Citizen Science Heat Mapping Study Shows Hots Spots Across County

Stay Cool Missoula, a collaborative partnership among Missoula County, the City of Missoula and Climate Smart Missoula, recently released heat index and temperature maps that resulted from Heat Watch, a countywide heat mapping project conducted last summer.

 

The aim of Heat Watch – the first of its kind in Montana – is to understand heat distribution across Missoula County and help communities plan and prepare for rising temperatures. Among other findings, the mapping campaign confirmed temperature variability throughout the day and revealed hot spots, or urban heat islands, that exist in the county.

 

For example, the Westside neighborhood of Missoula, characterized by large industrial and commercial areas with impervious surfaces, exemplified a heat island. This area stayed hot throughout the day and radiated heat to warm surrounding residential neighborhoods. The Bonner and Milltown areas east of Missoula, though they’re farther from the urban core, remained warm and developed hot spots throughout the day. For comparison, the University District, which boasts a dense, mature tree canopy and lacks surrounding industrial or commercial landscapes, remained cooler than other neighborhoods throughout the day.

 

The Heat Watch campaign was held Aug. 12, 2025, and was coordinated by the Stay Cool Missoula team and partners from the Center for Collaborative Heat Monitoring, CAPA Strategies, and the Oregon Museum of Science and Industry. More than 30 citizen science volunteers collected the data on a hot, clear day. Using simple heat sensors mounted to vehicles, volunteers drove assigned routes three times during the day (6-7 a.m., 3-4 p.m. and 7-8 p.m.), recording nearly 76,000 air temperature and humidity measurements across 93 square miles across the county.

 

Extreme heat is one of the top five extreme weather hazards in Missoula County. The number of annual days above 90 degrees is increasing in the county, a trend which is expected to continue as a result of climate change. Heat is the number one weather-related killer nationwide and a growing threat in Montana. These deaths are preventable with proper planning and action.

 

The results of Heat Watch indicate residents living, working and recreating in different parts of the county may have different exposures to high temperatures and hot spots. While some areas may have safe temperatures for outdoor activities, other areas may put people at risk for heat-related illnesses, especially during the warmest afternoon hours. Knowing which areas are subjected to higher temperatures can help communities target heat mitigation efforts and help residents prepare for and respond to extreme heat.

 

The full results from Heat Watch are available in the summary report and in an interactive heat map that allows users to view morning, afternoon and evening air temperature and heat index data throughout the county. The publicly available dataset can be downloaded  here alongside the report and interactive map.

 

The Stay Cool Missoula team hopes to use this data to inform heat-related policies like our Extreme Heat Toolkit; the overarching community climate resilience plan Climate Ready Missoula; and other plans created by local government and community partners at other agencies.

 

Heat Watch is just one part of Stay Cool Missoula’s larger local effort to prepare for and respond to extreme heat in Missoula County. Prior to the heat mapping effort, the team released Stay Cool Missoula Story Map, a guide that connects people with resources for extreme heat. Area residents and visitors are encouraged to visit this site to learn more about heat in Missoula County and how to stay safe during heat waves.

The Stay Cool Missoula team will continue to use the Heat Watch results to move forward on heat policy and action. Community members can stay informed online at https://www.climatereadymissoula.org/staycool.html.