Spring is a transitional season. It is a time when the chill of winter fades away and the warmth of summer gradually returns. But, as our climate changes, the season is heating up.

Across the contiguous United States, spring temperatures have increased an average of more than 2°F over the past fifty years, according to Climate Central. The southwest part of the country has seen the fastest seasonal increase, with Las Vegas, NV and Tucson, AZ warming more than 6°F since 1970.

Warming temperatures mean more frost-free days. While this may lengthen the growing season for some crops, it also extends the allergy season and allows pests like mosquitos and ticks to live and thrive longer.

Looking ahead, if greenhouse gas emissions continue to rise, scientists say spring could arrive at least two weeks earlier by 2050 compared to recent years.