Topic: need help deciding for my weather station

[zzz]

This is my ambient ws-2902 station. I've had it for a year now, but i have my eyes on a Davis Vantage Vue. I don't know if my temperature readings are entirely accurate. they usually read too cold. Could it be the station or the place its mounted because i don't want to spend 600+ on a Vantage Vue if it wont be accurate for the temperature. Its around 10 feet above my roof.

[R.Sidetrack]

I hope this isn't an impertinent question, but how do you know that the temperature reading is not correct?

Just looking around at local PWS as shown on the Weatherunderground map, I see temperatures that vary from mine.  But a local conditions vary, who is to say which is "correct"?

I have 2 completely separate systems located about 800 ft apart, and they vary from each other. No doubt the sensors have some level of variance, but  local conditions vary -- even at 800 ft.

[zzz]

I guess that's true. There's a station one mile away from me right now and it says 75.4 mine right now says 73.9. Another by also says 75.4 so it kind of makes me think mine isn't accurate. But what do you think? Would i be good buying the vantage vue? And also there is times where mine matches exactly with the other stations nearby, usually at night.

[R.Sidetrack]

If the difference bothers you, look to see if your system allows you to 'calibrate' the  results.

  One option would be to just add 1.5 degrees to your system through a calibration adjustment. 


If you WANT to buy a new system,  go right ahead. 

But an alternative is to save your money until your existing system has a bigger problem that requires a purchase.

The primary reason I have two systems is that my house is more-or-less within a circle of trees at the top of a hill.  My other system is about 70ft lower elevation in a more exposed area (wind blows harder there). But I also like that as the parts of both systems are similar, I can move components around to explore if one part has a problem.  I think there is a lot to like in an Ecowitt system that has discrete parts, and I am not concerned about minor difference in readings.

[zzz]

 I probably might just wait for a bigger problem then. Thanks for your help 

[vinceskahan]

Buy a couple ecowitt inside t+h sensors for 30 bucks and you’ll see they are within 0.5 F in shade. Then check your station vs them at night after there’s no sun heating of your station.

I validated mine vs a few ds18b20 sensors and everything was within the sensor specs for accuracy

[blizzardof78]

Davis Vantage Vue is what I use. And I wouldn't be overly concerned with a minor difference in temperature. I would stay AWAY from any weather station manufactured outside of the US, like China. Go to eBay and search for the Davis Vantage Vue. Now and then you find one slightly used and marked down quite a bit. Also go to a web site called Scientific Sales and look there. And good luck!

[swright1957]

I have a ecowitt wittboy and the temp that this is showing is always a bit lower than the official weather apps as we are right near the beach, but I do have an outside temp and that is correct with the wittboy, so yes how do you know the temp is wrong?

[zzz]

Sometimes my temperature readings match exactly with the weather stations, but other times, they can be off by as much as 1-4 degrees compared to areas just 1-2 miles away. That’s why I’m not sure if my readings are accurate.

[blizzardof78]

Sometimes my temperature readings match exactly with the weather stations, but other times, they can be off by as much as 1-4 degrees compared to areas just 1-2 miles away. That’s why I’m not sure if my readings are accurate.

That's called "Micro Climate". Again, I wouldn't worry about that being an issue. For example, the stations 1 to 2 miles away, how much of a difference is there in elevation between your location and theirs?

[zzz]

elevation is about a foot different. i think it is just a micro climate. a couple hours ago, i set up a thermometer in my backyard about 5 feet high. the difference between the thermometer on the ground and the one on my roof is very small. the difference is around 0.0 to 0.3 degree difference. i would say my station is accurate.

[zzz]

this is my station vs the thermometer.

[weatherdoc]

I have a Davis VP2 and the temperatures and other parameters rarely match nearby stations - no telling which one is "right". Take a look at this map of surface temperatures in the Detroit metro area - which station temperature is right?

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[DoctorKnow]

That Osprey weather station is very good. The only thing that could be improved is the rain gauge calibration. It reads a little high. The temp and humidity are really accurate for highs, but at night, I think it might be a degree or two high. I took mine down recently, and one of the vents in the sun shield had a thick spiders web. That is likely why mine was off. I did not re install it though and went back with acurite.

[vinceskahan]

I have a Davis VP2 and the temperatures and other parameters rarely match nearby stations - no telling which one is "right". Take a look at this map of surface temperatures in the Detroit metro area - which station temperature is right?

They are likely all correct for their individual siting plus/minus oddities of the cases the sensors are in.   You'll see all kinds of variance between sites especially in daylight as each kind of gear might heat up its case as the sun hits it, or alternately hold onto the heat as it moves from direct sun.  Local winds can also have a lot of effect.

(example - a weatherflow tempest is slow to warm up, heats up a lot in calm weather, and holds that heat as it cools after it's not in direct sun late in the day.   I see temperature bouncing a little on my VP2 with DFARS when I get wind from the north off the cool Puget Sound)

The only way to check yours is to do so in calm overnight weather versus a reference sensor.  I did a bunch of tests of Ecowitt T+H sensors vs. some ds18b20 sensor rigs I built on breadboards and found them all within the plus/minus accuracy of the specs for the devices.

[weatherdoc]

@vinceskahan, my point by showing the map is just what you stated, that they are all "correct" and you really can't compare your station to others to check the accuracy of your own temperature. I would say if you're within a couple of degrees of the stations in your area then your sensor is fine. If your station was consistently off by maybe 5 degrees day and night, then maybe there is a sensor issue, but more likely it's microclimate and/or siting.

[wd40]

So many factors when it comes to measuring temperature.  That is why there are published standards for sensor placement, and enclosures.

For home units, distance from the ground has a two degree F  influence at my house which varies from day to night.  More so if not over dirt- or grass.   Direct sun vs shaded vs solar shield size, and type can all add the error.  You know what you have but do you know what the stations around  your house has?

As so many have posted before, find your best compromise.