# General information

AccuWeather's Historical API delivers archived daily weather observations going as far back as **January 1, 1990**, with new days added continually. Useful for forensic analysis, climate trend studies, insurance verification, and any application that needs reliable historical context.

Coverage spans **85,000+ global locations** with **15+ derived parameters**, including AccuWeather's patented **RealFeel®** and **RealFeel® Shade** temperatures.

Data is available in **more than 200 [languages and dialects](/developers/languages)**, in both **JSON** and **CSV** formats.

→ See the [Historical Guide](/developers/historical/guide) and [Parameters](/developers/historical/parameters) for endpoint details and request patterns.

## Day boundaries

By default, daily records cover the **meteorological day** (7:00 AM to 7:00 AM local time) — aligned with standard observation practice.

Pass `calendar=true` to retrieve data for the **calendar day** instead (midnight to midnight local time). Use this when aligning historical data with business or consumer day-based reporting.

## Time zones

All data is in **local standard time**. Queries must be placed based on local time for the requested LocationKey.

## Requirements

Historical API searches require a **LocationKey**. Use the [Locations API](/developers/locations/guide) to look one up.