As global warming and climate change continues to worsen you’d be forgiven for thinking our seasons are all over place. But is there a fifth season on the horizon and is there a sleeping bag to handle it?!
Season Ratings for Sleeping Bags
Before comfort temperatures and the EN 23537:2016 standard became the norm for assessing which sleeping bag you needed people used the season ratings indicated by the manufacturer. Of course as brands produced a model for European or even global customers the season method became unreliable as the summer season in Italy is a lot different to here in the UK. However the seasons did loosely model towards a range of night time temperatures which you were likely to find in the different seasons in the UK:
1 Season: 10 to 15ºC
2 Season: 5 to 10ºC
3 Season: 0 to 5ºC
4 Season: -5 to 0ºC
The Birth of the 5 Season Bag
So what should a manufacturer do if they produced a sleeping bag with a comfort temperature of -15ºC? Well some just left it as a 4 season bag and assumed the customer would read the specs of the bag and purchase accordingly. Others coined the term ‘5 season bag‘ to clearly indicate to consumers that the insulation performance of the bag clearly outweighed traditional 4 season offerings. So for example the Snugpak Softie Expansion 5 is well known for being called a 5 season bag. Rab’s range of Expedition sleeping bags would be another great example.
Such high performance sleeping bags are also known as mountain or expedition sleeping bags. Generally they will use a down filling but you can get cheaper versions such as the Expansion 5 with synthetic fill however they are very bulky and are mainly used for fishing who users don’t always have pack size concerns like trekkers or backpackers.