Find the best REX Atmos settings for realistic haze, cloud shading and colour in Microsoft Flight Simulator, plus calibration and FPS advice.
The best REX Atmos settings for Microsoft Flight Simulator use a restrained, near-default profile: neutral colour balance, low-to-moderate haze, Rayleigh scattering close to default, slightly reduced cloud brightness and only a small increase in cloud shading. Keep Live Weather in control of conditions, then adjust for visibility, display and time of day.
There is no universal set of slider numbers. Labels and ranges may differ between REX Atmos releases, particularly REX Atmos for MSFS 2020 and Atmos CORE for MSFS 2024. We recommend working relative to each control's reset position rather than copying raw values from another release.
Recommended REX Atmos settings
A realistic baseline keeps the colour controls neutral and limits each atmospheric adjustment to roughly 5–10% of the slider's total travel from its default position.
| Control | Recommended starting point | What to watch for |
|---|---|---|
| Colour balance and saturation | Neutral or default | Correct an obvious display tint only; added saturation quickly makes blue skies and sunsets artificial. |
| Rayleigh scattering | Default, or a very small increase | Too much produces an intensely blue sky or a coloured horizon band. |
| Haze or aerosol density | Default to moderate | Increase it for humid or polluted air and reduce it slightly for dry, high-altitude conditions. Avoid zero haze. |
| Sky brightness | Default, with a small reduction if highlights clip | Judge this using midday light before changing it for sunrise or sunset. |
| Cloud brightness | Slightly below default in bright daylight | Reduce it only until cloud detail returns; excessive reduction makes overcast layers grey and lifeless. |
| Cloud shading or contrast | A small increase from default | Back it off if cloud bases become black or sharply outlined. |
This is a natural-looking starting profile, not a dramatic screenshot preset. Our overview of Atmos CORE's haze, cloud and scattering controls explains what the main atmospheric adjustments change.
Which profile suits each weather condition?
The right profile depends more on air mass and lighting than on aircraft or location.
- Clear, dry VFR: keep scattering near default, reduce haze by one small step and leave colour balance neutral. Completely removing haze creates an unrealistic cut-out horizon.
- Humid or urban conditions: add moderate haze while retaining neutral colour. Do not compensate for reduced clarity by increasing saturation.
- Overcast or IFR: return cloud brightness closer to default and use gentle shading. Let the weather engine determine poor visibility rather than manufacturing it entirely with an appearance slider.
- Dawn and dusk: move brightness and colour controls towards default. Microsoft Flight Simulator already applies warm, low-angle light, so an additional orange or red bias is usually excessive.
- Cinematic screenshots: stronger cloud shading and reduced haze can add drama, but save that separately from a normal flying profile because it can obscure detail and visual references.
How do you calibrate REX Atmos properly?
The reliable method is to tune Atmos against a repeatable weather preset before judging it under changing Live Weather.
- Confirm the correct setup. Use the Atmos release intended for your simulator, establish its connection and select the weather mode required by that release. Our REX Atmos installation and connection checklist covers these prerequisites and conflicting weather utilities.
- Create a repeatable test. Temporarily choose a built-in clear or partly cloudy preset, then use the same airport, time and camera position for every comparison. Live Weather can change while settings are being adjusted.
- Set MSFS graphics first. Choose a sustainable Volumetric Clouds quality, render scale and exposure setup before touching Atmos. Use our recommended MSFS graphics settings to establish that baseline.
- Reset Atmos. Return all appearance controls to their defaults, then change one control at a time. Start with haze and scattering, continue with brightness, and adjust cloud shading last.
- Check several conditions. Test clear midday weather, an overcast layer and low-angle sunlight. A profile that only looks correct during a vivid sunset is not balanced.
- Recheck Live Weather. Restore Live Weather and distinguish genuine weather-driven visibility from the Atmos appearance profile. If supported by your release, save separate natural, hazy and screenshot profiles.
Calibrate SDR and HDR displays separately. A profile made to recover highlights on an HDR screen can look dark and oversaturated in SDR, while display tone mapping may be responsible for clipping that no Atmos setting can fully correct.
Why do copied REX Atmos settings look wrong?
Copied settings usually fail because the other user has a different Atmos release, weather state, display mode or MSFS cloud setting.
- Bleached cloud tops: lower cloud brightness by one small step, then check HDR calibration and simulator exposure before reducing it again.
- Ink-black cloud bases: reduce cloud shading or contrast. Raising brightness to compensate often destroys the highlights as well.
- Electric-blue sky: return Rayleigh scattering, saturation and colour balance towards default.
- Milky horizon everywhere: reduce haze or aerosol density gradually, but first confirm that Live Weather is not reporting genuinely restricted visibility.
- No visible response: check the simulator connection, required weather mode and any second weather utility. Do not run two applications that are trying to control the same conditions.
Do REX Atmos settings reduce FPS?
Colour, scattering and modest haze adjustments are rarely the main performance cost; dense volumetric clouds, precipitation, reflections and changing weather coverage have a much larger effect.
If frame rate falls in poor weather, lower the simulator's Volumetric Clouds setting before stripping useful atmospheric effects from Atmos. Our live-weather performance adjustments identify the settings that usually recover the most performance without flattening the entire scene.