Where you don't have to replace it? Thought so, try filling it with Bondo. It is the product autos are restored with and more and more DIY and builders are using it for home repairs.
There is also a product which will stop the rot which you can get on line. Don't remember the name of it but I think VanDyke Restorers carries it.
Wood rot is like a fungus that keeps traveling. That rotten wood needs to be replaced, but first you need to address how the water is getting to the wood. We had the same problem and just needed to extend a rain gutter over the door. If it is splashing onto that surface, that needs to be addressed as well.
The wood needs replacing, that is obvious, but more importantly is why it is rotting there. That needs to be addressed asap.
After the source repair is completed and the wood replaced, you could either paint with outdoor paint or cover it with a product called coil. The coil is sold in DIY stores, it is a cover for the wood and you will never have to paint that area again unless you really want to.
Those telling you to replace wood are definitely correct, at least cut that out and fit in treated wood. Then close off your side lights, yes that sucks but I had the exact problem you do ( snow laid in the recesses of side lights) and this was the only solution until replacement could be afforded. I used bath paneling plastic sheets, and framed them to attach them and used silicone caulking to seal throughly! Good luck and start saving for new doors.
Where you don't have to replace it? Thought so, try filling it with Bondo. It is the product autos are restored with and more and more DIY and builders are using it for home repairs.
There is also a product which will stop the rot which you can get on line. Don't remember the name of it but I think VanDyke Restorers carries it.
Replace the rotting section and resolve any places where water might puddle. Get a paint appropriate for outside weather
Wood rot is like a fungus that keeps traveling. That rotten wood needs to be replaced, but first you need to address how the water is getting to the wood. We had the same problem and just needed to extend a rain gutter over the door. If it is splashing onto that surface, that needs to be addressed as well.
The wood needs replacing, that is obvious, but more importantly is why it is rotting there. That needs to be addressed asap.
After the source repair is completed and the wood replaced, you could either paint with outdoor paint or cover it with a product called coil. The coil is sold in DIY stores, it is a cover for the wood and you will never have to paint that area again unless you really want to.
Those telling you to replace wood are definitely correct, at least cut that out and fit in treated wood. Then close off your side lights, yes that sucks but I had the exact problem you do ( snow laid in the recesses of side lights) and this was the only solution until replacement could be afforded. I used bath paneling plastic sheets, and framed them to attach them and used silicone caulking to seal throughly! Good luck and start saving for new doors.
ps don’t buy doors with recessed side lights