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 is a set of 86 "typical year" weather files developed from the 12 years of historical record 1998 through 2009 that was mandated by the California Energy Commission for use in Title 24 compliance calculations from 2010 through 2022.  As required by the California Energy Commission, the CZ2010 use the same "typical months" for all 86 locations.
• CZ2022 is a set of 97 "typical year" weather files developed from the 20 years of historical record 1998 through 2017 that was mandated by the California Energy Commission for  use in compliance calculation for Title 24 Version 2022. Like the CZ2010, CZ2022 uses the same "typical months" for all 97 locations.  Due to this constraint, 30 locations with historical data were dropped from the set.
• CALEE2018 is a set of 127 "typical year" weather files developed from the 12 years of historical record 2006 through 2017. (1) the CALEE2018 (formerly called the CZ2018) uses location-specific  "typical months", the designation "2018" refers to the year of creation, rather than the Title 24 version; in other words, the CALEE2018 is contemporary with the CZ2022 although it uses the last 12 years rather than the last 20 years.
• CALEE2024 is a set of "typical year" weather files developed from the 12 years of  historical record  2012 to 2023.  (1) as with the CALEE2018, the CALEE2024 uses location-specific "typical months", (2) the designation "2024" refers to the year of creation, rather than the Title-24 version; in other words, the CALEE2024 files actually use more current  weather data than do the CZ2025.

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