That's what wood does. What is the stain type and finish you are using?

This^^^^ We had a mahogany wood front door in our previous house. It was under a porch but the sun came in under the porch that faced east. The door had to be redone every year. The sun and weather do a number on wood.

vinmarks - Our mahogany front door faces East and still looks great! At our previous home, our front door went for years without having to be re-done. It did need refinishing by the time we moved after 15 years.

millworkman - I knew someone would ask what the painter used, and then we repeated. I will have to go down into the utility room underneath the house and dig out the cans. In the meantime, do you have a recommendation of what to use. We can re-sand and start over. Remember, the house is less than a year finished. Having to redo the railings after just a few months in, and then again a few months later, does not seem right.

Our T&G pine porch ceilings have the same finishes, and they look great. I suppose because they do not get direct sun.

I wonder if there is some sort of stained look, smooth, Faux board that we could attach to the top of the railings.

Azek would be the choice. Mahogany does not take stain well on the flat or sealant or sealant for that matter.

You will need to sand lightly and clear coat this handrail every six months to keep it looking good, and a sand to bare wood every few years. Mahogany handrails are a luxury detail that is high maintenance. It’s the Italian sports car of handrails. Pretty, but so much work.

Azek is junk compared to mahogany. It expands and contracts like crazy and you've got to accommodate that with large ugly gaps or it buckles.

HALLETT & Co. - It hasn't even been 6 months between the last two rounds of stain and urethane. And just sanding off the clear coat would not work because the stain is fading. What staining/sealing products do you recommend we use?

millworkman - I told my husband my idea of putting something like Azek on the the top of the drink rail and he was not a fan. He said it was ridiculous to cover-up the mahogany that we paid so dearly for. I had found THIS product to show him.

Joseph Corlett, LLC - Thank you for pointing that out about these faux wood products. Looks like we will be sanding and re-staining/sealing every 4-6 months!!!

I suppose we could paint the railing white like we did on our back screened porch (also mahogany wood), but we love the railing with a darker finish on the front.

You should certainly be getting more than six months out of it.

I would recommend Epifanes or Total Boat Lux. They should extend the life significantly.

Not seeing where OP stated it was polyurethane, but maybe I missed it. Spar varnish (aka marine varnish) is said to be a more durable outdoor finish, more UV resistant and waterproof. Be sure to complete remove the gray weathering and mildew (black stains) before sanding/refinishing ( w deckwash or TSP+ bleach ) . Maybe the spar will be more durable - at worst if its an annual spring ritual at least it wouldnt take long - only top surface. ETA - didnt see Brys reply before posting, thats what I meant to say LOL.

bry911 and Debbie Downer - Thank you for the recommendation. Now to find out where to purchase the marine varnishes.

Oh, and Debbie, I can assure you that the black is not mildew. It's what is left of the Dark Walnut stain that has not faded. We wipe down the railings after a rain IF there is any standing water. Only one railing seems to get a little standing water, but they dry out very quickly after a rain.

Here is what the railings looked like after we refinished in mid April.

Find a wood finisher who can use a topnotch UV resistant finish, such as is sold for marine uses.