Trade Winds

Once a geek, always a geek. No matter if it was CB radios when I was a kid, or computers in high school through today, I’ve always been a nerd who is interested in the way things work. I’ve also always been curious about the weather, in the same vein. (Groan, a pun — more evidence of geek.) Anyhoo, given all that, it is no wonder I am fascinated with this new climate of ours here in Hawai’i.

The weather here is, more or less, the same throughout the year. Even though it is winter, we have just had several days that were hotter and more uncomfortably muggy than the days we experienced on a visit last August. We’ve also had some days since we arrived this year that were the most luscious you can imagine: cool breezes and an oh-so-slight chill on your skin while in the shade… and warmth in the sun that reminds you of a hot towel coming out of the dryer in an overly air-conditioned room. It’s a sultry mix that allows you to move into your own private microclimate of choice, depending on if you decide to walk down the sunny or shady side of the street.

It really got me wondering what it is that causes that perfect weather here. Turns out, it is a very simple and elegant answer, and one that I had heard of before but did not really learn about in depth until we moved here. It’s the effect of the so-called trade winds.

The trade winds hit the Hawaiian Islands from the northeast, bringing with them cool temperatures that mix with the hot air more typical of this latitude, creating that perfect mix of hot and cool. When they are blowing, life is perfect. And I mean absolutely perfect. When they go away, it is like a wet, hot, slowly smoking humidifier takes over your world.

Strangely, I found it hard to find a good weather app that would tell me when these trade winds would appear or disappear. The local TV forecasts do an OK job of mentioning it from time to time, but being the geek I am, I wanted more. I wanted to see for myself a prediction of the winds, on demand.

Fortuitously, I happened to see while watching our favorite sailing couple on YouTube (Sailing La Vagabonde), a computer screen of the weather program they use. It is appropriately called, Predict Wind, and I am in love with this thing.

Let’s look at a phone app screenshot of Predict Wind from yesterday, which will show us graphically why it was so awful then.

The important things to look at are the colors and the little stick figures (or lack of them, represented as circled dots). Here you can see from the legend that the purple color means almost no wind speed, and the blue is less than five knots (a knot is about 1.15 mph). The little stick figures are called wind barbs, and, when wind is present, they indicate the direction from which the wind is blowing. It’s pretty stagnant on Oahu in this picture, as there is no clear direction of a strong wind.

By the time Friday rolls around, the trade winds are going to be back! Predict Wind’s screenshot below clearly shows this, even to a weather layperson.

Now are are talking! Fifteen to 20 knot winds coming from the northeast. Once the wind hits the island and makes it over the mountains to us, it turns into that wonderful breeze I was mentioning earlier. If this forecast holds, we are going to be loving it on Friday.

I am going to be using this app/website all the time. It now sits alongside my other weather app of choice and will comfort me on those muggy days when the trade winds are nowhere to be found.



P.S. We really feel for our family and friends back in the New York area who may be reading this during the biggest snowstorm of the winter. We hope it blows over soon, and safe journeys to you all who have to trek through it.

Illustration by Jessica



6 thoughts on “Trade Winds

  1. Love the post John- I am also a weather geek and find it fascinating. Leeward and windward side of the islands also help me understand weather patterns. Usually drier on leeward etc.. Get a good barometer and then you can watch rising or falling pressure:)

    Awesome illustration Jess –
    love P


    1. Thanks from both of us. You would likely appreciate Predict Wind since you sail. The complete version has route planning and all kinds of bells and whistles. I went for the $30 per year version that doesn’t have all that sailing specific stuff.


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