Boston has 15 more mosquito days than it did in 1980

The number of "mosquito days" — that is, those with the hot and humid weather the flying insects crave — has trended up in Boston over the past several decades, per a new analysis.

By the numbers: Boston now has an average of over 15 more mosquito days per year since 1980.

• The report, from nonprofit climate science research organization Climate Central, defines a "mosquito day" as one with average relative humidity of 42% or higher, plus daily temperatures of 50° – 95° F.

Why it matters: Mosquitoes are more than just a nuisance — they're a public health threat, carrying diseases such as malaria, West Nile, Zika and more.

The big picture: 71% of the 242 locations Climate Central analyzed saw an increase of about 16 mosquito days on average between 1979 and 2022.