Idea

Seconding this with another use case: I need to to calculate buoyancy in aerostats. With dewpoint alone we could calculate relative humidity. I wonder, is this simvar missing because the data isn't present? I admittedly don't know what all would be dependent upon it to know if that's a silly question.

We'd like to get this as well please.

Will be extremely useful when implemented!

In case it is more or less impossible to get that information from the sim, I wonder if there might exist some (suitable licensed) library (in C or C++, so that it could be incorporated into WASM) that could be used to "guesstimate" relative humidity based on temperature, pressure, altitude, time of day, time of year, and geographical region? Like "in Winter, the air over continental Canada is very dry" or "the air over the coast is typically quite humid in summer", or "when rain is falling, and you are inside the rain, the relative humidity is typically also quite large".

This might have been easier in previous simulators like FSX/P3D, when you could query the Weather and get a Metar report, which is the only way you could get the Dew Point from the sim, by decoding the Metar string so, all you needed was either write your own Metar-decoding routines, or use some existing library ( there are plenty to choose from, usually free ).

However, since all the Weather API has been deprecated in MSFS, this approach is no longer feasible, so there must be some other way to obtain that info, an adding a couple of Enviromental Simvars seems to be the most obvious choice.

However, considering the sim now has an in-game option to read the actual Metar available to users, I wonder why the Simconnect API is still deprecated: couldn't be just reinstated (at least the REQUEST API calls), and pass to the application the same data users can see when choosing the Metar option ?

I believe I hard somewhere that this will be coming in SU10+, can anyone confirm this?

Bump. Would like to make AI contrail lifetime dependent on humidity etc.

Would also be beneficial for scenerymakers to guesstimate visibility for things like approach light activation.

A workaround for this would be requesting METAR of the current position/airport and do it according to that however this is obviously a workaround and would not yield correct results all the time.