FILE - Swimmers enjoy the Willamette River in downtown Portland in 2018.
Willie Levenson
Many people are heading to beaches, rivers and lakes for a cool splash or other water activities as weather across Oregon gets hotter this week, but the National Weather Service warns of hidden dangers when swimming.
In Portland, for instance, temperatures could reach as high as 76 degrees on Sunday and throughout the coming week. But the federal agency says the water can remain very cold even when the air is warm. Plunging into cold water at any temperature can be dangerous if you are not prepared for the sudden effects it can have on your body and brain.
The weather is getting warm this weekend & while it may be tempting to hit local rivers to cool down, the water is VERY cold.
— NWS Portland (@NWSPortland) April 3, 2026
Be sure to follow the Northwest River Forecast Center https://t.co/bEpeSStcpJ all of your water and hydro forecast needs! pic.twitter.com/ok4moKveYm
When your body hits cold water, cold shock or hypothermia can cause dramatic changes in breathing, heart rate and blood pressure, the NWS warns. The agency adds that the sudden gasp and rapid breathing alone increase the risk of drowning, even for confident swimmers in calm water.
Jason Tyrus, a deputy with the Multnomah County River Patrol, told OPB last April that anyone operating a boat should carry enough life jackets for everyone on board. He also recommends researching a body of water before visiting.
The Metro regional government distributes life jackets at all of its parks. Spokesperson Hanna Erickson told OPB last April that properly worn life jackets can help if someone falls off a boat or encounters hazards in the water, as rivers can have sudden drops and submerged branches that can snag limbs.
