This weekend saw the first local transmission of the Zika virus in the continental United States. As of today, 14 people in South Florida have contracted the disease from infected mosquitos. Officials anticipate additional cases of “homegrown Zika,” but they don’t expect the disease will become widespread.

Since being discovered in Uganda in 1947, Zika has remained rare. Last year, however, the disease erupted in Brazil and has since spread across South America and the Caribbean, infecting hundreds of thousands of people. More than 4,600 Puerto Ricans have contracted Zika from mosquitos.

Most people who are infected experience no symptoms. Roughly 20 percent develop a fever, rash, nausea, joint pain or other mild symptoms. Zika is most pernicious in expectant mothers. Fetuses infected with the disease may develop abnormally small heads, leading to mental disability and early death.

Zika can be transmitted through sex or by mosquitos. Mosquitos that transmit Zika, principally the yellow fever mosquito (Aedes aegypti), thrive in warm climates, leading some to speculate that global warming has fueled the spread of the illness.

A new project from Climate Central shows that rising temperatures and increased humidity have lengthened mosquito season. The number of days with the ideal conditions has risen most dramatically in the Midwest and on the East Coast. In Baltimore and Durham, North Carolina has been extended by mosquito seasons by almost 40 days in the last 35 years.

Source: Climate Central

Among major American cities, Miami boasts the longest mosquito season — 337 days. The city offers extremely favorable conditions to Asian Tiger Mosquito (Aedes albopictus), another carrier of the Zika virus.

Officials are encouraging people in mosquito-prone areas like South Florida to wear insect repellent and cover up. The Centers for Disease Control and Prevention has discouraged pregnant women from traveling to high-risk areas, including northern Miami and Puerto Rico.

Jeremy Deaton writes for Nexus Media, a syndicated newswire covering climate, energy, politics, art and culture. You can follow him at @deaton_jeremy.