OpenWeatherMap offers a generous Free Weather API. Their free tier includes:
- 60 Calls per minute.
- Current Weather Data.
- 5 day forecasts (3 hour interval)
- Access to the Maps API.
Analysis: While very generous in it's allowance of fairly high volume (86,400 calls per day for free is nothing to discredit), the free tier does not include access to historical data. They also do not allow free access historical weather data.
Apixu offers a Free weather api, but their offering is very limited.
- 10,000 calls per day
- 7 day forecasts (daily)
- 7 days of historical weather data access
- Current Weather.
Analysis: They only allow 10,000 calls per month. Which is only a fraction of what Weatherbit, and OpenWeatherMap offer. They do, like Weatherbit, offer the ability to get access to a limited range of historical weather data on their free weather api.
Weatherbit offers a free Weather API with a similar structure to other providers, as well as more advanced API features to paying users. They include up to 500 calls per day, trial access to many useful features such as air quality, agricultural weather data, and energy sector specific information such as solar radiation.
Unlike other providers, Weatherbit sources precipitation, and cloud cover from satellite data as well as radar. This gives Weatherbit a significant advantage in areas with limited station coverage. See their recent article on the limitations of station based precipitation for more information.
In summary, features of Weatherbit's free Weather API include:
- 500 API calls per day.
- Trial access to features such as air quality, historical weather, and more.
- 48 hour/hourly weather forecasts.
- 16 day/daily weather forecasts.
- Current weather data.
Analysis: Unlike Openweathermap or Apixu, Weatherbit offers current weather data, daily, and hourly forecast API(s) in one package. Additionally, Weatherbit has a higher degree of accuracy in regions with few reporting weather stations due to it's use of radar datasets.