Visitors to Snowdonia are being urged to take extra care during the half-term holidays.
The warning comes after the clocks went back at the end of British Summer Time, meaning fewer daylight hours.
Key safety points have been issued for those venturing up the mountain for the end of October and start of November.
Phil Benbow, chairman of the MountainSafe Partnership, said: "There is a significant increase in calls to rescue teams when the clocks go back."
- Prepare well. Have the right equipment - map, compass, torch, food, drink, whistle, first aid kit and fully charged mobile phone
- Latest weather and ground information. Check the Met Office Mountain Weather forecast and be prepared to turn back if weather worsens
- Dress appropriately - strong walking boots, several layers of clothing (including warm ones), gloves, hat, waterproof jacket and trousers
- Plan your route before setting off and ask for local advice.
- Know your limits. Be aware of your own and your group's fitness levels.
Mr Benbow added: "At this time of year it is important to carry a working torch, even if you plan to get back before dark, and don't rely on your mobile phone and the rescue team to get you out of trouble."