Arizona will get a lot hotter in the next 20 years. Here's what your county could see

Within two decades, counties across Arizona are expected to see a significant increase in temperatures, potentially exposing residents to more harmful effects of warming, according to a USA TODAY analysis of climate projection data .

Compared with historical data, Arizona's average annual temperatures could see an increase of three degrees in the next 20 years, according to data from the Climate Impact Lab . The analysis uses county-level temperature projections to assess how annual warming and extreme heat are expected to change from 2020 to 2040.

The state will also see a 20% increase in days above 95 degrees and a two-degree increase in average summer temperatures.

“We’re already experiencing an increase in warming and extreme heat across the country,” said Kelly McCusker, a climate scientist at the Climate Impact Lab. “I think a lot about how that will worsen ... and how that heat affects people unequally.”

How much hotter will your Arizona county get?

Here's what you could expect in your county by 2040:

• Maricopa : Maricopa County is expected to see a moderate increase in temperature of about 2.42 degrees, and it may have roughly 17 more days above 90 degrees every year.
• Pima : Pima County is expected to see a moderate increase in temperature of about 2.38 degrees, and it may have roughly 22 more days above 90 degrees every year.
• Pinal : Pinal County is expected to see a moderate increase in temperature of about 2.39 degrees, and it may have roughly 17 more days above 90 degrees every year.
• Apache : Apache County is expected to see a moderate increase in temperature of about 2.54 degrees, and it may have roughly 14 more days above 90 degrees every year.
• Cochise: Cochise County is expected to see a moderate increase in temperature of about 2.38 degrees, and it may have roughly 24 more days above 90 degrees every year.
• Coconino: Coconino County is expected to see a moderate increase in temperature of about 2.48 degrees, and it may have roughly 12 more days above 90 degrees every year.
• Gila : Gila County is expected to see a moderate increase in temperature of about 2.38 degrees, and it may have roughly 21 more days above 90 degrees every year.
• Graham : Graham County is expected to see a moderate increase in temperature of about 2.38 degrees, and it may have roughly 24 more days above 90 degrees every year.
• Greenlee : Greenlee County is expected to see a moderate increase in temperature of about 2.42 degrees, and it may have roughly 23 more days above 90 degrees every year.
• La Paz : La Paz County is expected to see a moderate increase in temperature of about 2.28 degrees, and it may have roughly 15 more days above 90 degrees every year.
• Mohave : Mohave County is expected to see a moderate increase in temperature of about 2.33 degrees, and it may have roughly 15 more days above 90 degrees every year.
• Navajo : Navajo County is expected to see a moderate increase in temperature of about 2.4 degrees, and it may have roughly 16 more days above 90 degrees every year.
• Santa Cruz : Santa Cruz County is expected to see a moderate increase in temperature of about 2.31 degrees, and it may have roughly 24 more days above 90 degrees every year.
• Yavapai : Yavapai County is expected to see a moderate increase in temperature of about 2.37 degrees, and it may have roughly 22 more days above 90 degrees every year.
• Yuma : Yuma County is expected to see a moderate increase in temperature of about 2.26 degrees, and it may have roughly 16 more days above 90 degrees every year.

More: Yes, it gets hot in metro Phoenix. But here's when the weather cools down

How will warming impact the rest of the US?

Climate change is expected to have a striking but uneven impact on temperatures across the U.S. in the next two decades, according to USA TODAY.

The Gulf Coast could experience a significant increase in extreme heat. Large parts of the northern U.S. could see dramatic warming. And across the country, more Americans may be exposed to the harmful effects of heating.

The analysis also highlights the potential for cooler regions of the U.S. to experience a significant increase in average annual temperatures. Meanwhile, hotter states like Arizona are expected to see the biggest increase in days above 95 degrees.

Across the country, escaping the effects of climate change may become more challenging. While historically cooler regions are getting much warmer, hotter regions face more dangerous heat.

Dangerous heat on the rise in warmer regions

Many counties that already experience warm weather will face many more days of dangerous heat within two decades, according to projections.

In Arizona, Yavapai, Gila, Pima, Graham, Greenlee, Santa Cruz and Cochise were among U.S. counties expected to see the most additional days above 90 degrees by 2040.

USA TODAY grouped counties based on the number of additional days above 90 degrees they may experience.

• More than 1,000 counties are projected to see the biggest increase with more than 21 additional days above 90 degrees.
• Nearly 750 counties with 14 to 21 additional days above 90 degrees may experience “more” increase in extreme heat, while about 640 counties with seven to 14 additional days are expected to see “some.”
• Roughly 830 counties are projected to see “few” additional days of extreme heat, meaning fewer than seven more days above 90 degrees.

These categories also closely approximate natural “breaks” in the distribution of data, and the groupings show regions that could face a notable increase in extreme heat risk.

Exposure to extreme heat can be uncomfortable at best, making it difficult to focus when learning or working. At worst, it can be deadly. Heat is already the leading cause of climate-related deaths in the U.S., and more days above 90 degrees may increase the number of heat-related deaths and illnesses.

When air temperature exceeds 90 degrees, the human body gains more heat than it can release. Sweating can allow the body to cool further. But, in hot and humid climates, sweat may not evaporate fast enough, which can cause the body’s internal temperature to rise dangerously.

Children and older adults are most at risk of developing heat-related health complications, especially when they have preexisting conditions.

Although extreme heat poses the biggest threat in places not prepared for hot weather, people accustomed to warmer climates can still be overwhelmed by extreme heat episodes.

Adding more green spaces to urban areas, installing more air conditioning and constructing cooling centers can help people avoid the worst effects of heat, but not all communities have the funding to implement these solutions.

McCusker said although people may be able to adjust to a rapidly warming country, an effective strategy to reduce the worst impacts of warming is to reduce emissions.

“We’ve shown that lives can be saved,” McCusker said.

What to know about the projections

USA TODAY used data from climate models that make two main assumptions. First, future population and economic development follow historical patterns. Second, stringent climate policies enable significant emissions reductions by 2100.

Scientists refer to this set of assumptions as a “middle of the road” scenario for how social and economic changes may impact how climate change unfolds.

Technically, the scenario is named SSP2-4.5 and is just one of many possible climate scenarios.

USA TODAY grouped counties with similar increases in warming into three categories.

• Roughly 1,100 counties are projected to see a “significant” increase of 2.6 to 4.5 degrees in average annual temperatures.
• More than 1,600 counties with an increase of 2.1 to 2.6 degrees may see “moderate” warming.
• Just 517 counties are likely to experience “minimal” warming: an increase of 1.0 to 2.1 degrees in annual temperatures.

These boundaries were chosen because they represent natural “breaks” in the distribution of data.

This article originally appeared on Arizona Republic: Arizona will get a lot hotter in the next 20 years. Here's what your county could see