Cold weather is hard on almost everything, and the engine in your car is no exception to this rule. The most common problem with why your car will not start in cold weather is that batteries literally freeze up, causing the electrical charge in them to do the same. There is also air/fuel ratios that need to be addressed here. It takes more fuel to ignite cold air than it takes to ignite warm air. Then there is just the plain fact that the fluids in the engine can be frozen, siezing it from the inside. We are going address each of these situations and find out what can be done to prevent them from happening.
Starting with the battery, the electrolyte (battery acid) does not hold a very strong charge when it is frozen and it can cause some slow engine cranking problems if it is not completely frozen, and doesn’t even have enough “juice” let the starter solenoid click when you turn the key. If this is the case, then a jumpstart is very likely to help get you on the road, but be aware that if a battery is ever allowed to be discharged below 10 volts, then it can (and usually does) damage the battery, and it will not hold a charge again. This situation can be prevented by wrapping the battery with insulation and/or getting a battery with a higher Cold Cranking Amp (CCA) rating. I use 750 CCA batteries, and have never had any problems like that, in freezing temperatures.
Older carbureted engines had what is called a ‘choke’. The purpose of that choke was to not let as much air into the engine, while it was cold, and gradually let more in as the engine warmed up. Today the job of the choke is done electronically with sensors and a computer. If one of the sensors that measure temperature on your engine is messed up, then it will almost certainly cause cold weather starting problems. The Intake Air Temperature and Coolant Temperature Sensor are the main sensors that provide this information to the computer. Another thing that can cause too much air to enter the engine, to ignite the cold fuel mixture is the potential for vacuum leaks. Vacuum leaks are worse because they actually let unmetered air into the engine which can eventually damage major components. So to prevent any of these from happening, you will need to make sure your engine stays in top running shape, and immediately address any engine light issues.
The likeliness of freezing all of the fluids in your car is not very high. However it does happen and is very possible. There is not much you can do about this except for either parking the vehicle in a garage, or installing oil, and coolant warmers on the engine. Oil warmers go on the oil pan, and coolant warmers (more often called block warmers), go into the engine block into a hole of one of the freeze plugs. You plug these warmers into a normal house electrical outlet and they warm your engine up after a few minutes usually. It is best to have them plugged in and working so that nothing is allowed to freeze up inside the engine anyways. This is because when things (like water) freeze they tend to expand, and this expansion can actually crack the entire engine block, instantly rendering it useless. Another thing to keep in mind about freezing fluids is that brake fluids absorb water, and if your brake fluid has done this, then it can freeze in the lines causing you to not have any brakes!
Now you have a good idea of what can make your vehicle not start in cold weather, and what you can do about those things. Take this knowledge and use it to help someone else, as I am doing for you. Thanks for reading, and stay warm.