There are many free and informative data about the real-time weather forecast. Here are some free Weather APIs to try into your projects.
Weather radar data, worldwide. Tile server and single radar images.
7Timer! is a series of web-based meteorological forecast products, mainly derived from the NOAA/NCEP-based numeric weather model, the Global Forecast System (GFS).
APIXU weather and geolocation API provides you with access to get real-time, future and historical data ranging from weather, sports, astronomy, currency and much more for your website or application for any IP address, city, zip or geo point in the world.
NOAA Climate Data
Climate Data Online (CDO) provides free access to NCDC's archive of global historical weather and climate data in addition to station history information.
Real-time UV Index Forecast
MetaWeather is an automated weather data aggregator that takes the weather predictions from various forecasters and calculates the most likely outcome.
Air quality and weather data
Access current weather data for any location including over 200,000 cities
Get up-to-date weather information for any location, including 10-day forecast, wind, atmosphere, astronomy conditions, and more.
With our Weather API you can retrieve current weather observations from over 45,000 live weather stations, historical weather data for the past 10 years from our archive of more than 120,000 stations, and highly localized weather forecasts for any point on the globe using the world's most trusted weather models!