Why Your Region Looks Cloudy Today, and What to Do About It

Short version: the satellite cannot see water through clouds, so a cloudy day leaves holes or a blank patch on the chart. That is normal. Switch to the composite view or the cloud-free view and you can usually still read the water.

Why clouds blank the chart

ReelTemps builds its temperature and color maps from satellites that read the ocean surface from space. That is how you get best-in-class satellite data from NOAA and NASA JPL on your screen. The catch is simple physics: those instruments see the top of the clouds, not the water underneath. Where a cloud sits between the satellite and the sea, there is no good reading for that spot on that pass, so the chart shows a gap.

This is actually a feature of an honest product. Rather than paint a smooth, invented color over a hole and pretend it is real data, the chart shows you where it genuinely could not see. A blank patch is the chart telling you the truth.

A few things worth knowing:

• It is weather, not a bug. A storm front, marine layer or overcast stretch will leave the same gap for everyone looking at that region.
• It moves. Clouds drift, and new passes come in throughout the day, so a region that is blank this morning may clear by afternoon.
• Quality matters. The SST uses only confidently clear pixels. Borderline, hazy pixels are left out on purpose, which keeps the picture trustworthy but can also mean more gaps on a marginal day.

Fix one: the composite view

The first and best move is the composite view. A composite blends several recent satellite passes into one picture. A cloud that blocked one pass usually was not sitting in the same place a day earlier, so another pass fills that hole. The result is a continuous read of the water instead of a checkerboard of gaps.

• The 3 day composite is the default for a reason. It fills most cloud gaps while still showing the water as it is now.
• Widen to a 5 or 7 day window on a stubbornly cloudy stretch to pull in more passes and fill more of the map.
• Narrow to a 1 day or half day window when skies are clear and you want the freshest read.

The trade off is recency. A wider composite fills more holes but blends in slightly older water, so an edge can read a touch softer. Our full breakdown is in composite vs single pass.

Fix two: the cloud-free view

When clouds are heavy and even a wide composite leaves holes, switch to the cloud-free view. This is gap-filled imagery that gives you a usable, continuous picture on a day the raw passes simply cannot deliver one.

Use it to keep reading the broad pattern, the general location of the warm and cool water and the rough line of the break, when the honest raw passes are too broken up to work with. Just hold it a little more loosely than a clean single pass, since the filled areas are an estimate of the water, not a fresh direct read of it.

Fix three: check the true color image

If you want to see what is actually going on, open the true color layer. That is the real satellite photograph of the ocean, clouds and all. It will not give you a temperature on a socked in day, but it shows you exactly where the clouds are and how much of your region they cover. Sometimes you will see that the clouds sit inshore while your offshore grounds are clear, which changes the whole plan.

Fix four: lean on the buoys

On a genuinely blind day, the buoys earn their keep. Buoy stations report real in water temperature, wind and wave readings regardless of cloud cover, because they measure from the water, not from space. They will not map a break for you, but they give you hard numbers at fixed points to anchor your read.

Remember that satellite and in water readings can differ, so treat the buoys as ground truth for a point, not as a second opinion that must match the chart exactly. Buoy coverage applies to U.S. regions. More in ground truth SST with buoys.

What to do, in order

Here is the quick routine when your region looks cloudy:

1. Switch to the composite and start at the 3 day default. 2. Widen the window to 5 or 7 days if gaps remain. 3. Try the cloud-free view for a continuous picture when passes are too broken up. 4. Open true color to see where the clouds actually sit. 5. Check the buoys for hard in water numbers. 6. Come back later. New passes arrive throughout the day, and the region often clears.

A cloudy chart is frustrating, but it is honest, and you have tools for it. Pull up your region on the charts, whether that is Northern California, Gulf of Maine or anywhere else, and work through the list before you write the day off.

Not for navigation.