. Customizable data layouts and crawl messages. Written in C++; nobody's perfect. Still tries to be as lightweight and simple as possible.
A worldwide, real time, community collaborative lightning location network.
Might be an API. Data could be useful.
A site that tracks tornados in the US. Notes their severity and location.
NWS Homepage of the National weather Service. Offers multiple kinds of weather forecast feeds - RSS and XML. API You can dig around to find the kind of weather data you're looking for; you'll probably have to go to the sub-sites linked
website for a project that teaches you how to build a weather monitoring station using a raspi and a couple of sensors. citizenscience environment howto FOSS
An online open and crowdsourced weather service. People set up automatic weather stations (which are fairly cheap) and contribute measurements that are aggregated into forecasts. Has an API so you can pull data out of it as well as contribute it: http://openweathermap.org/appid Free accounts are, of course, limited in several ways. You can also get weather maps of various kinds from the service to visualize the forecast data. Forecast data is in XML, JSON, and HTML formats.