Why Minnesota Burns: Melanoma Risk Beyond Latitude
- Ryan M. Trowbridge, MD, MS, MA
- Mar 23
- 3 min read
It’s easy to assume that sunnier states have higher skin cancer rates. After all, more sun means more ultraviolet (UV) radiation—so logically, more risk. But the data tell a more complicated story.
Minnesota, for example, receives significantly less UV radiation than Florida—about 50% less UVB and roughly 20% less UVA over the course of the year¹. Yet despite this, the melanoma incidence in Minnesota is nearly identical to that in Florida, at 19.5 and 19.0 cases per 100,000 people, respectively². If ambient UV exposure alone drove melanoma risk, we would expect much lower rates in the northern state. But clearly, that’s not the case.
A key factor may be behavior. In a national CDC survey of sunburn prevalence, Minnesotans reported more sunburns than Floridians—about 30% more³! That’s striking, considering the reduced opportunity for UV exposure. It also points to an important reality: intermittent, intense UV exposure—especially resulting in sunburn—is a major risk factor for melanoma (and basal cell carcinoma), and possibly a stronger one than total cumulative dose.
It's undeniable that UV radiation intensity varies greatly by latitude, with UVB showing particularly steep reductions in northern regions¹. This pattern explains why squamous cell carcinoma (SCC), which is closely linked to chronic UVB exposure, shows a strong latitude gradient². But melanoma behaves differently. While still UV-related, it’s more often associated with intermittent, intense exposure patterns—the kind that lead to sunburn¹. And in Minnesota, that seems to be exactly what's happening.
In cold-climate states, in may be that people rush to embrace the sun during short summers. Many have lighter skin and often spend extended periods outdoors when UV levels spike—all factors that contribute to higher rates of sunburn³. Despite less UV availability overall, the pattern of exposure may be more dangerous.
This disconnect between UV dose and melanoma incidence challenges assumptions that high-latitude states are inherently lower-risk for the public. Although all else being equal (activity and time spent in the sun), northern latitudes are likely lower risk, significant variations in behavior lead to rates of skin cancer that correlate much less with ambient UV exposure than is expected². And because BCC, SCC and melanoma have different exposure-risk profiles, prevention strategies need to address both cumulative and episodic UV exposure patterns¹,².
The good news is that if we understand risk factors and patterns of behavior we can likely modify our risk factors significantly. Latitude isn't destiny, but sunburns and excessive sun exposure could be. While UV intensity certainly matters, behavior—including sun-seeking, tanning habits, and sun protection practices—may be just as important in determining who develops melanoma and other skin cancers. When living in northern climates, you may be able to relax on sun protective measures during low ambient UV seasons. But, when the sun emerges from its winter hibernation, don't let your alacrity for summer cause you to forget the importance of sun protection.
Dr. Ryan M. Trowbridge, MD, MS, MA
Harvard-Trained, Board-Certified Dermatologist and DermMythBuster
P.S. Have you come across any new or conflicting research on this topic? Please share—I’d love to explore it further with you!
References
Grigalavicius M, Moan J, Dahlback A, Juzeniene A. Daily, seasonal, and latitudinal variations in solar ultraviolet A and B radiation in relation to vitamin D production and risk for skin cancer. Int J Dermatol. 2016;55(Suppl 1):e23–e28. doi:10.1111/ijd.13065.
Aggarwal P, Knabel P, Fleischer AB Jr. United States burden of melanoma and non-melanoma skin cancer from 1990 to 2019. J Am Acad Dermatol. 2021;85(2):388-395. doi:10.1016/j.jaad.2021.03.109.
Saraiya M, Balluz L, Wen XJ, Joseph DA. Sunburn prevalence among adults—United States, 1999, 2003, and 2004. MMWR Morb Mortal Wkly Rep. 2007;56(21):524-528.
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