This page supplies both typical (most representative of a span of years) and historical (single year) weather data for 86-127 and 127 California weather stations, respectively.

Typical Weather Files: Three different typical year weather files are presented, each representing a different span of years.

• CZ2010 typical year files span 1998 through 2009 (a 12 year period of record) and were the standard weather files adopted by the California Energy Commission for Title 24 compliance calculations from 2010 through 2022. There are 86 CZ2010 files. As required by the California Energy Commission, the CZ2010 use statewide “typical months”. Read More
• CZ2018 typical year files span 2006 through 2017 (a 12 year period of record) and represents a more recent 12 year span of time than CZ2010. It should be noted that (1) CZ2018 includes the same 127 locations as the historical weather data, (2) uses location-specific “typical months”, and (3) “2018” refers to the year of creation, rather than the Title 24 version. These files are also sometimes referred to as CALEE2018. Read More
• CZ2022 typical year files span 1998 through 2017 (a 20 year period of record) and were adopted by the California Energy Commission for Title 24 Version 2022. Like the CZ2010, CZ2022 uses statewide “typical months”, which resulted in 97 locations, with 30 locations dropped due to missing data. Read More

Historical Weather Files: The historical weather data is presented by year, starting with 2014 for 131 locations, of which 122 have data for all 8 years. Current year data is updated daily. Data for the current year uses modeled solar radiation data. The year prior to the current year also used modeled solar radiation data until the satellite-derived radiation data for the year prior to the current year becomes available. The weather data for the year prior to the current year is updated, using the satellite-derived radiation data, in approximately July of the current year. Read More

Sources: Weather station data are from the Integrated Surface Database and the National Solar Radiation Database. The Integrated Surface Database is maintained by the National Center for Environmental Information (NCEI). Satellite-derived solar radiation data originates from the National Solar Radiation Database (NSRDB) maintained by the National Renewable Energy Laboratory. For detailed information, including file naming conventions, formats, and data processing procedures, refer to: Update of California Weather Files for Use in Utility Energy Efficiency Programs and Building Energy Standard Compliance Calculations, CALMAC Study ID PGE0450.00. This study is available for download on the CALMAC Searchable Database, found elsewhere on this site. Read More

CAUTION: For current year weather files, there is usually a time lag of 2 to 10 days before the raw weather data becomes available. Be aware that the weather files are always presented as complete years so that they can be used in building simulation programs such as eQUEST. Data points beyond the retrieval date are filled with repeated values from the latest available data and identified with an "R" (Repeated) flag in the FIN4 format files. These values should never be used in any calculations. Users are advised to read the User Guide.

Click here for User Guide describing the CALMAC weather files in more detail