Be prepared for a lot of rain and some snow if you are walking the
Camino Frances in March and April. At elevations over about 700 meters ASL, snow occurs through the end of May. I have seen snow at O'Cebriero in mid-May, and at Cruz de Ferro on three visits, also in mid-May. At the front end, the Napoleon Pass is officially closed through 31 March, and on a day-by-day basis from then. Plan on using the Valcarlos Route.
Also, while daily afternoon temperatures all along the
Camino Frances may hit celsius double digits, like 14 - 16 degrees if the sun is out, assume that at 07:00 when you start out from your accommodations, the temperature will be in the LOW single digits, like 2 or 3 degrees. This goes all the way into May. In my experience, only the afternoon high temperatures vary. But the mornings all start the same...cold, frequently wet, and sometimes white...
Remember, Santiago ain't coming to you. Just waiting for things to warm up is not an option...It is part of the charm of the Camino.
Of course, you could walk in July and August when heat stroke and dehydration are the villains.
That is why layering your clothing is the solution. You start out wearing everything, then peel off layers as the temperatures and weather improve during the day. Keeping your torso, head, feet and hands warm is key to maintaining temperature.
DO NOT FORGET to bring a microfleece beanie / watch cap, and a pair of microfiber gloves. I find mine in my local Target store. Champion makes a brand for runners. But you can find similar anywear. NOTE: The local Target stores here in South Florida do not carry gloves. I buy them when I travel north, or online...
I recommend trying vendors who sell runner's clothing and gears. Don't spend a lot as you will lose these occasionally. I have. Find replacements in sporting stores along the way. My gloves are black but my cap is neon safety yellow.
Also, bring a sleeping bag. I have a very lightweight Sea to Summit down quilt. Here in Florida, and unzipped into a rectangular quilt, it does double duty on the handful of very cold nights (we do not have a heating furnace, only air conditioning). On Camino, I zip it into a tube. One end pulls closed with a toggle. NOTE: Depending on forecast weather, I will forego the sleeping bag in favor of a micro fleece rectangular liner with a full zipper. See:
http://www.alpsmountaineering.com/products/bags
Finally, many albergues and some hostals either do not provide enough heat, or give their systems a shot of heat about 21:00 before lights out, then again in the morning from 05:00 to 07:00 when pilgrims are up and about. It is common for there to be no heat overnight. this is why you take your shower soon after arrival and NOT in the morning. Use your fleece cap and gloves if your head sticking out of the sleeping bag is too cool.
Hope this all helps.
