A TMY, or Typical Meteorological Year, is a collation of historical weather data for a specified location for a one year period. The dataset is derived from a multi-year time-series specifically selected so that it presents the unique weather phenomena for the location, and provides annual averages that are consistent with long term averages. All TMY files contain exactly 8760 rows of data, each corresponding to an hourly period in an ‘average’, or ‘typical’ year. TMY data is frequently used by solar engineers, as a data input to energy system simulations.

Solcast offers two variants of TMY: Basic (P50 only) and Extended (P50, P75, P90, & P95). See details on the Solcast pricing page

TMY data specifications

Pxx (Probability of exceedance)	Basic TMY	Extended TMY	Available on request
	P50	P50, P75, P90, P95	Pxx
Coverage	Global, except for ocean and polar regions
Spatial resolution of satellite data	1-2 km
Time granularity	60 minute
Timespan of database used to generate TMY	January 2007 to 7 days ago
Parameters	Global Horizontal Irradiance (GHI, W/m2) Direct Normal Irradiance (DNI, W/m2) Diffuse Horizontal Irradiance (DIF, DHI, W/m2) Temperature (TEMP, °C) Wind Speed (WS, m/s) Wind Direction (WD, °) Relative Humidity (RH, %) Surface Pressure (AP, hPa) Precipitable Water (PWAT, kg/m2) Snow Depth (SWDE, cm) Dew Point (DWPT, °C)
Files provided	Solcast standard CSV PVsyst SAM TMY3
Time zone	UTC (default for Solcast) Longitudinal (default for SAM, PVsyst, TMY)
Database update frequency	Daily (recent months are considered in TMY scenario)
Access method	Data can be ordered and downloaded via the Solcast API Toolkit
Download wait time	Typically 1 to 9 minutes