Wind direction, conventions

-- Last Updated: Oct-18-07 11:02 AM EST --

On VHF NOAA weather channels, when the report says 'South Wind,' does that mean coming from the south?

Similarly, for online weather reports like Weather Underground, , or the National Weather Service,, or NOAA buoy,, is the wind coming from, or going to, the reported direction?

edit: It's nice and blustery this morning, and comparing the actual to reported at my house, it's definitely coming from the south, and NOAA, WU, NWS, all roughly agree on South wind, so that probably answers it. But I've never seen the convention stated in writing.


wind direction is always given in the direction it’s blowing from—ie a south wind blows from the south to the north etc. You should also be aware that on NOAA marine forcasts the wind speed is in knots, not mph—20 knots=approx 24 mph.

It’s good to get a definite on that.


NOT always…

offshore and onshore wind comes FROM where?


Weather Reports in Strange Locations
just a point about weather reports and wind directions, speed, swell height, etc.

I use the NWS and NOAA forecasts a lot and they are usually really pretty accurate. Recently on a trip, I got NWS reports from a recorded phone message service. The reports were very very different than local conditions. Unfortunately when you in a strange location the weather reports are more important because you can’t judge the signs of what is going on in the sky and water with what the ultimate outcome will be without some local experience.

Also on islands and peninsulas people will take anything towards the mainland as west etc … when in reality it is north or south …I had this happen to me in coastal waters in Virgina once …it took me two days to figure out to ask what people meant by “west” and “east.”


– Last Updated: Oct-18-07 1:16 PM EST –

In terms of compass direction--NOAA always indicates the compass direction of the wind and this is the direction it is blowing from----but some other weather services might use the terms onshore(blowing to the shore from the ocean) and off shore(blowing to the ocean from the land) I've never heard NOAA use these terms in their marine forecasts---it's always a compass direction. PS---I just checked weatherunderground, they use compass directions---never have heard the terms onshore and offshore used in official forecasts NOAA or NWS---I have heard them on television to describe the winds but always with the compass direction added--to wit: "SW onshore winds at 10 knots"

air weather service
From three years as a weather observer in the Air Weather Service stationed at Minot AFB North Dakota I observed and reported on plenty of winds. When we reported winds NW at 15 knots it meant the wind was blowing out of the NW at 15 knots. The National Weather Service always reports the direction from which the wind is blowing.

Windward, Leeward
While we’re discussing conventions for wind direction, I just got it clear recently that windward is into the wind, and leeward is down wind. For a wind break, island, etc., the windward side is the exposed side, the leeward side is the protected side.

For example, in 30 knots wind, a fellow kayaker might shout, “LET’S HEAD FOR THE LEE OF THAT ISLAND!,” followed by the response, “WHAT? I CAN’T HEAR YOU!”


but what about
a Lee shore of an island?

this is actually the windward side of the island. in this case Lee describes the relationship of the wind on the vessel.


Somewhat off the Subject…
If a synthesized voice on your VHF radio says the winds are going to get calmer, but a woman from the coast guard tells you in person that the winds are going to pick up… trust the woman.

ask LeeG

It is the opinion…
It is the opinion of Bob Dylan that:

“You don’t need a weather man to know which way the wind blows”.

I apologize; I couldn’t resist.


You will also hear
NOAA refer to strong localized outflow winds in places like Alaska, BC etc.

For example: Vancouver Island North…ridge of high pressure will persist with NW winds 20-25 knots in the afternoon with potentially strong outflow winds at enrances… otherwise referred to as Catabatic winds which can be in excess of 50 knots. A localized phenomenon often called out on the forecast…at least out here.

Other terms of interest: Veering and Backing - Veering is wind direction shifting clockwise whereas Backing is wind direction moving counter-clockwise. Fetch: The distance the wind can travel unobstructed = more waves. Example of this is crossing a bridge during a blow…choppy on the windward side, calm to lee but the further one gets from the wind break the longer the fetch…the bigger the seas.

More on wind

– Last Updated: Oct-18-07 5:21 PM EST –

NWS uses the Beaufort scale occasionally. Irishman Sir Francis Beaufort created the scale in 1805. He didn’t scale wind to speed but rather, and more importantly, to its effects since wind force is the velocity squared, or something like that. For example a 20mph wind is not twice as strong as a 10mph wind, it's four-times as strong.

You dont want to paddle the lee shore
in a high wind. Thats where the waves break because of the fetch.

You want the windward shore and hide in the wind shadow.

to really make things complicated you want to paddle in the lee of the windward shore–lol

At home, the NOAA forecasts are usually fairly accurate. At Lake Powell recently, they were often way off. We gave up using the forecasts and just did without 'em.

Let’s see if I understand.
In this case, “lee shore” describes the direction of shore relative to the vessel and the wind. The statement says that the shore is leeward (down wind) of the vessel. Is that right?


Though I found in high wind

– Last Updated: Oct-18-07 10:54 PM EST –

that paddling very close to the lee shore of a bay, for example, if low fetch and waves aren't an issue, will give you _some_ protection from the wind. I think the shore puts the breaks on the wind and the higher pressure backs up a bit into the water. It's considerably less windy 10 ft from shore than say 100 ft, even though you're windward of the shore.


If the wind is coming from the west, a west wind, you want to be on the shore the wind is coming from; the windward shore.

Islands are different; the windward shore is between you and the island…the island isnt helping you.

Anyway I was able to paddle up Agnes Lake in Quetico in 80 kt winds with no problem. The wind was coming from the west. The land gives you some protection (there was an elevation on shore of about 20 feet) so the wind shadow extended about 30 feet from shore. A mile to the east the waves were breaking on shore 20 feet up.