this is a subject dear to my heart, since I spent so much time doing this each spring in Europe. Unfortunately, there is little cold rain here in Nevada. But just last week, we were lucky to have an arctic storm move in and I finally got to test my new armless poncho design. Pouring rain all day turning to snow by the evening, strong winds from the west, temperatures about 35°F initially and then dropping into the 20's by evening. The poncho worked like a charm! I was wearing it over 2 of my supplex shirts zipped to the neck, and with the hood tucked under my fur felt wide brim hat, no gloves or mittens, supplex pants and running shoes. I felt warm the whole time. The poncho keeps everything dry down to mid-thighs (though the taslan wicks above that level) and also fully protects the hands, so no need for rain mitts. The hood stops all air movement at the neck, which is probably the reason I was warm with just the supplex shirts.
The problem with armholes on a poncho is that these inevitably leak both water and wind. And to what end? To allow free use of the arms? But a poncho is already such a cumbersome thing that the armholes don't really help that much. I figured this out on my last trip when I sewed up the armholes I was using then. But that left two flaps at the shoulders (because the poncho is squarish rather than semicircular) that flapped annoyingly. Also, my poncho this last trip was silnylon and so wasn't too comfortable in warmer drizzly conditions, especially going uphill. So I decided to use Goretex instead. This increases the weight significantly, but also greatly increases the range of conditions in which the poncho can be used comfortably. In particular, it allows the poncho to be used for protection from wind as well as from rain.
Like I said, I tested the armless design my last trip with the sewed up silnylon poncho, and I found it quite easy to move about while wearing it, other than while rock climbing. In particular, I was still able to use my walking stick, but with my hands protected from wind and rain, and reach my other hand out from under the poncho to grap at things. There were times when I needed both arms free or I wanted to avoid the poncho flopping around in front of me when I bent over. So on this new design, I added a feature to allow me to gather up the front of the poncho and snap it in place. This way, I can work with both hands in front of me and bend over without the poncho getting in the way.
The design couldn't be simpler, though sewing the flat-felled seams might be tricky for a beginner (sorry I don't have pictures but I can't justify buying a digital camera at this point, however it is easy to visualize from the diagrams):