Cities with most severe heat island effects

How much heat islands could increase a city's temperature relative to its outer surroundings
City Potential heat increase Critical factors
New Orleans 8.94F Albedo, impermeable surface
Newark, NJ 7.71F Impermeable surface, building height, population density
New York City 7.62F Building height, impermeable surface, population density
Houston 7.46F Impermeable surface, albedo
San Francisco 7.37F Building height, impermeable surface, population density
Boston 7.24F Building height, population density
Chicago 7.24F Building height, impermeable surface, population density
Miami 7.24F Building height, Impermeable surface
Baltimore, Maryland 7.08F Building height, impermeable surface
Providence, RI 7.08F Building height, impermeable surface
Sacramento, Calif. 7.08F Building height, Impermeable surface
Salinas, Calif. 7.08F Albedo, impermeable surface
Burlington, Vermont 7.05F Albedo
Bend, Oregon 6.97F Albedo, impermeable surface
Cleveland, Ohio 6.97F Building height, impermeable surface
Detroit 6.97F Impermeable surface, building height
Erie, Pa. 6.97F Impermeable surface
Fresno, Calif. 6.97F Impermeable surface
Lafayette, La. 6.97F Impermeable surface, building height
McAllen, Texas 6.97F Impermeable surface

Guardian graphic. Source: Climate Central