Halloween weather can be highly variable depending on the year.
Later frosts mean longer growing seasons for the U.S.
This is how much the average frost-free season has changed since 1970.
The decrease in cool nights is one feature of an overall fall warming trend.
Climate change is altering important elements affecting fall foliage.
The annual Arctic sea ice minimum extent has been below average every year since 2002.
Climate change has delayed the date of the annual Arctic sea ice minimum.
Here's how hot this summer has been compared to the hottest and coolest summers on record in your city.