One Call API 4.0 is a unified weather intelligence API designed to give developers, digital products, and enterprise teams access to current weather, short-term forecasts, long-range daily outlooks, historical weather records, and official weather alerts through a single integration. Instead of combining multiple weather endpoints and datasets, users can request highly relevant weather information for any latitude and longitude from one product family built around a consistent response structure.
The API is built for applications that need both speed and depth. It supports immediate operational use cases such as current conditions and next-minute precipitation monitoring, while also enabling more advanced analytics with hourly and daily timelines that combine historical data with forecast data. This makes One Call API 4.0 suitable for real-time user experiences, operational planning, data analysis, and weather-driven business decisions.
One Call API 4.0 simplifies weather data access by consolidating multiple temporal layers of weather information into one coherent API product. With a single API key and a standard request model based on geographic coordinates, teams can access:
This combination helps businesses reduce integration complexity, shorten development time, and create richer weather-aware experiences across consumer, commercial, and industrial use cases.
1. Current Weather in Real Time
The API returns current weather conditions for a specific location with core meteorological parameters such as temperature, feels-like temperature, pressure, humidity, dew point, UV index, cloud cover, visibility, wind speed, wind direction, sunrise and sunset times, and weather condition descriptors with icons. This endpoint is useful for apps and services that need an instant snapshot of weather at a location.
2. Hyperlocal Next-Minute Forecasting
One Call API 4.0 includes a 1-minute forecast timeline for the next 60 minutes. This is especially valuable for products that need highly responsive precipitation monitoring and short-term decision support, such as mobility services, event platforms, logistics tools, outdoor consumer apps, and smart city solutions.
3. Intra-Day Forecasting in 15-Minute Resolution
For near-term planning, the API provides 15-minute forecast data covering up to 48 hours ahead. This supports operational decisions that need more granularity than hourly updates, including staffing, route planning, outdoor scheduling, field service coordination, and customer-facing forecast visualizations.
4. Unified Hourly Timeline Across Past and Future
One of the strongest differentiators of the product is its hourly weather timeline endpoint, which combines historical weather data going back 47+ years with forecast data extending 48 hours ahead. This allows users to work with one consistent hourly dataset for retrospective analysis, benchmarking, anomaly detection, and forward planning without switching between separate products.
5. Unified Daily Timeline Across Past and Future
The daily timeline endpoint brings together long-range historical weather data and forward-looking daily data in a single structure. It spans 47+ years of history and extends into future daily coverage, including short-range forecast data and long-range daily outlooks up to 1.5 years ahead. This is especially useful for trend analysis, seasonal planning, demand modeling, agriculture, insurance, and climate-sensitive business forecasting.
6. Official Weather Alert Access
The API includes alert references in weather responses and supports a dedicated alert endpoint for retrieving detailed warning information issued by national agencies. Alert payloads include the alert ID, source, event name, start and end timestamps, and full descriptive text. This helps teams enrich their products with actionable warning content and improve user safety and operational awareness.
The main product version includes the following standard endpoints:
In addition, the specification outlines standby endpoints for teams that may need separated forecast-only or history-only access patterns:
This structure allows the product to serve both simplified integration needs and more advanced data retrieval strategies.
One Call API 4.0 uses a straightforward request model centered on geographic coordinates. Core request parameters include:
lat and lon for location targetingunits for selecting measurement systems such as metric or imperiallang for localized human-readable weather descriptionsappid for authenticationstart for defining the starting timestampcnt for controlling the number of records returnedThe response format is consistent across endpoints and includes location metadata such as timezone and timezone offset, which makes downstream handling easier for developers building dashboards, apps, automations, and analytics pipelines.
The API is designed to support a broad range of product and platform experiences. Developers can build location-based weather widgets, travel and mobility tools, operational dashboards, enterprise analytics, forecasting engines, and alert-driven workflows on top of a single weather interface. Standardized response patterns and navigation links such as prev and next also make it easier to page through time-based datasets where applicable.
Because the same product covers current, forecast, historical, and alert data, teams can reduce fragmentation in their weather stack and maintain a cleaner architecture across frontend, backend, and data workflows.
To keep responses predictable and efficient, each endpoint has defined limits on the maximum number of records returned per request. For example:
This model gives users control over how much data they request while helping ensure manageable payload sizes and consistent API behavior.
One Call API 4.0 is well suited for:
One Call API 4.0 is a comprehensive weather data product that brings together real-time conditions, high-resolution short-term forecasting, historical weather depth, long-range daily coverage, and official alert data in one flexible API. It is built for teams that need more than a simple forecast feed and want a single, scalable interface for weather-aware applications, analytics, and decision support.