The Mountaineering Council of Scotland (MCofS) said yesterday that this month had produced torrential rain and gales, making “classic conditions for hypothermia” amongst those who are unprepared.
They warned walkers tackling the peaks are most at risk and advised them to take the necessary precautions.
The Met Office have also described the weather in the region as “unseasonably chilly”.
Forecasters said the typical August average temperatures across Inverness, Perth and Aberdeenshire for this time of year are normally between 8-9C in the early morning rising to between 16-17C maximum later in the day.
But this can drop to and 4C at peaks above 900 metres and 0C at the summits.
There are also strong winds with gusts of up to 50 mph forecast for the Munros as showers pass through.
The MCofS, the representative organisation for climbers and hill-walkers, said the warning was prompted by flooding, gale force winds and a forecast of sleet on Scotland’s highest mountains.
David Monteith, Mountain Safety Adviser with the 12,000 member-organisation, said: “It may still be August but hypothermia is a real risk if people are not properly prepared.
“Sleet has been forecast for the higher hills in the coming week, and we’ve just seen torrential rain which swept away two bridges in the Cairngorms and made many streams impassable for a period, as well as causing landslips and damage to footpaths.
“Wind and rain are the classic combination for bringing on hypothermia. Once someone’s clothes are wet through the wind can have a tremendous chilling effect, even though the air temperature is not that low in itself.”
Hypothermia occurs when a person’s body temperature drops below 35°C, normal body temperature being around 37°C.
Hypothermia can quickly become life threatening and should be treated as a medical emergency.
The symptoms of mild hypothermia include – confusion, loss of judgement and reasoning, which can lead to someone with hypothermia deciding to remove clothing despite being very cold, along with loss of co-ordination, slurred speech and drowsiness.
More severe symptoms include a body temperature below 28C leading to unconsciousness, shallow or no breathing, a weak, irregular pulse or no pulse and dilated pupils.
Someone with severe hypothermia may appear to be dead when in fact they are just seriously ill, health experts say.
Medical treatment can still be used to resuscitate people with severe hypothermia, although it is often fatal.
Mr Monteith said anyone planning a day in the mountains should make sure they check mountain-specific weather forecasts such as MWIS and the Met Office, and carefully plan routes and provisions.
He added: “Walkers should also consider a simpler, low level route option or plan a viable escape route if they are aiming to go high. The provision of a bivouac bag, group shelter and some modern lightweight insulating clothing can be a lifesaver if things do go wrong. Add to this some first aid knowledge and the ability to convey an emergency message and preparations are in good order.
“The medium-term weather forecast is for some respite in the wet and cold weather but this will only be temporary. The nights are now drawing in and next month sees the autumnal equinox, after which the number of daylight hours shrinks noticeably.”
According to the General Register Office for Scotland there have been on average 78 deaths per year involving hypothermia from 2000 to 2013.