As Boulder braces for a hotter, drier future, new climate models tailored specifically to the city are providing a clearer picture of the risks ahead. By 2030, Boulder could see almost 30 days above 95 degrees, 200 high fire-risk days and several extreme precipitation events annually 鈥� a dramatic shift from historical norms.
The city commissioned these projections as part of its expanding climate resilience efforts, aiming to equip residents, businesses and policymakers with data to guide adaptation and mitigation strategies.
The models were developed by Resilience Analytics using observational data from the University of Colorado. They refine global climate projections to a hyperlocal scale, accounting for Boulder鈥檚 unique topography and climate patterns.
鈥淕rid cells in global climate models can be up to 100 miles wide, so they aren鈥檛 really sufficient for analyzing local impacts,鈥� said Kate Galbo, a sustainability data analyst for the city. Boulder is among the first communities of its size to develop downscaled climate models tailored specifically to its geography.
The city focused on heat, extreme precipitation, drought and fire risk 鈥� the most pressing climate threats for Boulder.
Boulder has already seen dramatic changes. Historic data, averaged from 1986 to 2005, provided the city a baseline for comparison, said Brett KenCairn, the city鈥檚 senior policy adviser for climate and resilience. He said his wife, who was born in Boulder, has witnessed the shift firsthand.
鈥淚n the course of a generation, she鈥檚 gone from seeing temperate afternoon thunderstorms 鈥� and you never needed air conditioning 鈥� to the very different circumstances we live in now.鈥�
The climate shift: Then, now and what鈥檚 next
To understand how much Boulder鈥檚 climate has changed, researchers compared past and present conditions:
Historic Baseline (1986鈥�2005):
- 5 days per year over 95掳F
- 14 high fire-risk days per year
- 1 extreme precipitation event every 5 years
Recent Data (2018鈥�2022):
- 10 days per year over 95掳F
- 116 high fire-risk days per year
- 57 drought days per year
- 3-day heatwave maximum average: 98掳F
Projected by 2030:
- 28 or more days per year over 95掳F
- 192 high fire-risk days per year
- 2.5 extreme precipitation events every 5 years
- 151 or more drought days per year
- 3-day heatwave maximum average: 101掳F
Projected by 2050:
- 42 or more days per year over 95掳F
- 230 or more high fire-risk days 鈥� about two-thirds of the year
- 2.5 extreme precipitation events every 5 years
- 170 drought days per year
- Heatwaves reaching 103掳F
These findings confirm what many Boulder residents are already experiencing: longer, hotter summers and more frequent extreme weather events.
鈥淚f a person is thinking, 鈥榃e鈥檝e just had a few hot years, but it will go back to something else,鈥� that鈥檚 probably not going to be the case,鈥� KenCairn said.
Climate projections for Boulder show rising heat, increased fire risk and more frequent extreme precipitation. Image courtesy of City of Boulder
What can be done?
Boulder is looking for ways to blunt the worst of the heat and fire risks. Galbo said the city worked with a team from Georgia Tech to model different cooling methods.
鈥淲e see a pretty significant amount of cooling by increasing tree canopy, as well as a pretty stark increase in temperature from losing tree canopy,鈥� Galbo said.
is already working to maintain the city鈥檚 trees and gather local heat data. But KenCairn warns that simply planting more drought-resistant trees from warmer climates won鈥檛 be enough, since Boulder still experiences extreme cold snaps that these trees wouldn鈥檛 tolerate.
Beyond tree cover, other possible climate adaptations include burying power lines to reduce wildfire risk, expanding HVAC systems in schools and other buildings that historically didn鈥檛 need them, and investing in distributed energy storage for a more reliable power grid.
Mapleton Mobile Home Park has been planting trees and creating shaded outdoor areas to prepare for extreme heat. Credit: Por Jaijongkit The city also hopes to map out the most vulnerable populations, including low-income residents, seniors and people living near canyon mouths 鈥� areas prone to extreme climate impacts.
鈥淭hat鈥檚 going to be a really important part of helping us,鈥� KenCairn said, 鈥渂ecause we can鈥檛 act everywhere at full scale.鈥�
KenCairn sees the climate models as a tool to engage the community and highlight risks, especially in higher-risk areas.
鈥淲e need to ground that truth with our community itself,鈥� he said. The latest data will be publicly accessible through a Climate Action Plan the city plans to release this spring.
He hopes this leads to stronger tree protection ordinances and landscaping codes designed to enhance hydration and cooling.
Boulder City Councilmembers are working to amend the city鈥檚 zoning and building codes . This could include prohibiting highly flammable plants and trees, such as junipers, in new landscaping projects. They also want the city to require water-efficient landscaping with drought-tolerant plants while strengthening tree protection ordinances and landscaping codes.
KenCairn also encourages residents to assess their own homes and landscapes for ways to improve resilience. This could include learning about heat pumps or installing pollinator habitats that use less water and provide cooling.
He said climate experts no longer understand nature as just something visually appealing or a place for recreation. 鈥淚t鈥檚 literally providing critical life support services.鈥�
While the new models provide a roadmap, climate projections are not guarantees. Climate change can progress in nonlinear ways, KenCairn explained.
鈥淵ou reach certain thresholds, or tipping points, after which a whole series of other things happen,鈥� he said. 鈥淵ou get things warm enough, and suddenly a whole ice sheet slides off, and then that changes the whole dynamic.鈥�
Losing an entire ice sheet, for example, could disrupt a critical Atlantic Ocean current that helps maintain Northern Europe鈥檚 temperate climate, potentially triggering widespread changes.
To ensure accuracy, scientists test models against historical data. While the future will never perfectly match projections, strong models increase confidence in general trends.
KenCairn expects the city to update its climate models in the next two to three years as technology advances and more data becomes available.
Por Jaijongkit is a reporter for the Boulder Reporting Lab. Her work frequently appears on-air at KUNC 91.5 FM and online at KUNC.org. Contact Por at Por.Jaijongkit@boulderreportinglab.org.