About a year ago, I took this video along the Hudson river in NY, and I'm trying to figure out the Beaufort number based on the water and the flags.


The problem is that the Beaufort scale is based primarily on open sea waters (not protected/inland waters like the Hudson river). The only mention in the scale relating to inland waters is force 5 ("crested wavelets (whitecaps) form on inland waters") - but nothing related to the higher force numbers.

In this video, there are definitely lots of whitecaps, which leads me to believe that the wind was force 5 or higher. Possibly even a 6.

Flags are another indicator; but here it is kind of vague. At force 5, flags start rippling and flapping hard, and as the wind gets stronger, they start beating/snapping, until finally they are fully extended with only the very end flapping (force 7). So looking at the flag in the video makes me think it's a 6.

What steady force/speed is the wind really blowing here? What about gusts?

  • $\begingroup$ I haven't spent too much time on the Beaufort... but while you're right that inland water ways will be reduced some, I'd think the Beaufort Scale still is indicative of the winds in the area... the winds are less not just over the water but over the inland area as well, such that the flags give an idea of local winds still. For instance in hurricanes the strongest winds are just about always measured by hurricane hunters over the ocean, because winds reduce even over short amounts of land. But I can't speak more to any decent estimates. $\endgroup$ Commented Oct 29, 2018 at 20:58
  • $\begingroup$ You could try to dig up the observation reports from Central Park if you happen to know the date the video was taken. It's obviously more towards the center of Manhattan, but think they might be a tiny bit more representative than Kennedy/LaGuardia/Teterboro/Newark (which you can also get obs for), though any would probably be useful comparisons. $\endgroup$ Commented Oct 29, 2018 at 21:01
  • $\begingroup$ Are you sure you want answers solely based on water and flags? Your video shows more objects, and shore objects are also good indicators (think: trees). $\endgroup$
    – Jan Doggen
    Commented Oct 29, 2018 at 21:48
  • 1
    $\begingroup$ Thanks - the Weather Underground site shows the wind at 15 mph gusting to 28 (so force 4 gusting to 6). Earlier that day the wind was 19 gusting to 39 according to that site. $\endgroup$ Commented Oct 29, 2018 at 23:06

1 Answer 1


I would call that about a force 3. But be aware that one of the problems near shore is that the shoreline, buildings, and topography have a large effect on the local winds - both direction and speed. Also fetch makes a difference - waves don't have enough time/space to build to their full size without sufficient fetch. Not the case in your video but it is difficult to evaluate waves when looking downwind because you see the less-steep backs of the waves and maybe only the tips of the whitecaps.

Sea kayakers have some decent resources for estimating winds near-shore because most kayakers spend the majority of their time in that environment. Here is one example.

  • $\begingroup$ I would consider the wind at the flags to be closer to 4. Inland does make it more difficult additionally, you cannot use the sea state to determine the wind in this case because the wind is clearly localized to the area. If you look in the distance the wind appears to start a few hundred meters off shore, so the sea state will not be indicative of the wind speed. $\endgroup$
    – user824
    Commented Oct 30, 2018 at 15:33

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