Lake District rescuers have warned that people are relying "totally on smartphone technology" on the fells.
Rescue teams have attended 606 callouts in 2022 up until Boxing Day morning.
Richard Warren, from the Lake District Search and Mountain Rescue Association, said phone batteries drain "very, very quickly" when it's cold.
On Christmas Day Langdale and Ambleside volunteers were called to Buckstones Jump, near Rydal, after a walker became unwell and later died.
The rescue was said to have been "challenging" due to weather conditions, and involved the Coastguard helicopter after the North West Air Ambulance had to abort its operation.
There are some 400 mountain rescue volunteers across the Lake District.
"It's nearly as busy as our busiest year which was 2021 with 681 callouts," Mr Warren told BBC Radio Cumbria.
"I would expect that by the end of the year we will be on around 620, it's been a very busy year.
"We had a very busy January last year so we just keep our fingers crossed people are listening to the safety messages."
Mr Warren, stressed the importance of carrying a compass and map, which he called "critical" and urged people to be "adventure smart" and check safety advice online before setting off on a walk.
He also warned people to be aware of the dangers of cold water, after an increase in the popularity of paddle-boarding across the area.
"I drove past Grasmere the other day, there was a person out [with] no buoyancy aid. It didn't look like they had a tether, and if you fall into the water you may not survive.
"We are trying to avoid these tragic situations."
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