OpenWeatherMap API: Current Weather & Forecast Data

Overview

OpenWeatherMap offers a comprehensive collection of APIs designed to provide weather data for various applications. Since its founding in 2012, the platform has focused on delivering accessible weather information, ranging from current conditions to multi-day forecasts and historical data. It serves as a resource for developers looking to integrate meteorological data into their web services, mobile applications, and IoT devices. The APIs are built on a RESTful architecture, making them compatible with various programming languages and development environments.

The platform is particularly well-suited for small projects and prototypes due to its generous free tier, which allows up to 1,000,000 API calls per month for popular endpoints like Current Weather and 5-day Forecasts, with a rate limit of 60 calls per minute. This makes it a viable option for educational purposes, personal projects, and startups in their initial development phases. For applications requiring higher call volumes, more granular data, or specific features like hourly forecasts for extended periods or advanced weather maps, OpenWeatherMap provides several paid subscription plans.

Key offerings include the Current Weather Data API, which provides real-time conditions for any specified location, and the 5-day / 3-hour Forecast API, which delivers weather predictions at 3-hour intervals for up to 5 days. For more detailed forecasting, the One Call API consolidates current, minute-by-minute, hourly, and daily forecasts into a single API call, reducing the complexity of data retrieval. Historical data is also available, allowing developers to retrieve past weather conditions for specific dates and locations.

Beyond raw data, OpenWeatherMap also provides Weather Maps APIs for visual representations of weather phenomena like temperature, precipitation, and clouds, which can be overlaid on custom maps. The Geocoding API assists in converting city names or zip codes into geographical coordinates, simplifying location-based queries. The developer experience is generally considered straightforward, with clear documentation and consistent API responses, facilitating efficient integration into diverse applications.

Key features

• Current Weather Data API: Provides up-to-date weather conditions including temperature, humidity, pressure, wind speed, and weather descriptions for any geographic location (Current Weather API documentation).
• One Call API: Offers a consolidated endpoint for retrieving current weather, minute-by-minute forecast for 1 hour, hourly forecast for 48 hours, and daily forecast for 8 days, all within a single API call based on geographical coordinates (One Call API reference).
• Forecast API: Delivers 5-day / 3-hour weather forecasts, providing predictions for various parameters at regular intervals (5-day forecast API details).
• Historical Data API: Allows access to past weather conditions for specific dates and locations, useful for analysis, trend identification, and machine learning models (Historical Weather API information).
• Weather Maps APIs: Provides tile layers for various weather parameters (e.g., temperature, precipitation, clouds, wind) that can be integrated into mapping applications for visual representation of weather data (Weather Maps API documentation).
• Geocoding API: Facilitates the conversion between city names, ZIP codes, and geographical coordinates, which is essential for location-based weather queries (Geocoding API reference).
• Air Pollution API: Offers current and forecast air pollution data, including concentrations of CO, NO, NO2, O3, SO2, PM2.5, PM10, and NH3 (Air Pollution API docs).
• Global Coverage: Provides weather data for over 200,000 cities worldwide, ensuring broad applicability for international projects.

Pricing

OpenWeatherMap offers a tiered pricing model as of May 2026, starting with a free plan and scaling up to enterprise solutions. Details are available on the OpenWeatherMap pricing page.

Common integrations

OpenWeatherMap APIs are commonly integrated into various systems and applications due to their RESTful nature and wide language support. Developers often use cURL for testing and scripting, Python for data analysis and backend services, and JavaScript for frontend web applications. Specific integration examples include:

• Web and Mobile Applications: Displaying current weather conditions or forecasts directly within user interfaces. Examples include travel apps, smart home dashboards, and local news platforms.
• IoT Devices: Connecting sensors and smart devices to retrieve local weather data to trigger actions or display information, for instance, in smart irrigation systems or weather stations.
• Data Analytics Platforms: Incorporating historical weather data into business intelligence tools to analyze correlations between weather and sales, energy consumption, or agricultural yields.
• Gaming: Implementing dynamic weather systems in games that reflect real-world conditions or predetermined forecasts.
• Geographic Information Systems (GIS): Overlaying weather map tiles onto GIS platforms to provide an additional layer of environmental context.

Alternatives

While OpenWeatherMap provides comprehensive weather data, several other providers offer similar or specialized services. Evaluating alternatives often involves considering factors like data granularity, API capabilities, pricing structure, and specific feature sets.

• AccuWeather: Offers a wide range of weather data solutions, including specialized forecasts and historical data, often targeting enterprise clients with detailed reporting.
• Tomorrow.io: Known for its hyper-local, minute-by-minute forecasts and proprietary weather intelligence platform, suitable for applications requiring high precision.
• Weatherstack: Provides a straightforward API for current and historical weather data, emphasizing ease of integration and global coverage.
• AWS EC2 Weather Data: Although not a direct competitor as an API provider, some cloud platforms like AWS provide access to weather data through their services, offering an alternative for those already in the AWS ecosystem.
• IBM Weather Company API: Offers enterprise-grade weather data, analytics, and forecast services, often utilized in critical industries requiring high reliability and detailed meteorological insights, as detailed in their developer toolkit documentation.

Getting started

To begin using the OpenWeatherMap API, developers typically need to sign up for an account on the OpenWeatherMap website and obtain an API key. This key is used for authentication in all API requests. The primary method for interacting with the API is through standard HTTP GET requests. Below is a basic example using cURL to retrieve current weather data for London.

curl "https://api.openweathermap.org/data/2.5/weather?q=London&appid={YOUR_API_KEY}"

Replace {YOUR_API_KEY} with the actual API key obtained from your OpenWeatherMap account dashboard. The response will be in JSON format, containing details such as temperature, humidity, wind conditions, and a weather description.

For Python developers, the process involves making an HTTP request and parsing the JSON response:

import requests

API_KEY = "{YOUR_API_KEY}"
CITY = "London"
URL = f"https://api.openweathermap.org/data/2.5/weather?q={CITY}&appid={API_KEY}&units=metric"

response = requests.get(URL)
data = response.json()

if response.status_code == 200:
    main_weather = data['weather'][0]['description']
    temperature = data['main']['temp']
    print(f"Current weather in {CITY}: {main_weather}, Temperature: {temperature}°C")
else:
    print(f"Error: {data['message']}")

This Python example fetches the current weather for London and prints a summary. The &units=metric parameter specifies that temperature should be returned in Celsius rather than the default Kelvin. Developers can consult the OpenWeatherMap API references for detailed endpoint documentation and available parameters.