Kestrel 4500 Pocket Weather Tracker

By Hollis Easter

11 November 2009, updated 24 December 2009

(click to see full-size image)

As humans, we’re kind of obsessed with the weather. We put money aside for rainy days, make hay while the sun shines, and whistle while the winds of change are a-blowin’. Politicians snow us, and lack of morning coffee leaves us foggy. We might get misty-eyed at the memories of an old love, and we deliver lectures with thunder!

And yet our observations tend to be the earthy, folksy kind. We know less about katabatic air than about trick knees. Most of us know a bit about clouds, and we know enough to get a general sense of what the weather is locally: as Robin Williams says in Good Morning, Vietnam!, “You got a window? Open it!”

Some of us want more. Whether because we’re gadget gurus or meteorology wonks, we want detailed weather data. For me, I guess I’m a pretty serious gear tester at this point–I certainly write about a lot of backpacking gear–and it helps to be able to quote accurate environmental data.

I started carrying an altimeter on winter climbs last year, and I’ve found it an enjoyable addition to my hiking pack. There comes a time during most long hikes when I wonder whether I’m actually making any progress, and it’s lovely to be able to watch my altitude climbing. I assess my fitness level based on how tired I feel after a given amount of accumulated altitude. And, finally, for trailless peaks, it’s nice to know that I’m at the right elevation for the summit to be around here somewhere.

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I’ve often wondered about other environmental data, though. How cold did it get last night? Why was I freezing last night but not tonight? How soon do I think it’s going to rain? How fast was the wind blowing when it blinded me on Marcy’s summit?

Enter the Kestrel series of weather meters from Nielsen-Kellerman, www.nkhome.com . I first read about Kestrel meters several years ago, and I coveted them instantly. They’re what you might call Serious Technology.

Nielson-Kellerman (which, for brevity, I’ll just call “NK” from here out) was kind enough to send me a Kestrel 4500 Pocket Weather Tracker, $409 US, which packs a colossal punch in a Lilliputian package. It’s light, only a bit bigger than my cell phone, is waterproof, floats, has user-replaceable parts, and is warranted for five years of service.

The Kestrel family of meters offers a wide variety of choices for those of us who want to monitor the weather. Several other 4AllOutdoors reviewers are writing about other Kestrel meters, so I’ll focus on the 4500, the flagship of the line.

It’s smaller and lighter than I expected. I was waiting for a big huge box, and I got one the size of a few decks of cards. The device inside is small, but here’s what it measures: wind speed, wind direction, crosswind, headwind and tailwind components, temperature, wind chill, relative humidity, heat stress, dewpoint, wet bulb temperature, barometric pressure, pressure trend, altitude, and density altitude. NK’s specifications for accuracy are impressive, and each meter carries a certificate of compliance guaranteeing its accuracy.

Something I really like about the Kestrel 4500 is that it features a data logging function. I can set it to record data points at preset intervals and, once set, the meter will take weather readings and store them even if I’ve turned the meter off. A clever twist is that I can choose whether to keep storing new data points (and overwriting old ones) or whether to stop when it runs out of memory. I’ve chosen the “stop” function so that I can keep access to my hiking records when I get home. Really cool!

NK also sells a computer interface package ($119 US) for its meters; I didn’t receive one, though I may purchase one later.

The Kestrel came with a pair of AAA batteries, which I inserted as instructed. There’s a plastic shim that fits between the batteries to keep them from rotating once inserted; NK’s manual explains that batteries have a magnetic signature that can interfere with the compass functions, and that shimming the batteries into place allows the meter to compensate for the added magnetism.

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As soon as I put the batteries in, the meter turned itself on. The screen is large (3/4 in by 1 3/16 in) and quite easy to read, even in bright light. I can also turn on a blue-green backlight (using a dedicated button), which makes the screen very legible. (There’s also a night-vision version of the Kestrel 4500 that uses a dimmer red backlight to preserve the ability to see in low-light conditions).

Most of the user interface involves a set of up-down-left-right buttons with an enter button in the middle. All buttons are clearly labeled with icons rather than text, which is nice since the meter’s software offers switchable English, French, German, Italian, and Spanish options. There’s also a menu/power button and a snapshot button, which automatically logs the current readings to the unit’s memory.

This will be a very long review if I keep describing all of the unit’s functions, and I’d like to get to some field use, so I’ll promise to tell you more about the workings of the Kestrel 4500 in a future update.

Field Use:

Ted flies while Hollis measures wind speed on Hurricane (click to see full-size image. Photo by Stephanie Graudons; used with permission.)

I took the Kestrel up Hurricane Mountain with some friends on Halloween. We’d intended to climb a higher peak that day, but the winds were forecast for hurricane-strength (75+ miles per hour) and we wanted to stay at a slightly lower elevation. So we trotted off to Hurricane, a delightful little peak near Keene Valley, NY. Among those on the trip was my friend Ted, a meteorologist who works for NASA. He’s done time at New Hampshire’s Mount Washington Observatory, home of the world’s worst (human-recorded) weather, and has used Kestrel meters extensively. He had serious meter envy.

In the interest of science and gear testing, I stood on the summit like a dork for a very long time while I held the Kestrel meter into the wind. I measured sustained winds of 45+ mph, with a (measured) peak of 54.1 mph. I learned the following things:

• The impeller on the Kestrel works in either direction, meaning I can hold the meter so I can still see the screen.
• The highest winds always come right after I turn off the meter.
• Winds of 54.1 mph will blow me a foot or so backwards if I jump into the air.
• Holding the Kestrel into the airstream for an hour is a highly effective arm workout that becomes even more apparent the next day.

The altimeter seems very accurate as far as pressure altimeters go, and I was pleased to see that (unlike many altimeters) this one actually outputs elevation in increments of one foot. One small disappointment: there’s no altitude accumulation function built into the unit, so it isn’t possible to calculate total climb and descent (just maximum and minimum elevations). However, if I had the computer interface, I could easily calculate the data using a spreadsheet.

I felt pretty warm on the summit, even though the wind was gusting hard, but then I abruptly started feeling chilled. Temperature was the same… winds were the same… what gives? Turns out the relative humidity had gone up suddenly. Sure enough, the rain came soon after.

So who cares? I do. I now know that my “windproof” fleece jacket is effectively windproof at 54.1 mph, which is important to me given that I rely on it to keep me warm when the temperature is -30 F. I’m working on re-calibrating my temperature sense so I’m better aware of what given weather feels like right now, so I’ll feel safer this winter venturing out into bitter cold and serious wind.

To close, there are three other parts of my life (so far) where I’ve used the Kestrel’s capabilities. I learned that the temperature in my bedroom went down to 55 F last night, which explains why I had weird dreams about being cold. The Kestrel calculates headwind and crosswind components, which is handy because I’m a pilot. And finally, the temperature and humidity readings are helpful since I’m a bagpiper and need to adjust my reeds for the changing air of winter.

Thank you, Nielsen-Kellerman, for letting me review the Kestrel! I’m looking forward to using it more!

– Hollis

Blowing on the impeller to show wind speed (click to see full-size image)

Update: 24 December 2009

Hi folks! Here’s a quick pre-Christmas update to let you know that I’ve been carrying the Kestrel to the tops of lots of mountains lately, and it continues to work really well.

I used it this week while ice climbing at Azure Mountain, NY, and also while hiking in the High Peaks with some friends–we climbed Cascade and Porter Mountains, which are the 36th and 38th highest mountains in New York.

It’s really winter here, which gives me the opportunity to comment on the Kestrel’s cold-weather performance. It does really well! We were really cold on Cascade, to the point where we started getting nervous about frostbite inside our gloves. Sure enough, the Kestrel showed a wind chill of -19 Fahrenheit (based on air temperature of about 5 F and wind speed of about 19 knots). It’s cold out!

-19 F on Cascade! (click for full size)

I was testing new mountaineering boots on Azure, and the Kestrel helped me determine that they were comfortable for belaying as long as the temperature stayed above about 5 F. When it got colder, though, I felt like I was growing toe-cicles!

I also carried the Kestrel to the tops of Lyon Mountain, Catamount, Mt Arab, and Mt Morris within the last few weeks. The large buttons on the Kestrel work well even while wearing gloves, which is wonderful!

The Kestrel also helped me diagnose a furnace malfunction, since it let me measure air temperature throughout my house and find the places where it was a little bit warmer. The thermocouple is very sensitive and quick to update, and it picks up pretty small variations in air temperature.

The only regret I have so far is that I wish N-K would include the computer interface with the Kestrel, or at least make it less expensive. There have been many times when I would have liked to compare the atmospheric data visually, and it’s hard to do without the computer interface.

Otherwise, I’m truly impressed by the Kestrel meter. I gladly bring it on every trip these days, and it’s giving me some really useful information about how my insulation system performs in different conditions.

More information soon, and I hope you all enjoy your December holidays!

– Hollis

Hollis on Cascade Mountain, 19 December 2009 (click for full size)