Aptly enough, it was 60 degrees in Michigan, in December, the day that 195 nations agreed to take steps to reduce carbon emissions.
Carbon dioxide from those emissions is heating the atmosphere, melting glaciers, and increasing sea levels.
In Ann Arbor, several hundred people joined a "Michigan Climate March," not to protest the accord, really, but to demand that governments go further.
At a rally following the march through city streets, participants held aloft signs bearing messages like, "I Love Clean Air," and "This is a Crisis."
A huge papier-mâché puppet with a globe for a head symbolizing Mother Earth looked down on the crowd, while people sang along to Woodie Guthrie's "This Land is Your Land."
Speakers included Michigan Congresswoman Debbie Dingell and Washtenaw County Commissioner Yousef Rabhi.
Rabhi told the crowd that humanity is running out of time to try to prevent the worst potential effects of climate change.
"We have the technology to do that," he said. "What we don't have is the political will to make that happen."
People were urged to contact politicians, including Michigan Gov. Rick Snyder, to demand that more be done to fight climate change.
Climate researchers believe the emissions cuts agreed to at Paris are only half of what is needed to avert a climate disaster.