Jump to content


  • REX 6 - Weather Force 2020

       (Overall rating from this review)
    ... Using Weather Force now seems natural and fits nicely into my flow to get airborne, it's as easy as: set up flight, start Weather Force, and fly! ...


    Rex Game Studios are a company synonymous with flight simulation weather. As far back as 2007 when Reed Stough and Tim Fuchs partnered to create REX, they realised Microsoft Flight Simulator severely lacked a realistic environmental system, with Tim's texturing skills and Reed's expertise with weather engines they forged a company still ahead of the game today. REX announced and released their latest product Weather Force within a month of the launch of Microsoft Flight Simulator.

    Why REX?

    In the development of MSFS, Asobo Studios partnered with Swiss company Meteoblue for weather generation. The Meteoblue engine is a forecast model using complex equations and predictions from gathered and historical data to generate what it expects the weather to be, but the prediction has a chance of being wrong, have you ever been thrown a curved ball by the TV forecast? I have.

    REX takes a different approach, Weather Force uses Meteorological Terminal Aviation Routine weather reports (METAR) to produce dynamic real-time weather. The METAR data is updated an advertised 6x an hour and downloaded directly from the National Oceanic and Atmospheric Administration (NOAA) server. The data used can provide accurate results within a 1/8th mile of a given point, usually the nearest airport.

    Where there is no weather station nearby, such as deserts and oceans, Weather Force utilises uniquely built algorithms to combine both METAR and Global Forecast System (GFS) weather prediction model data resulting in the best possible weather scenarios.

    Weather Force reads remarks (RMK) provided with live METAR reports to determine if storms are near the aerodrome. Thus, even if the automated METAR may indicate clear conditions, if remarks indicate storms nearby, storms will be generated near the reporting station as in real life.

    Dynamic Weather Presets

    To mix things up and add more interest, REX have designed Dynamic Weather Presets (DWP). "Dynamic" is key about their weather scenarios in that they are not static like the default weather presets inside Microsoft Flight Simulator. Weather Force scenarios dynamically change over time. A weather scenario will provide various elements of changing weather over the course of your flight.

    Examples provided below of included scenarios:

    • Fair weather day
    • Approaching cold front
    • Approaching warm front
    • Hot and humid summer day
    • Lake effect snows
    • Winter storm
    • Crisp winter day
    • Breezy
    • Spring showers
    • Blizzard
    • Thunderstorm
    • Rainy day
    • Bob Ross Happy clouds

    Favourite Airports

    In Weather Force you can easily track your 10 favourite airports, therefore, clearly identifying what the detailed weather is like at each. If you require a more detailed report, simply click on the ICAO and receive in-depth data about the airport weather conditions.


    Step 1 read the manual. Do not forget, this program interacts with servers on the internet so make sure Weather Force has inbound/outbound permission via your firewall software. The installer is simple click away. Ensure not to install in your MSFS directory, the installer will default to its own preferred directory so just accept the choices given.


    Temperature and pressure are switchable between the US system of Fahrenheit and inches to the European system Celsius and millibars. Weather injection can be set to real-time or if deselected revert to the Dynamic Weather Presets. In addition, they have added a smoothing mechanism to the engine to gradually smooth and transition the weather over time between updates.

    When loading a weather update, the program can be set to instantly update at selectable intervals or use a persistent weather load method where the weather will load smoothly over time. Time to transition between weather injections can also be set. Aerosol density can also be injected at the same time, basically, it is supposed to lower the visibility due to either particulates or water vapor in the air. Like other complex visual effects it is hard on Frames Per Second (FPS).

    The program is in a constant improvement mode, at the time of writing the latest technical update takes the program to version 1.2. In the settings screen the program can be set to manual or auto update, the auto update, however, still requires download of the new version and re-installation, you will need your serial key as it will ask for it again.

    In Use

    Navigating around the options is very intuitive, you either want to fly live weather or use a Dynamic Weather Preset. In order for MSFS to accept the weather you must first start the sim and set the weather to clear skies, after clicking the green Start Weather Synthesis button Weather Force just runs in the background and shouldn’t need any more attention. One slightly annoying feature to me is you must click through an alert window to start the synthesis, it would be nice to see this as a switchable option for experienced users to bypass. The program takes around 20 seconds to fetch and inject weather for the first time, thereafter at intervals set in the settings screen. I have experienced the odd glitch where after injecting the weather it doesn't show, only after moving the aircraft do the skies change. I believe this is a known bug at the time of writing. 

    Dynamic Weather Preset "Approaching Warm Front" after first injection

    "Approaching Warm Front" after 30 minutes of gradual transition

    If live or dynamic weather presets are not your preference today the "Search Weather" function can be used, if you are a previous user of REX weather products you will be familiar with this function. You can search by ICAO code or search by parameters. The main parameter is for "Type of weather" and include:

    • Rain
    • Snow
    • Haze or smoke
    • Thunderstorms
    • Fog
    • Towering clouds

    Other refinements for visibility, cloud base, and windspeed are offered too. Airports found by the program are listed in alphabetical order with the latest METAR attached which should match the parameters chosen. Once the location is chosen, the system then runs in live weather mode.


    Whilst the live weather display is superb and true to the METAR displayed, I have found on several occasions that the METARs being issued by Weather Force are woefully out of date/time. Presently, whilst writing this paragraph, the time in the METAR on REX is 260650Z, on checking on the web I am getting 261050Z, that's only 10 minutes ago. On enquiring, when it was a day out, it was due to the developers working on their server for the 1.2 update. Unfortunately, nearly every day since the METAR has been out and certainly not updating 6 times and hour as advertised. This is a problem in my view that REX must address.

    First Flight

    Getting everything set up at a local airport should make assessing its accuracy easier, my local airfield is EGHI and I live around 5 miles due east, so local enough that the weather outside should be similar.

    Here is the METAR with explanation.

    EGHI 181420Z 22012KT -DZ BKN014 14/14 Q1013

    The program also displays winds and temperatures aloft in nine bands from 2500 feet up to 44000 feet, it's worth noting the temperatures higher up along with the cloud to judge weather icing is likely.

    In the real world outside my window, the clouds are low and partially broken with occasional rain.

    Here is the result with REX Weather Force, visibility is reasonable although we have no distant reference to judge, the clouds are partially broken and there are odd drops of rain on the windshield and left window.



    This is the MSFS live depiction of the same event, as you can see, the MSFS calculated weather showed around 500 metres of visibility and overcast, you can tell by the brightness the sun is being completely blocked out.



    Unfortunately ATIS in the sim still appears to be broken, it only appears to communicate the sim time and weather from MSFS. Hopefully, in time, it will be able to decode METAR real time, this is not a problem with Weather Force but with the sim itself.

    So, Weather Force passes this test and my confidence in its veracity is growing.

    Building Hours

    I made many other targeted flights (see examples in the screenshot gallery) comparing the METAR with the generated weather and without exception the weather displayed fitted the METAR description with just a small amount of artistic licence, this must be expected and in my eyes fully acceptable.

    Being a long in the tooth GA pilot prone to cloud surfing, I like to get in amongst the clouds and explore the multitude of shapes and colours they exhibit. I know this behaviour is frowned on by some, but makes for some great screenshots! When testing in the Boeing 787 high above the top dense layer, the cloud coverage seems to go on for ever, it makes me smile when remembering the limited cover legacy sims used to deliver, what we now see is so realistic.

    Potential Risk Factor

    Asobo "clearly stated" that the SDK is not going to provide support for 3rd party weather engine development. REX have had to "reverse engineer" their product to inject the weather into MSFS. Personally, I feel this makes the product more prone to risk associated with the lack of "support" from Asobo with the potential for ongoing problems with future MSFS updates.


    REX have done a fabulous job without an Software Development Kit to work with. Weather Force is not without its own bugs but it is in active development, every new problem thrown up is addressed, the developers are active in their own Discord channel offering expert advice. They also have a support ticket system.  

    Overall, the program does a great job injecting weather into the sim, but I feel a need to keep an eye on the data it is using for live depiction as their servers are doing it an injustice.

    Weather Force is available from the REX Simulations store and other resellers, it is priced at US$21.95 and represents good value for money.

    Using Weather Force now seems natural and fits nicely into my flow to get airborne, it's as easy as: set up flight, start Weather Force, and fly!

    • Live weather decoded from METAR and other dynamic sources
    • Dynamic preset weather scenarios
    • Smooth transitions
    • Little effect on performance
    • Clean, intuitive interface
    • Sometimes METAR updates appear to be static and out of date
    • Starting the synthesis needs a fast track option for experienced users
    • Still has bugs
    • Overall Rating

    User Feedback

    Recommended Comments

    Please sign in to comment

    You will be able to leave a comment after signing in

    Sign In Now

  • Create New...