WMO Normals Explorer
WMO Climatological Standard Normals 1991-2020
The WMO Normals Explorer provides an interactive interface to the official WMO Climatological Standard Normals for the most recent 30-year reference period: 1991-2020.
Climatological Normals form a benchmark against which current weather conditions are assessed. They are an indicator of the conditions likely to be experienced in a given location over a long period. In 2015, the WMO changed the definition of standard normals to refer to the most-recent 30-year period finishing in a year ending with 0, replacing the non-overlapping consecutive periods used previously, ensuring that climate averages reflect our rapidly changing climate.
This dataset aggregates reference climate data calculated by national meteorological services globally. It is the definitive baseline for standard climate variables, such as mean temperature and precipitation totals, providing a uniform baseline across national borders.
Need help? Check the User Guide for detailed instructions.
Use the interactive explorer
Start at country level, then drill into individual stations to inspect map context and exportable normal records.
About this Data
The variables presented represent long-term averages from 1 January 1991 to 31 December 2020. The collection of these standard normals is coordinated by the World Meteorological Organization (WMO) to ensure consistency and comparability of climate classifications and anomalies globally.
Through Climate Explorer, you gain streamlined access to this global network of standard averages, allowing you to:
- Assess Baseline Climate: View typical temperature bounds, precipitation regimes, and sunshine hours.
- Analyze Regional Patterns: Compare specific climate indicators visually across multiple stations.
- Export Reference Data: Download CSV tables of all required standard variables for your research.
How to use this tool
- Global Navigation: The map starts with a global view. Click on any point to select a station.
- Filter by Country / Parameter: Use the sidebar to zoom into a specific country or change the visualized parameter (e.g., “Mean Temperature”, “Precipitation”).
- Adjust Time Window: Change the period rendered on the map (Annual vs specific months).
- Visualize & Export: Switch to the Dashboard tab to view dynamic charts and export raw table data.
How to Interpret WMO Normals
WMO normals are reference values, not forecasts. They summarize what is typical at a station over the 1 January 1991 to 31 December 2020 climate baseline, helping you compare present-day conditions against a modern long-term average.
When reading the explorer, keep these interpretation rules in mind:
- Annual vs Monthly Values: Annual views summarize the full year, while monthly views isolate the typical conditions for a single month such as January or July.
- Temperature Normals: Mean, maximum, and minimum temperature normals describe the expected thermal range at a location. Large seasonal swings usually indicate a more continental climate, while smaller swings often reflect maritime influence.
- Precipitation Totals: Monthly or annual precipitation normals show the typical accumulation over the baseline period. Wet-season peaks and dry-season troughs help reveal regional rainfall regimes.
- Precipitation Days: This variable indicates how often measurable precipitation occurs, which is different from total amount. Two stations may receive similar totals but differ strongly in how frequently rain or snow falls.
- Pressure and Vapor Pressure: Mean sea level pressure helps characterize prevailing synoptic conditions, while vapor pressure provides a useful measure of typical atmospheric moisture.
- Sunshine Duration: Sunshine normals highlight the seasonal rhythm of cloudiness and solar exposure, which can vary sharply between coastal, mountainous, and arid regions.
What WMO Normals Can and Cannot Tell You
Normals are ideal for understanding the baseline climate of a station, comparing locations, and placing current weather anomalies into context. They are less suitable for analyzing extremes, individual events, or rapid recent shifts that happened after the 1991-2020 period ended. For those use cases, historical archives such as GHCNh Explorer, GHCNm, or country-specific explorers like DWD and Météo-France may be a better fit.
Need more help? View the full WMO Normals User Guide for detailed instructions.
Data source
- WMO Climatological Normals documentation: https://community.wmo.int/site/knowledge-hub/programmes-and-initiatives/climate-services/wmo-climatological-normals.
- Data aggregated via Member submissions to the WMO Climatological Standard Normals 1991-2020 collection.
Frequently Asked Questions
What are Climatological Standard Normals?
Climatological standard normals are averages of climatological data computed for consecutive periods of 30 years. The current standard reference period is 1 January 1991 to 31 December 2020. They serve as a benchmark to assess current weather against past typical conditions.
Why did the WMO update the calculation period?
To ensure statistics reflect the rapidly shifting baseline caused by climate change, the WMO mandated that normals now refer to the most-recent 30-year period finishing in a year ending with 0 (e.g., 1991-2020), rather than waiting for non-overlapping periods.
How can I download the raw WMO Normals data?
Once you select a station on the interactive map, use the Dashboard tab. There, you can click Export CSV to download all the available parameters compiled for that station.