The Visual Crossing Weather platform is able to join and analyze both historical weather and weather forecast data from many sources. The cloud-based version of the product used by the Microsoft Excel Add-in includes both historical and forecast weather data loaded periodically from various data providers. This document describes the data that is currently available to users of our cloud-based weather products. (Please note that additional data options are available for customers who utilize an on-premises or custom cloud solution. For details on the data availability for those solution, please contact Visual Crossing technical support or your account team.)
Historical Weather Data
The historical weather data includes worldwide coverage based on the coverage generated by over 100,000 worldwide weather stations. These stations are not heterogeneous in their reporting and thus have varying reporting characteristics including differences in metrics and reporting schedule. In addition there are often multiple stations with range of any given location. Visual Crossing is able to use these historical reports to calculate a single set of weather metrics for any location based on the following algorithm:
Historical weather reports of nearby weather stations within 50km of the requested locations are analyzed. The three closest valid stations reporting data at the requested time and then considered. Their historical records are combined by way of a weighted mean - the closest station will have more weight than those farther away. The reporting times are also normalized to the nearest hour of the day and then adjusted, as necessary, for the reporting time zone.
Historical weather in the standard Visual Crossing cloud solution is currently available for 1999-2019. For older data the number of weather variables available and geographical coverage is less. This is especially true for data prior to 1999. Many stations, in particular prior to 2010, do not report hourly precipitation data. If a station did report a non-hourly interval of precipitation accumulation (such as three or six hours), Visual Crossing processes the data to calculate hourly-level records based on the best available data that is possible.
Forecast Weather Data
The forecast data is created from the output the weather service model runs that are calculated periodically by national forecasting agencies such as NOAA in the US. These models produce a grid based forecast composed of many thousands of small cells each covering a small geographic area.
Currently Visual Crossing updates the forecast twice daily and draws weather forecast information from two models:
The United States Gridded Forecast Model - This model covers the United States (including Alaska, Hawaii and some territories) and Southern Canada. Data is available up to a 7 days forecast and has a native resolution of 1km.
German Weather ICON Model - This model covers worldwide areas including Europe, South America, Middle East and Canada. Data is available up to a 5 days forecast and has a native resolution of 0.1 degrees at the equator.
Other national models with further geographic coverage are available for on-premises and custom cloud solutions.
Disclaimer: Please note that the information above is current as of this writing but is subject to change without notice. Visual Crossing reserves the right to alter sources, coverage, and data providers as needed to balance both optimally accurate and cost-effective availability. In addition, the data described above is obtained from various providers some of which may not be available at times. If you need guaranteed quality, availability, or geographic coverage, please contact Visual Crossing technical support or your Visual Crossing account representative.