It's not even the summer: Miami just set a heat record for May

Miami residents are used to heat and humidity, but last month was insufferable, with day after day of record-challenging, sultry heat.

Why it matters: The extreme heat, tied to unusually warm ocean waters and a massive heat dome over Mexico and Central America , poses a variety of health risks .

The big picture: Brian McNoldy, an atmospheric science researcher at the University of Miami, told Axios that Miami's temperatures last month were "brutal."

• It was Miami's warmest May on record, with a new monthly record high for the heat index and records for daily dew points and high temperatures, he told Axios via email.
• The city had two straight days with a heat index of 112°F, the city's third-highest heat index on record.
• The rest of Florida did not fare much better, with monthly high temperature records set again last week.

What they're saying: The "normal part of extreme heat season" was pushed into May this year, he said.

• "It's pretty rough. July, August and September here are very thick. So I think extending that season [into May] is not the most welcome thing."

Between the lines: Human-caused climate change is driving much of the trend toward more frequent, longer-lasting and more intense heat waves.

For example, Climate Central's Climate Shift Index shows that climate change made reaching daily average temperatures on May 28 at least five times more likely in South Florida.