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Arizona: Risks & Trends

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Same standard as every other page on this site: every figure below is independently sourced, and figures that vary across sources, or measure genuinely different things, are flagged as such rather than collapsed into one number that looks more precise than the underlying data actually supports.

Maricopa County heat deaths: a tracked, worsening annual toll

MetricFigure
2023 heat-related deaths 645 (record high, 52% above the prior record)
2024 heat-related deaths 602 (first year-over-year decline in a decade, despite the hottest summer on record)
Longest daily-death streak (2024) 44 consecutive days (June 18-July 31) with at least one heat death every day
Deaths during that streak 355
Share of 2023 deaths aged 50+ ~2 in 3
Share of 2023 deaths that were men ~3 in 4
Share of 2024 deaths that occurred outdoors 77%

Why 2024's decline doesn't mean the risk eased

2024 was Phoenix’s hottest summer on record, yet heat deaths fell for the first time in a decade, most likely reflecting expanded heat-relief efforts (cooling centers, outreach) rather than milder conditions. Both facts are true at once: the underlying heat exposure kept getting worse, and the death toll dropped anyway, a genuine public-health success story layered on top of a still-worsening climate trend.

The Colorado River shortage: Arizona’s deepest cuts of any state on the river

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Current shortage tier Tier 1 (in effect 2022, 2024, 2025, 2026)
Arizona's annual Tier 1 reduction 512,000 acre-feet
Share of Central Arizona Project's normal supply ~30%
Share of Arizona's total Colorado River supply ~18%
Share of Arizona's total water supply (all sources) Just under 8%
Additional Lower Basin cuts starting 2027 1.25 million acre-feet
Current operating guidelines expire End of 2026

Arizona’s Central Arizona Project water right sits junior to other states’ Colorado River allocations under the interstate agreements governing the river, which is why Arizona absorbs the largest share of cuts under the tiered shortage system even though its total allocation is smaller than California’s. The 2007 interim operating guidelines that have governed cuts since then expire at the end of 2026, and negotiations over what replaces them will directly determine how much deeper Arizona’s cuts go after that.

What these two have in common

Both of Arizona’s defining risks get worse the longer the underlying trend continues, and neither has a single fixed end date. Extreme heat and water scarcity reinforce each other in a practical sense too: less water available for landscaping and cooling infrastructure makes heat exposure harder to manage, which is part of why this manual treats water storage, heat safety, and general Tier 1-2 self-sufficiency as connected priorities rather than separate concerns here specifically.

Sources