November 30, 2010

Deciding on Weather Instruments

The Davis Vantage Pro is an example of a high quality instrument package at a reasonable price

One of the most frequent questions I get, particularly during the holiday season, is about purchasing weather instruments. Which are the good ones? How much should one pay?

The good news is that high quality weather instruments are available in all price ranges, with some amateur gear approaching professional quality. And the electronics of some are quite amazing.

There is no more entertaining and satisfying hobby than taking your own weather observations. You get tuned into the changing environment in a very different way than passively watching the TV weather segment. And it is for YOUR location, which is probably very different than Seattle-Tacoma Airport, Portland, or some other major city airport.

Did you know that the founding fathers--like Jefferson and Washington--were weather enthusiasts that took weather observations much of their lives? And look where it got them!George Washington took daily weather observations until the week before he died.

So lets say you are on a tight budget. Many of us are these days. No problem. My suggestion: get a really good rain gauge. A beautiful model used by a group of cooperative observers (CoCoRahs) is available for $25. plus shipping from accurate and durable. Or you could get a truly excellent cloud chart like this one for $5-10 dollars:Such charts are available from many online vendors and some local outlets and will help you learn the cloud types. And those inexpensive digital thermometers that are sold in many stores (e.g., Bartell's, Fred Meyer,Home Depot, etc.) for roughly $10-20 are really fairly accurate. Many are wireless .. making installation easy. I have three of them!
Remember, temperature sensors should be out of the rain on the northern side of your home or apartment. Temperature is ALWAYS measured in the shade. Rain gauges should be in the open AWAY from roofs and trees.

But what if you want to get a full-fledged weather station and even want to interface it to your computer and have the data available on the web? Systems that will give you wind speed and direction, temperature, humidity, pressure and rainfall. No can have this at a steeper, but still reasonable price.

Lets start with the best. If you want to invest in the very best, instrumentation that is near professional in quality and that will last for years, you can't go wrong with the Davis Vantage Pro series (see top picture). My colleagues and I have been impressed with the quality of this instrumentation and its ability to interface to computers and the internet. The cost? $350-$700 depending whether you get wireless or wired and the instrumentation options. If you have the cash get an aspirated (internal fan) temperature shelter/enclosure.

Davis has just come out with a cheaper (though not as good) line..Davis Vantage Vue. And then there is cheaper, less accurate gear from firms like Oregon Scientific, La Crosse, and Ambient. Sometimes these weather stations are even available in COSTCO for under $100! These would be good starter sets and perfectly serviceable if you don't care if your pressure is off by a few mb and the wind speed is in error by a few knots. They may also lack the interfaces to connect to your computer.

This complete weather station only costs $60 from Ambient Weather!

A company, Ambient Weather, sells many of these units (as does Amazon), and has a nice website, with comparisons of the quality of the various units:

Nautical supply houses also sell weather instruments, but prices tend to be high.

And, of course, any of these weather stations would be enhanced with a certain book on northwest Weather, noted in the upper right of this blog, but it would be inappropriate for me to discuss that any further!

Finally, I should note that the availability of these great weather systems and software allowing access via personal computers has been a revolution for my field. THOUSANDS of such stations are online in real time and can be viewed at sites such as The biggest problem is poor siting...many people are not careful where they place the sensors, resulting in bad data.

PS: We are going to have absolutely boring, benign weather during the next five days. Not much precipitation. No lowland snow. Little wind. No heavy rain...even some sun! Dull! Good time to install a weather station!


  1. Awesome. I have the Davis Vantage Pro 2 for over two years now. It's such an accurate station. One thing that should be noted is that Davis Instruments has amazing customer service. If your station needs any kind of service, they'll definately help out. I doubt you'd get that from Ambient, Oregon Scientific. Your book rocks too!

  2. I've had a Vantage Pro for several years now and have really enjoyed it. Linked to my computer and posts to Weather Underground. Had some corrosion issues with the original circuit board, but Davis has made modifications over the years and replaced mine for a very reasonable charge. A bit pricey, but an extremely good product.

  3. I have been operating a Vantage Pro II on Copalis Beach for two years. It is a very accurate instrument but be prepared for some maintenance if you are in a wet coastal environment.

    The salt air takes a toll, particularly on the temperature/humidity sensor. I have replaced mine three times in two years. The first was covered under warranty. After that the cost is about $70 for a refurbished unit in exchange for the failed one. It looks like a year is about all I can get out of a unit and I need to replace mine again.

    One direction sector of the weather vane failed while under warranty and the anemometer failed a few months ago. A refurbished replacement was about $100.

    Davis has been responsive but only to phone calls. They may not respond to emails if the problem is complex.

    Paul Middents
    Citizen Weather Observer Program (CWOP) DW 1622

  4. I too have a Davis Weather station – predates the Vantage-Pro . It has been working flawlessly for over 15 years. While taking weather data is, as Cliff says, a fun project it also can have very proactive applications.

    My company makes software that can interface with weather data to control things based upon weather conditions. For example, to retract motorized awnings in high winds, or not watering the garden if there has been enough rain in the last few days. I know of a user who adjusts HVAC settings depending upon outside temperature – accepting a higher cooling setpoint when very hot or a lower heat setpoint when very cold. He saw good energy savings doing this.

    Take a look at

  5. Davis also has a new recording device that allows you to download all your information to their website and view all the data online WITHOUT the use of a PC, 24/7.

    I work with Green River Community College and I have set up stations at Harvey Airfield in Snohomish county, Crest airpark in Covington and at my own home in Normandy park. Each of them Davis vantage pro plus 2. The Harvey airfield setup isnt great.

    IF you want to see what the data looks like online you can see the GRCC station online here:
    and my house (using the great davis website) here:

  6. If you want to get your weather station setup as good as possible here is the Citizen Weather Observer Program parameters here:

    It talks about sensor setting, what to do and what not to do and how to maximize your location.
    Good info.

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  8. Do most of these weather stations discussed come with an atomic clock AND the ability to record and save high and low temps for the basic midnight-11:59 p.m. time period each day?

  9. @ Michael... tried to check out your links but access was denied.

  10. I have the Honeywell TE923W weather station and while the USB interface is nice, I've had to replace the rain sensor twice and for the past year I have not had rain data to complement my other data. It just freaks out at random and records 8 inches of rain on a sunny day. I suspect some sort of interference, but I can't pinpoint it. I also suspect it might be the head unit rather than the rain collector device, but I can't afford the replacement at this time. Like with may things, you do get what you pay for.

    My father has the Vantage Pro 2 and he has had no problem with it in semi-coastal weather on the Columbia River on Puget Island.

    Both of us are Personal Weather Stations.

  11. I've looked everywhere for a good quality, analog min/max thermometer without mercury.

    Anyone have any suggestions?

  12. I'd like just a good barometer. Any suggestions?

  13. Great info Cliff, I just received a grant to purchase and install a weather station, the timing of your post is perfect! Could you discuss in a future post the siting requirements to provide accurate data that will be valuable to the NWS, the UW and other researchers.
    Our site is up the Middle Fork of the Snoqualmie where we get weather extremes that don't often get noticed or recorded even downriver in North Bend.
    Collecting and reporting accurate data is our goal.
    Thanks again

  14. Great info, Cliff!

    But you say "The biggest problem is poor siting...many people are not careful where they place the sensors, resulting in bad data."

    Are you going to have a column soon on how to site these stations beyond putting rain gauges out in the open and sensors on the north side in the shade?

    We have two of those digital temperature sensors, but the sensing units are attached to the side of the house. I often wonder whether this is resulting from inaccurate readings either from heat escaping from the house (even though it's well insulated) or from some other cause.

  15. Not weather instrument related, but very interesting climate information.

    Little known temperature records set in November at Sea-Tac:

    Largest difference between highest and lowest temperature in a single calendar month - 60 degrees (high 74, low 14). Old record: 57 degrees set in May 1963 and February 1950.

    Largest difference between highest and lowest temperature in any 21-day (three week) period, regardless of month - 60 degrees (high 74, low 14). Old record: 57 degrees set from May 3-21, 1963 and May 22-June 9, 1955. Note that the 58-degree difference from November 3-23, 2010 broke the record before that was eclipsed by the 60-degree difference from November 3-24.

    Largest difference between high temperatures in the same calendar month - 49 degrees (high 74 on November 3, high 25 on November 23). Old record: 45 degrees set in September 1988.

    Largest difference between high temperatures in any 21-day (three week period) - 49 degrees (high 74 on November 3, high 25 on November 23). Old record: 44 degrees set from May 30-June 9, 1955.

  16. Seeking recommendation for Anemometer
    I am looking for an anemometer to mount on the roof of my Phinney Ridge house. Analog or digital-doesnt matter-would be nice to be able to record maximum wind gusts..Have looked around..but nothing has jumped out as the best. Your assistance greatly appreciated

  17. I bought a analog wind gauge some time ago. Very entertaining in wind storms as the needle bounces around and the LED's show the wind direction. Also very expensive. Right now I have my eye on a Barograph at an antique shop that needs some work.

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  19. OK Cliff, the "next five days" of no snow was noted.
    Let's all prepare for the potential of snow in one week's time!

  20. Thanks for all you wx equipment tips...during such boring weather!

  21. Christopher, if you want to do it with Big Boy rules, go to NOAA and download NDSPD 10-13, a pamphlet which give the rules to set up a station with proper observer's perameters.

    NOAA has a bunch of observer programs, but I dropped out when they told me my Air Force schooling wasn't good enough any more. If you want to get outdoors at the same time every morning, you can join CoCoRaHS and just do temperature/humidity observation.

    Weather Underground is a bit more relaxed, but they don't check up on station installations like NOAA would (tho, NOAA needs to check up on some of their own, like Toledo).

  22. Thanks Cliff! I have a La Cross but I'm not really happy with it....I received it as a gift about 5+ years ago. I think I'll invest in a Davis!

  23. In response to Wx Enthusiast's post regarding "Largest difference between highest and lowest temperature in a single calendar month" at SeaTac.
    Out here in the hinterlands / foothills we experienced an even greater swing. Our high temp for this past November was 79 degrees and our low was 7 degrees. A 72 degree difference.
    Sure glad that did not happen overnight!

  24. I went to a weather-observer training at NOAA Sand Point. They said a rain gauge should be located as far from the base of tall objects as the height of those objects. Seems to me that rules out most of Seattle.

  25. Here is a great example of the Davis weather page. With the Weatherlink IP for Davis weather stations you can see your own personal station anywhere you can see the internet, like your smart phone!

    It will still setup with weather underground also.

    That Rain gauge that cliff shows here is great too, I use one to calibrate my Davis station. Plus you can take the top of to measure snowfall/melt it down to liquid.

  26. Cliff -- your link above the rain gauge only gives the photo. The link can be cut and pasted fine, but if clicked on it doesn't link correctly, at least for me.

  27. This is unfortunatey late in posting, but I need to point out one important thing about wireless indoor/outdoor thermometers: if you have low-E window coatings, they may not work at all! I had an older set from Radioshack that did work through my Low-E windows (and which I would still be using, except that the remote sensors were destroyed, one by a windstom and the other by a woodpecker) but the Fred Meyer sort do not have sufficient signal strength to cut through the window coating.

    This leaves me with a single wire-type Indow/Outdoor Max/Min thermometer, placed in the shadiest point on the north side of the house, and no good way of monitoring hig temps on the south and southwest exposures- a bigger prolem for a gardener than a weather watcher, I suppose.


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