What's a persistent weather condition that could justify being unable to use the Sun to obtain a bearing?

Question

I'm attempting to plot an unplottable piece of land. The basic idea of the concept is that travelers who end up within the land will get lost because there's simply no way to get one's bearing, except keeping very meticulous track of where they've been. (Which is basically impossible if you get chased onto it, because laying down a trail when you're running for your life is difficult).

The tech level here is roughly Renaissance. The region in question is roughly fifty miles in diameter, and perfectly uniform from surface appearance, with no visible landmarks. It should also be noted that the this is a deliberate choice on the part of the vague and mysterious Keepers of the property, any man-made landmark will disappear overnight. There is also no magic, save for that of the mysterious Keepers stealing your breadcrumbs every time your back is turned.

Compasses exist, but compasses are easy to confuse. There are a large amount of buried caches of highly magnetic metals to screw with the magnetic field, so compasses will kind of work but the margin of error on them is quite unpredictable.

The problem I have is the sky. The planet in question is Earthlike in rotation, spins a tilted axis. That means that you could use the Sun to determine your path, and if you're good enough at math and have the right tools, you can determine true north. The same is, of course, true for astrolabes and quadrants during the night.

I need a way to justify the explanation of 'well the sky's broken so you can't use it to figure out which way is north'. Even something that will give me a few degrees of error is fine, but I need a way to figure out a persistent weather condition that justifies this. If this is not possible on a large scale, working small scale is fine, but I need a way to justify that sentence of 'Well, the sky's broken here'.

Answer 1

Dense rainforest with a thick canopy. Your people would be lost within minutes if they don't know how to blaze a trail.

Answer 2

White out snow fall would pretty much wreck any hope of getting a bearing on the sun. It would also have the useful effect of covering everything with a fresh white layer every few hours, but is unlikely to be persistent.

Perhaps putting the area in a tropical area on a plateau at the right altitude would work. There are some areas of Earth where the cloud, mist and rain are almost continuous and would block any effective means of getting a bearing on the sun. I believe some areas near the Angel falls might fall into this category.

Answer 3

You haven't mentioned much about topology, but a low laying area could have cooler temperatures which causes persistent condensation of water vapor in the form of fog. Perhaps this could be at the foot of a waterfall with an opening at the far end of the valley allowing water to pass. The constant fog created by the waterfall could fill the valley, blocking direct sunlight.

Basically combine stagnant air with moisture and a temperature difference between the air in the unplottable plant and the air in the surrounding area. This should cause cloud cover or fog. That should be sufficient to cover the sun and prevent orienting yourself.