Outside temp sensor accuracy

[TaxmanHog]

My favorite PSD technician from the days when I was interested in PowerStroke issues.

Sponsored

 

[Jim Lewis]

According to the NWS, (official) temperature sensors should be mounted between 4’ 1" and 6’ 7" above the ground. The height of wind sensors should be 30 feet above the surface (Bing quote).

See page 7 of pd01013002curr.pdf (noaa.gov) (link should take you directly there). You're supposed to be 100 ft from any extensive concrete or paved surface. Also, not near water or snow, etc.

I've seen abrupt changes in my truck sensor reading from driving on an open, entirely unshaded flat area in the middle of a concrete 4-lane highway to turning off onto a tree-lined residential area with grassy shaded lawns. The amount of variability in the real outdoor temperature is all over the map, so I'd say the truck sensor does a decent job of representing that.

When I start my truck in the garage, its sensor reading is usually within a degree or two of what my thermistor-based La Crosse weather station remote reports. That's a pretty stable environment with ~no wind, no sun, only mild convection, and probably mostly radiant heat. You have none of that when you're out driving (or even just sitting outside). And even within the garage, there are several degrees of temperature variability. The concrete floor under the truck measured with an infrared thermal gun is a few degrees cooler, at least, than the air temperature ~3 feet off the floor next to the truck (the location of the La Crosse remote).

I'd say worrying about the exact temperature where you are is not something you're really going to be able to define because the real temperature is so variable - literally, all over the map.

 

[Zprime29]

It's an ultimate nitpick, I won't deny that. Is there an "ice/freeze" warning when the temp gets low? My Legacy would put up a snowflake light when the outside temp dropped to 37. Would be nice to know if the reading biases high in that situation, wouldn't it?

 

[GoodSam]

sensor data must be reset by either driving the vehicle at speeds consistently about 20 MPH for at least 5 minutes to update the filtered data

Yep, back on the road for a few minutes and the Ambient Air sensor started walking back up from 58F to the 80F outside temperature.
But why did it get stuck down at 58F @Ford Motor Company ?
BTW, the a/c can only be set down to 60F or LOW as the next point down.

Sponsored