The issues must be deep in the sim
I also noticed clearing the weather seems to get things back on track.
Totally agree with you had the same issue as you. Even REX not working anymore… If that would be even the biggest problem I would be happy…
I have found a way to reproduce this bug every time. Over the ocean heading towards YBBN with real time and weather, OAT matches real world data:
A few minutes later the plane jolts suddenly and OAT jumps to the YBBN ground OAT.
Really hope this can get fixed.
EDIT: I kept on flying inland on the same heading and at 64nm away from YBBN the temps flipped back to match real world data.
REX has a different issue actually. Its like the temps are one level behind from what the real world reports, which matches your screenshot and what I found. Look at the winds/temp aloft forecast in your screenshot. At 10000ft the OAT should be +6C and at 18000 it should be -6C. You are close to 18000ft and your SAT(OAT) is +6C. If you were to take an OAT reading at 24000ft I bet you it would have been -6C (the reading its supposed to be at 18000ft). So in summary, REX uses the previous reported flight level temps; 2500ft instead of 5000ft, 5000ft instead of 10000ft etc.
It looks more and more like this is an unwanted interaction between the surface real time METARS and the MeteoBlue model which provides the upper level weather.
Did you happen to notice if the wind direction and velocity changed to match the YBBN METAR? When I have seen the temperature bug manifest, there is always an accompanying wind shift.
Flying over land, it would be difficult to determine which airport METAR is interfering, but approaching a relatively isolated METAR-reporting airport from over the ocean as you noted with YBBN might be a good way to test this.
I am going to try a flight from MMPR (Puerto Vallarta) and head northwest to overfly MMSL (Cabo San Lucas) That route is over water almost all the way, and MMSL and MMSD are the only two airports on the tip of Baja California that report METARS.
Yes, the wind did change to match the field winds. I didn’t even realise that, as I was just focussed on temps. You can actually see in my screenshots the wind went from 274/62 to 209/4. And I just turned around to fly towards YBBN and when the weather flipped the winds and temps matched the nearest station of YAMB which is 0/0. So at 24000ft I currently have no wind 
Same as my findings, your temps and winds almost matches the surrounding field weather stations EHTE and EHLE and not the temps/winds at the actual flight level.
maybe it has something to do with the feet to metric conversions? lol what do i know… it was great when i spent 50 dollars to buy this game… had a blast to fly around and to learn new things… now it seems 50 dollars broken… this starts to annoy me even more since atc and cockpit elevations is mismatch… so i had to offset 600 feet for every ATC request… no difference on fuel consumption when flying low altitude 5k and below with 10k… you get few reduction consumption… on 30k feet youre just bleeding fuel…
It seems pretty conclusive that the source of the problem is surface METAR weather “bleeding over” into the upper-level weather. In the past, the sim has transitioned from model weather to METAR winds and temps at about 1500 feet AGL when approaching an airport. Now, there is an acknowledged bug with altimeter readings in SU5 that might have something to do with this problem BUT - the problem first started several days before SU5 was released, so it is kind of a mystery.
I am going to try my test flight to Baja California in any case, just to see if I see the same problem the rest of you are reporting.
Very bad…
It makes engine temp. up to 1000 degrees.(A320NX)
The climbing performance be effected too.
If the physics were right, shouldn’t the cloud be forming as well within these temps? How come there are still clouds? and rain?
I hope they can fix the temperature issue soon! This sim is useless with this issue! And once they fix it, I may be happy if they leave the sim alone! Don’t want to go through a few weeks of not playing the game after every Sim Update! I understand this is hard work but as a consultant/company manager, I can’t understand how a big company like MS/Asobo can get away with so many major errors/bug! These errors are not minor, they are the core of a flight simulator!
You on Asobo star，not Earth 
Don`t use Earth physics.
They should hire people from KSP to work the physics then… never underestimate the Kerbals!
RIght now it is broken near ground, then is getting kinda normal above ~10000ft. Then it breaks again during crz.
I don’t understand that this does not have a higher priority for Asobo. Unless you fly low and slow, the sim is unusable right now.
seems everything now is working… fingers crossed i hope this lasts…
edit: my bad… now its not working again… guess i just have to use preset then…
why are asbo draging there feet, we should have had some sort of fix by now and or acknowledgement
