This article is from the Running FAQ, by Ozzie Gontang with numerous contributions by others.
("The Running Book" By the Editors of Consumer Guide)
Cold weather does not present any serious problems for you, especially if
you are in reasonably good condition. If you have heart problems, consult a
doctor first. High wind-chill factors are the greatest threats to you in
cold weather, since you can suffer frostbite if you are not adequately
protected from the wind. You must remember that when you run, your own
motion against the wind increases the windchill factor and increases the
risk of frostbite. Be sure all normally exposed areas of skin are covered:
head, face, ears, and hands. The important thing to remember is that you
must dress in layers in order to create your own insulation.
When you run in cold weather, beware of ice on the road, and remember to
taper off your run slowly so you will not catch a chill. When you arrive
home, change out of your damp, sweaty clothes right away.
When you run in hot weather, your blood pressure can drop dangerously or
you could suffer heat exhaustion. If you start feeling dizzy and dehydrated
while jogging and your pulse and breathing grow very rpid, you could very
well be on your way to heat exhaustion. Stop exercising immediately. Get
out of the sun, drink fluids (tepid, not cold), and rest.
Running in heat also slows down the blood circulation, placing a greater
burden on your heart. And of course, you will sweat a lot more so your body
loses more water that usual. To replace it, drink a full glass of water
before you start and one every 15 or 20 minutes during your run. A few
pinches of salt dissolved in the water will help. But if your stomach is
empty, omit the salt or it will probably cause stomach cramps.
An important thing to remember about heat is that it takes your body about
two weeks to adjust.
If you run in a strong wind, you are going to be expending six percent more
oxygen that you would under ordinary condtitions. So, if you are running in
a stiff breeze slow down and you will get the same benefits as you would
from a faster run. When you set out on a windy day, start with the wind in
front of you at the beginning of your workout; then at the end, when you
are more tired, you will have it at your back, helping to push you along.
Rain need not be a deterrent unless you're afraid of melting, but you will
need some protection. Wear waterproof outer clothes, of course, and as many
layers as you need to keep warm. Don't linger in them after the run but get
into dry things as soon as you get home.
High altitudes are a source of special problems. When you get to 5000 feet
above sea level and beyond, it takes a lot more time for oxygen to be
absorbed into your blood and travel throughout your body. So your heart has
to work a lot harder at its job. Plan on taking at least four to six weeks
to get adjusted to a new high altitude, and adapt your jogging routine
accordingly. Most runners recommend cutting your program by about 50% at
Running on cold, rainy days (Brendan Leitch firstname.lastname@example.org)
1) Dress in layers
2) Keep DRY, this is done by putting the wicking layers closest to the SKIN.
What works for us: (us = the running club I belong to)
Top: 1st LIFA or some similar 'wicking' material against skin 2nd turtle
neck or long sleeve t-shirt(repeat if needed) 3rd Shell jacket, Goretex is
best, but any layered Nylon one will do the job
Bottom: 1st LIFA or some similar 'wicking' material against skin 2nd long
3rd wind pants(preferably goretex again, but nylon will do)
Head: 1st Bella Clava(a thin hat that goes around head like old fashioned
2nd Your shell jacket hat over the Bella-Clava
Hands: 1st light thin wicking material gloves 2nd heavier glove
Feet: your normal socks/shoes - just make sure your bottom clothes cover