Aemet Pricing: Free API for Spanish Weather Data (2026)

Pricing overview

Aemet offers its Open Data API as a free service, providing developers with access to a range of meteorological information for Spain. This model eliminates direct monetary costs, making the API accessible for various applications, from academic research to public service tools and personal projects. The primary cost consideration for users of the Aemet API revolves around adherence to its defined rate limits, which govern the volume and frequency of data requests. Users must register on the Aemet website to obtain an API key, which authenticates requests and ensures compliance with these usage policies. The API's focus on Spanish meteorological data positions it as a specialized resource for developers requiring detailed regional weather information.

The free pricing structure supports Aemet's public service mission, enabling widespread integration of official meteorological data. While there are no subscription fees or per-request charges, developers need to implement proper caching strategies and error handling to manage the rate limits effectively and prevent service interruptions due to excessive requests. This approach contrasts with many commercial weather APIs, which typically employ tiered pricing based on request volume, features, or data granularity. For instance, platforms like OpenWeather and AccuWeather offer free tiers but often gate advanced features or higher request volumes behind paid subscriptions, as detailed in their respective developer documentation for OpenWeather API access and AccuWeather API plans.

Plans and tiers

Aemet's API operates under a single, free tier. There are no distinct paid plans, premium subscriptions, or feature-based tiers. All available data endpoints and functionalities are accessible to every registered user without charge. This unified approach simplifies the decision-making process for developers, as they do not need to evaluate different service levels or pricing structures. The core offering includes access to weather forecasts, climatological data, and meteorological observation data, which are fundamental for applications requiring current and historical weather information for Spain.

This model is particularly beneficial for non-profit organizations, educational institutions, and independent developers who might face budget constraints when integrating external data services. The absence of complex pricing matrices or usage-based billing means that developers can focus purely on integrating the data and managing their application's request patterns within the specified limits. Unlike commercial APIs that might offer enterprise-grade support or guaranteed uptime through higher-tier plans, Aemet's free service implies a standard level of support and availability, typical for a public sector open data initiative. Developers are encouraged to review the official Aemet API documentation for the most current information regarding data availability and usage guidelines.

Free tier and limits

The Aemet API provides a comprehensive free tier with specific rate limits designed to ensure equitable access and system stability. Users can make an unlimited number of requests in total, but these requests are subject to a maximum of 300 requests per minute and a maximum of 10 requests per second. These limits are applied per API key, meaning individual applications or users are bound by these constraints.

Understanding these limits is crucial for developers:

• Requests per minute (RPM): This limit dictates the total number of API calls that can be made within a 60-second window. Exceeding 300 requests in any given minute will result in subsequent requests being throttled or rejected until the next minute starts.
• Requests per second (RPS): This more granular limit prevents bursts of requests, ensuring that the server isn't overwhelmed by simultaneous calls. A maximum of 10 requests can be made within a single second.

To effectively utilize the Aemet free tier, developers should implement client-side rate limiting and caching mechanisms. Caching frequently requested data can significantly reduce the number of direct API calls, helping applications stay within the specified limits. For example, if an application displays the current weather for a specific city, caching this data for a few minutes before making a new request can optimize API usage. Implementing exponential backoff for retries in case of rate limit errors is also a recommended practice, as described in general API best practices by Google's API client library guidelines.

The free tier includes access to a wide array of data points, such as current observations, short-term and long-term forecasts, and historical climatological data for various locations across Spain. This extensive data availability within the free tier makes Aemet a valuable resource for developers focused on Spanish-specific weather applications without incurring costs associated with data access.

Real-world cost examples

Since the Aemet API is entirely free, there are no direct monetary costs associated with its use. The 'cost' in real-world scenarios translates primarily to development effort in managing rate limits and ensuring efficient data retrieval and caching.

Scenario 1: Small Local Weather App

A developer creates a mobile application displaying current weather and a 7-day forecast for 5 major Spanish cities. The app updates data every 15 minutes. For each city, it makes two API calls (one for current data, one for forecast). This totals 10 requests per update cycle (5 cities * 2 requests/city). Over an hour, this would be 40 requests (10 requests * 4 updates/hour). Over a 24-hour period, it's 960 requests (40 requests/hour * 24 hours). This usage is well within the 300 requests per minute limit and the 10 requests per second limit, incurring no monetary cost.

Scenario 2: Agricultural Monitoring System

An agricultural system monitors weather conditions for 50 distinct farm locations across Spain, updating specific parameters (temperature, humidity, precipitation) every 30 minutes. Each update involves one API call per location, totaling 50 requests per update cycle. Over an hour, this is 100 requests (50 requests * 2 updates/hour). Over a 24-hour period, this becomes 2,400 requests. This remains well within the 300 requests per minute threshold (100 requests spread over 60 minutes) and the 10 requests per second limit, remaining free of charge.

Scenario 3: Real-time Public Information Display

A public display system in a busy train station needs to show frequently updated weather for 10 key destinations in Spain. It updates every minute. Each update requires one API call per destination, totaling 10 requests per minute. Over an hour, this is 600 requests. While 10 requests per minute is well within the RPS and RPM limits, a system updating 10 destinations every minute would consume 600 requests per hour. This is manageable, as 10 requests per minute is far below the 300 RPM limit. The system would also incur no monetary cost, requiring only diligent adherence to the rate limits.

These examples illustrate that for typical application usage, the Aemet API's free tier is robust enough to support significant data consumption without any financial burden, provided developers implement appropriate request management and caching strategies.

How the pricing compares

Aemet's free pricing model stands out when compared to many commercial weather APIs, particularly for applications focused exclusively on Spanish meteorological data. The primary distinction lies in the absence of tiered subscriptions, usage-based billing, or premium feature unlocks.

Here's a comparison with leading alternatives:

While alternatives like OpenWeather, AccuWeather, and Tomorrow.io offer broader global coverage and advanced features, their free tiers are typically more restrictive in terms of daily request limits and available data types. To access higher volumes or specialized data, users must transition to paid plans. Aemet, by contrast, provides its full suite of Spanish meteorological data within its free, rate-limited model, making it a highly cost-effective solution for region-specific applications. For developers whose projects are confined to Spain, Aemet often presents a financially superior option, provided the rate limits are sufficient for their operational needs.