For me, when cold weather comes, and the nights clear and I can get out to observe, getting dressed and having the right clothing is essential for having a successful night. Nothing will kill an observing session in the winter on a fantastic night then if you get cold. So the objective of this post is to share what I do to keep warm and I hope then, it helps you to know what to do to stay warm on those cold winter nights.
The first layer I put on is a Merino Wool base layer that I get from a company called Minus33. I purchase and wear the Expedition bottoms and top for a base layer made from Merino Wool. This wool is not itchy and does an outstanding job of whisking moisture away from my body. These base layers are not cheap, they run about $100 each but for me, are well worth it. Besides astronomy, I also use them when I snow shoe.
From here I'll start with my feet and work my way up. On my feet I first put on a base layer of either silk or wool sockings. Over that I put on a Expedition Level Merino Wool winter sock from Minus33. You can see those socks here.
I find that the combination of a silk or base layer sock, and a high quality, thick Merino Wool socks keeps my feet dry and warm. THAT is essential for me to stay dry and warm and in the field. Over this I wear an excellent snow and waterproof boot. Again, the boot I wear in the field for astronomy is the one I use to snowshoe. I own an older pair of Sorel boots, but based on a lot of reviews I have read online about their current boots and the fact that they do not last that well so I have opted for a Keen boot from REI. My boots are insulated down to -50 degress F and fit just fine (they were initially needing to be broken in but I did buy a shoe size one higher than I usually do, I usually get a 12 so I got a 13 and with my wool socks these fit perfectly). Here are the Keen Boots I own. They are the Keen Neve Winter boot and they are great for keeping my feet dry and warm, be that snowshoeing or in astronomy.
These are on closeout with a cost around $130.00 and these other Keen boots are in the same price way, the Keen Summit Winter Boot.
The key to your boot is that it must have sufficient insulation to keep your feet warm, adequate space for your foot with wool socks on and comfortable enough to wear for the evening. They also must be waterproof and for me, stay laced during the night.
Next we'll move to my legs. Over my Merino Wool base layer form Minus33, I wear a fleece pair of pants and then it depends on what I am going to wear. I have a pair of fleece pants from REI and another from Cabelas that I can wear. Over that, if it is really cold I usually wear a nice pair of heavy fleece sweat pants. Next, I have a pair of snow pants, actually two pairs that are extremely warm. They are from Columbia and I have worn them in the field and they work well. I also have a a couple of pair of hunting bibs. I am no longer a hunter, but hunters who do duck hunting in a blind, or stand hunting in a tree, know what to wear to keep warm. You may not like the camo look, yet if you can get pass the camo look, that line of clothing will keep you warm, very warm.
So you can wear like I do sometimes, wool socks, wool socks, fleece pants, fleece or wool pants or sweats then snow pants, or you can wear the base socks, wool socks, snow/winter boots, base layer on the legs, fleece pants. sweats then fleece or flannel or wool pants or sweats, wear the upper body items that I'll go through and then bibs as you can see here from Cabelas.
The bibs are waterproof, insulated and it is important if you use bibs, to have the kind that unbutton on the side of the leg and then unzip up the side of the legs to allow you easy access in and out. I also recommend buttons on the bottom of the legs where your feet come out so they are enclosed. A zipper for relieving is critical also and good clips that connect the suspenders. I wear my bibs about 90% of the time I observe, except in summer unless I am up in the mountains. I do often have them with me in late spring and summer in case they are needed. I love my hunting bibs and they are warm, VERY warm.
On my upper body or torso I wear the merino wool base layer from Minus33. I then have short sleeve shirt I wear over that, then a long sleeve fleece shirt. Over that goes a Merino Wool sweater like this one from Cableas, and then a fleece zip up jacket like above from either Columbia or NorthFace:
Or if that sweater is unavailable I wear this Peregrine Merino Thick Wool Sweater from Sierra Trading Post LINK. I like this sweater as I will wear it around the house and for casual dress, and when I observe.
Over all of that upper body now goes either my hunting parka from Cabelas, or my X300 Guidewear Parka which is designed for Ice Fishing or fishing in winter. Here are those images.
The Hunting Parka above is insulated, VERY warm and has plenty of pockets for eyepieces and other equipment that you can store in all those pockets. It is rough and I have had mine for 3 years now and no wear or tear is evident. It takes remotes sites here in Utah extremely well.
Above you can see in them middle my Cabela's X300 Guidewear (my is discontinued). It is 100% waterproof, insulated and thus VERY warm; has four pockets behind those two upper zippers, two large pockets on the bottom, and two side zipper pockets. The neck is fleece to provide comfort there. Again, if dressed correctly, this is VERY warm. Either option, the Hunting Parka above with about the same number of pockets and probably just a tad more insulation or the X300 ensures that I am warm no matter what I am doing in the winter. The hunting parka I usually use observing, and the X300 is usually my snowshoeing parka though I do have another parka I can use for that also.
On my head I always have a nice cap on my head (though it is false you lose most of your heat from your head, it is about 20% of your body heat). I keep that cap on while I am setting up, and then put on my merino wool baklava from Minus33 which you can see here.
This baklava will pull down under the chin, pull up over the mouth, or just allowing the eyes to see out. Over this I put a hat back on that is wool and sometimes I pull the hood of the parka up and over if I want to use it to shield my eyes, though at a dark site, that usually isn't needed.
The last item of clothing needed are gloves. I actually have like 4 different pair of gloves. I have a pair that are warm, but allow a great sense of use. You can see those gloves here.
After these, I move to using merino wool glove liners that keep my fingers and hands warm.
These are from Merino 33 again, and they do keep my hand warm, especially if I have to remove my gloves to sketch.
I also have a pair of heavy duty gloves that I wear with the wool liners when I snowshoe. They are warm, the warmest gloves I have but they are also bulky. However as one of my observing nights got down to around -5 degrees F, these gloves made a HUGE difference in keeping me warm to observe.
So there you go. That is basically what I wear. In the summer I wear my base layers, and usually two layers on my legs and a couple of layers on my torso and a good winter coat as even in the summer, nights in the West Desert of Utah can get in the upper 30's F and in the mountains of Utah, easily in the 20's F. So yeah, keeping warm is important, even more important now that I am in my 50's and having lost 85lbs so far ensures that I am colder than I was when I had more insulation. So figure out what works for you, and yes, in my case I spent money to stay warm and for me, that is money well spent. How much you spend, what you buy, how you stay warm, that is up to you to figure out. Good luck and keep looking at the wonders of our night sky!