The CHC Heat Monitor products are a tool to track and provide early warning of extreme heat. The observed data maps provide low-latency time estimates of extreme temperature using the high resolution CHIRTS-ERA5 maximum temperature and heat index. The forecast data maps show an outlook for the next 15 days, using NCEP GEFS forecasts that are post-processed using CHIRTS-ERA5 Tmax and CHIRPS precipitation data.

 

The Observed Heat Monitor products, updated six times a month, use the high-resolution CHIRTS-ERA5 maximum temperature and heat index datasets to compare recent conditions with the historical record over 1-, 3-, and 6-pentad (~5 day to 1 month) periods. 

 

The CHIRTS-ERA5 dataset combines satellite and station-based estimates of the Climate Hazards Center Infrared Temperature with Stations (CHIRTS) historical product (1983–2016) with the regularly updated (5-day latency) ECMWF ERA5 (T) reanalysis dataset. The resulting dataset provides a downscaled and bias-corrected ERA5 temperature product made compatible with the CHIRTS dataset. More information about CHIRTS-ERA5 can be found here: https://www.chc.ucsb.edu/data/chirts-era5. 

 

The Forecast Heat Monitor products, updated daily, combine bias-corrected and enhanced resolution versions of NCEP GEFS temperature and rainfall forecasts (CHIRTS-GEFS and CHIRPS-GEFS) to highlight locations where unusually high maximum temperatures coincide with below-average rainfall conditions during the next 15 days. More information about the observed and forecast heat products are given below.

 

The Observed Agri Heat maps highlight unusually high maximum temperatures across active croplands during the selected 1-, 3-, or 6-pentad period. Colored areas indicate locations where the average maximum temperature exceeded the historical 80th percentile and where one or more major crops (maize, wheat, rice, millet, sorghum, or soybeans) are in an active stage of the growing season, from planting through reproductive development. Within these areas, the yellow-to-red color scale indicates the magnitude of the temperature conditions. Gray areas represent croplands that are not currently within the selected active crop-growth window. The product tracks typical stages of crop development using the GEOGLAM Crop Monitor bi-monthly crop calendars, and applies global cropland masks from the European Commission JRC Anomaly Hotspots of Agricultural Production (ASAP) and FEWS NET. Archived Agri Heat maps are available here.

 

The Observed Global Hotspots maps show regions where maximum temperatures exceeded the 80th percentile during the most recent 1-, 3-, and 6-pentads. The maps can be used to identify the location, extent, and persistence of unusually high temperatures, highlighting areas where prolonged heat may increase the potential for impacts on human health, ecosystems, agriculture, water resources, and infrastructure. Archived Global Hotspot maps are available here.

 

The Observed Global Heat Health product highlights areas where the average Heat Index exceeded the 80th percentile during the selected 1-, 3-, or 6-pentad monitoring period. The Heat Index, also known as the apparent temperature, combines air temperature and relative humidity to estimate how hot conditions feel to the human body. Elevated humidity reduces the body's ability to cool itself through sweating, increasing the risk of heat-related illness.

 

The color scale represents the heat severity. 

Yellow (80–90°F): Caution

Orange (90–103°F): Extreme Caution

Red (103–124°F): Danger

Dark Red (>125°F): Extreme Danger

 

Archived observed Global Heat Health maps are available here.

 

 

The CHC Heat Monitor Forecast products support early warning of extreme heat by highlighting areas where unusually high maximum temperatures coincide with below-average rainfall, conditions that can increase heat and moisture stress. The Global Heat maps highlight these locations, showing the average maximum temperature for the period, only where temperatures are forecast to be higher than usual and hot (greater than 30 °C). The Agri Heat maps focus on active croplands where maize, wheat, rice, millet, sorghum, or soybeans are typically between the planting and reproductive stages. In ‘Extreme Tmax’ forecast maps, yellow to dark red colors highlight locations where forecast maximum temperatures exceed the 80th percentile. The ‘Above Average’ Tmax maps more extensively show temperatures using a less strict criteria of Tmax exceeding the 50th percentile. Stippling indicates locations where below-average rainfall is forecast. 

 

Current and past forecast ‘Hot and Dry’ maps are available here.

 

The Forecast Heat Monitor products combine the CHIRTS-GEFS temperature and CHIRPS-GEFS rainfall forecasts, and are produced daily for an outlook showing the forecast average conditions during the next 15 days. The CHIRTS-GEFS is a bias-corrected and downscaled version of NCEP Global Ensemble Forecast System (GEFS) version 12 temperature forecasts. The GEFS data is adjusted to match the recent (2000–2019) historical distribution and high 0.05 degree spatial resolution of the CHIRTS-ERA5 temperature data. For each forecast date and lead time, the GEFS climatological temperature is subtracted from the GEFS forecast to calculate a temperature anomaly. This anomaly is then added to the corresponding CHIRTS-ERA5 climatology to produce the CHIRTS-GEFS temperature forecasts. CHIRTS-GEFS forecasts can be accessed through the Early Warning Explorer (EWX) as well as the data archive here. 

To support early warning, the CHC processes and shares climate variable forecasts from subseasonal-to-seasonal dynamical forecast systems. Impact-oriented forecast maps on the Heat Monitor page integrate fine resolution and bias-corrected next 15-day forecast data, plus additional information to highlight the agricultural context and forecast extremity. For current multi-week outlooks that also relay the level of agreement across subseasonal forecast systems, check out the CHC Subseasonal Multi-Model Ensemble forecasts page for forecasts from SubC and ECMWF. There you can find forecasts of daily minimum, maximum, and mean temperatures and rainfall, for upcoming weeks and 15- and 30-day periods. Interested in outlooks for the next six to eight months? Check out the seasonal 3-month temperature and rainfall forecasts, updated around the 6th day of each month, on the CHC Seasonal Multi-Model Ensemble forecasts page.