Afghans can be all different weights, sizes and fibers.
In my experience, the warmest afghans are made of animal fibers such as wool and alpaca. This especially holds true if the afghan will be used in some sort of capacity where it or its wearer could get wet -- for example, people riding in a sleigh, sailing in a sailboat, or dealing with a leaky roof in the bedroom. Wool and similar fibers such as alpaca and bison stay warm even if they get wet. Many other fibers, including cotton, do not have this property.
I've found that solid afghans tend to be somewhat warmer than afghans with open spaces. So for those of you facing truly arctic conditions in winter time, an afghan comprised of solid stitches is the way to go. Check out any of these free patterns for ideas:
- Custom crochet afghan pattern
- Gingham check afghan
- Heart sampler baby blanket
- Coral hearts baby blanket
For those of you who are surviving California-style winters rather than Alaska-style winters, my experience has been that granny afghans and other afghans with open spaces have always been plenty warm enough in the past.
Since you never really know what the weather will do in the future, it's a great idea to have several warm blankets on hand for each family member -- no matter where you live. That way, if there ever comes a time when it's colder than expected, you can simply layer a couple of blankets on and beat the chill.
Another good idea: if you drive, stash a warm blanket (or several, if you have a big family) in the back seat or car trunk in case you ever break down or get stranded in the cold.
Additional Resources for Making Your Blankets:
I hope y'all are staying warm and dry out there. Happy crocheting!