The problem is that the MB model probably doesn’t have enough fine-detailed resolution to predict how far a coastal marine layer is going to penetrate inland, and when. Though I now live in the northeast, I grew up in San Diego, and well remember that it was not uncommon for Lindbergh Field to have a solid low overcast in the morning, while 10 miles inland at Gillespie Field, it might be bright and sunny. Other days if the onshore flow was a bit stronger, the cloud deck might reach all the to way to KSEE.
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@HalberQuacky Jim, that’s the best answer I’ve had about this issue. I really appreciate this because this behavior has been driving me crazy. Testing other airports around the country and the world has revealed a decent amount of accuracy, without being there in person, but I haven’t been able to wrap my head around why it doesn’t seem to be the case in my area. Having lived in San Diego, you understand exactly what I am talking about. I really appreciate it. Just having an answer I can understand makes me feel a lot better. Now, if you could offer some insight as to weather improving in game ATIS reporting is on the back burner by the devs, I would feel even better because without decent ATIS flying VFR is really challenging in some parts of the world as you know. Obviously, I could just change the weather on the fly but that’s not really the point.
Again, thank you. You brought me a sense of relief just understanding why this could be behaving this way.
Even the models used by NWS offices can have issues with the TAF forecasts for airports, when dealing with what amounts to a microclimate.
My local airport KELM, is often solidly fogged in between approximately 0400 and 1000 local at this season of the year. Yet, it is not uncommon for it to be clear just 3 or 4 miles east or west of the field. The airport is in a valley, and it is at the lowest point in the valley, so at night when the air cools, the coldest air pools right where the airport sits.
The forecast model that the NWS uses to generate the initial terminal forecasts for local airports does not have enough resolution to pick up on the effect the slight elevation difference has on whether fog forms or not.
Fortunately, airport TAF forecasts are always hand-edited by local NWS forecast offices who know the area well, and are aware of local microclimate effects like the “fog zone” at KELM.
Sometimes though, the human forecasters at the NWS still can’t predict aviation weather with a great deal of certainty, even with their eyes directly on the weather and with real-time observations available.
The following is the actual aviation weather forecaster’s discussion from the LAX NWS office for airports in the LA basin from this morning, 21 OCT:
“At 1754Z, at KLAX the marine layer was around 1700 feet deep. The top of the marine inversion was around 4800 feet with a temperatures near 23 degrees Celsius. High confidence with desert TAFs and KPRB for VFR Conds. Moderate confidence in the coastal/valley TAFs
VFR conditions have returned to valley locations while many coastal sections remain mired in marine clouds. Some coastal TAF sites will not clear this afternoon, others will clear later this afternoon Overall,VFR conditions will remain through the afternoon before MVFR conditions become dominant early this evening with the widespread marine clouds arriving tonight. A couple of locations may see brief IFR conditions overnight due to a thick cloud layer, and the marine layer depth is expected to deepen to around 2500 feet Thursday morning.
KLAX…There is a 30 percent chance of marine clouds arriving plus or minus two hours from the forecasted time. There is a 30 percent chance of east winds reaching 8 knots Thursday morning.
KBUR…There is a 30 percent chance of marine clouds arriving plus or minus two hours from the forecasted time”.
So - as you can see, even the official NWS forecasters who are right therecan have a difficult time pinpointing whether airports like KBUR will cloud over or not, and exactly what time the clouds might arrive or leave.
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@HalberQuacky I appreciate you. Thanks for taking the time to explain this. I know I’m one user and in the grand scheme of things rather unimportant. You took a great deal of time to explain this and I really appreciate it. I’m not new to flight sims. I’ve owned every version of MS Flight Sims since the beginning (yeah, I’m old) and really enjoy the details. You’re very kind taking the time to help me understand this.
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And wouldn’t you know… I did a TBM flight two hours ago from KLAS to Montgomery Field in San Diego, landing about 2:00 PM local time. It was unlimited visibility over the desert to the east, but soon as I started descending over the Cuyamaca mountains, I could see a solid cloud deck along the coast, extending about 5 miles inland. KMYF ended up having a broken layer at 600 feet AGL. Actual METAR was 1800 feet scattered at that time, but it was overcast earlier in the day.
@HalberQuacky also wouldn’t you know … this morning the low clouds and fog have socked in KVNY as it has all this week again but this time I decided to check meteoblue and I could see that those conditions were represented on their maps. So, sure enough, in game I spawned at my usual parking spot at VNY and viola the low visibility and low clouds were all there. Just like you said! Thanks again for explaining it to me.
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In addition to the weather bugs… The live weather doesnt update the atis correctly. The clouds reported by the ATIS are almost always the same no matter.
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@TonyCowboysFan Much better depictions over KVNY today. Probably helps that we are getting more weather then just the marine layer. Summer is kind of a boring time in SoCal for weather. It will be interesting to see how the weather system works out as we get our winter weather.
Don’t forget to tune into the Dev Q&A next week. The #1 topic is “Live Weather” in the sim 
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I noticed that too. That should be added to that Q&A topic.
Simply put - Asobo needs to develop some sort of hybrid MeteoBlue Forecast/METAR blend. The fact is, when flying online we need things like winds, altimeter, and visibility to match. I’m more flexible when I’m at cruise, but this needs to be a HOT topic for them a the Q&A. It’s ok to admit issues… just ADMIT that it is in fact something that needs considerable improvement.
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They gave us the answer in the Q&A: they’re already using a Meteoblue/METAR blend. 
What you’re seeing on the world map is always Meteoblue data while each airport gets METARs for the winds (if available, I guess). That’s why there can be a small difference.
There has, however, been a bug on the server side leading to some METAR data being up to 24 hours old – exactly what some of you reported. It’s already fixed and should work even without the update. If not, Update 5 will fix it.
I don’t know if they fixed the high temperature over mountainous terrain yet, we’ll have to wait for the patch notes.
If there are further issues, they should be much more easily discernable now without the wrong METAR data input on top messing everything up. Good job, community!
EDIT: Of course, there’s still a lot of work to do, like correct cloud coverage given in ATIS reports and visibility overall - but if the features so far are bug-free it’s already great.
as I tested after Q&A… metars are still incorrect, nothing changed, still live weather is a joke, and Lighting everywhere from few clouds…
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They did say it could take a while.
Checked today and the weather is still at least 6 hours delayed. I did like what I heard about METAR data ONLY for the airports and it updating every 30 minutes. So, we SHOULD have accurate live weather at some point hopefully.
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When I checked 10h ago, weather was still off, right now US weather is looking good.
However, the greatest discrepancy has always occurred later during the day, so let’s wait a couple days and monitor.
I did a flight around Corse Area ( Bastia ) and live weather was absolutly accurate regarding clouds/wind/winds aloft/QNH/temp. I checked with meteoblue all the time. Clouds coverage seems perfect.
I’m sorry, but the new update is still not producing accurate weather.
When doing these tests, the best results are just looking out the door in my opinion. I can’t tell you what’s really happening in Chicago. Earlier today Zeta moved through Central Virginia. The skies were mostly clear around 1600 local time. There are some small clusters to the SW, but mostly clear in the area. I’ve attached an image showing MSFS patch weather, unrealweather, RL weather in central VA, and live radar. Asobo, make the METAR truly blend… you said in your twitch you wanted SPECIFICS. This is as specific as it gets!
I made a single test flight after the update and weather was much worse than before in terms of accuracy. Here’s my report:
Did they say they actually fixed METAR station reporting??? Just loaded up at KTHV with “LIVE WEATHER.” Pressure off by nearly .30 inches, LOL!
They did mention it might take a day or two to see the server-side fix, but I’ll believe it when I see it.
I do like how they confirmed that all airport weather (with weather reporting) should be using METAR data only. All the trolls who were saying that METAR’s can’t be trusted to provide information on what’s occurring at the airport must be thinking of new excuses for the “live” weather.
I haven’t had a chance yet today to check if it’s working any better.