When temperatures drop and your only protection from the elements is your bivvy, it makes sense to maximise your comfort. Feeling cold and damp will do little to enhance your enjoyment of your fishing trip and could see you heading for home ahead of schedule.
Use your bivvy wrap
any bivvies are supplied complete with an overwrap. This will provide a valuable additional layer of insulation while reducing condensation and damp inside the bivvy. Condensation forms when your body heat raises the temperature in the tent and moisture condenses on the cold surface of the bivvy. You won't need the wrap in warmer weather as condensation won't be a problem but in the winter months, peg over the wrap, making sure that there is a gap between the wrap and the bivvy.
Use a groundsheet
A groundsheet is essential in cold weather. Preventing the dampness in the ground from entering the bivvy while providing additional insulation, it could make all the difference to the environment inside your bivvy. Tuck your mud flaps under the groundsheet to reduce draughts. A groundsheet will also keep your bivvy free of mud and dirt.
Peg your bivvy correctly
It pays to keep more than one set of pegs for your bivvy. Shorter pegs are useful for firm ground while longer pegs are must-haves for both softer ground and windy conditions. Always ensure that your bivvy is securely pegged and that the fabric is taught. If you are using a wrap, it should be as taught as you can get it and must not touch the bivvy.
Pick your spot wisely
Pitch your bivvy on the driest area of the swim. In good weather, you will want to position your bivvy facing your rods but this might not be the best choice in winter. If there is shelter to the right or left of the swim, position you bivvy so as to take advantage of the protection from the wind afforded by the foliage.
In the coldest conditions, you may require additional heat in order to keep warm and to sleep well. But safety is a major issue. Anglers have lost their lives using inappropriate heaters which have leached carbon monoxide into their shelters or even blown them up. Naked flames are clearly a bad idea so choose one of the latest bivvy heaters which are safe and designed specifically for use in tents. Hand warmers will help revive frosty fingers and a hot water bottle is an old-fashioned but highly effective way to keep warm.
Choose the right sleeping bag
Invest in an all-season sleeping bag or choose an insulating bag for the winter and lighter style for the summer months. Before climbing into your bag, remove some layers of clothing. It's counterintuitive but stripping down will keep you warmer. Your body heat will warm up the environment inside the bag and the technical fabrics used for the shell and fillings will keep the heat in. You will feel more comfortable sleeping with less clothing on and you will gain more benefit from the extra layers when you put them on in the morning. If you still feel cold, place your extra layers over the bag like blankets.