diff --git a/indra/newview/llenvmanager.cpp b/indra/newview/llenvmanager.cpp
index 9f2a1a8afd..8f87410011 100755
--- a/indra/newview/llenvmanager.cpp
+++ b/indra/newview/llenvmanager.cpp
@@ -347,7 +347,11 @@ void LLEnvManagerNew::setUserPrefs(
 	const std::string& sky_preset,
 	const std::string& day_cycle_preset,
 	bool use_fixed_sky,
-	bool use_region_settings)
+	// <FS:Ansariel> Allow interpolation
+	//bool use_region_settings)
+	bool use_region_settings,
+	bool interpolate)
+	// </FS:Ansariel>
 {
 	// operate on members directly to avoid side effects
 	mUserPrefs.mWaterPresetName	= water_preset;
@@ -358,7 +362,10 @@ void LLEnvManagerNew::setUserPrefs(
 	mUserPrefs.mUseDayCycle			= !use_fixed_sky;
 
 	saveUserPrefs();
-	updateManagersFromPrefs(false);
+	// <FS:Ansariel> Allow interpolation
+	//updateManagersFromPrefs(false);
+	updateManagersFromPrefs(interpolate);
+	// </FS:Ansariel>
 }
 
 void LLEnvManagerNew::dumpUserPrefs()
@@ -509,9 +516,10 @@ void LLEnvManagerNew::onRegionSettingsResponse(const LLSD& content)
 		//bit of a hacky override since I've repurposed many of the settings and methods here -KC
 		//NOTE* It might not be a good idea to do this if under RLV_BHVR_SETENV -KC
 		else if (gSavedSettings.getBOOL("UseEnvironmentFromRegionAlways") 
-		 && !(rlv_handler_t::isEnabled() && gRlvHandler.hasBehaviour(RLV_BHVR_SETENV)))
+			&& !(rlv_handler_t::isEnabled() && gRlvHandler.hasBehaviour(RLV_BHVR_SETENV)))
 		{
-			setUseRegionSettings(true, mInterpNextChangeMessage);
+			// reset all environmental settings to track the region defaults, make this reset 'sticky' like the other sun settings.
+			setUserPrefs(getWaterPresetName(), getSkyPresetName(), getDayCycleName(), false, true, mInterpNextChangeMessage);
 		}
 	}
 
diff --git a/indra/newview/llenvmanager.h b/indra/newview/llenvmanager.h
index 850cebfd9a..0ee22cde8d 100755
--- a/indra/newview/llenvmanager.h
+++ b/indra/newview/llenvmanager.h
@@ -213,7 +213,11 @@ public:
 		const std::string& sky_preset,
 		const std::string& day_cycle_preset,
 		bool use_fixed_sky,
-		bool use_region_settings);
+		// <FS:Ansariel> Allow interpolation
+		//bool use_region_settings);
+		bool use_region_settings,
+		bool interpolate = false);
+		// </FS:Ansariel>
 
 	// debugging methods
 	void dumpUserPrefs();
diff --git a/indra/newview/llviewermenu.cpp b/indra/newview/llviewermenu.cpp
index 13352486e5..2d9f8dccf4 100755
--- a/indra/newview/llviewermenu.cpp
+++ b/indra/newview/llviewermenu.cpp
@@ -10045,7 +10045,7 @@ class LLWorldEnvSettings : public view_listener_t
 			envmgr.setUserPrefs(envmgr.getWaterPresetName(),
 					    envmgr.getSkyPresetName(),
 					    envmgr.getDayCycleName(),
-					    use_fixed_sky, use_region_settings);
+					    use_fixed_sky, use_region_settings, false);
 		}
 
 		return true;
diff --git a/indra/newview/quickprefs.cpp b/indra/newview/quickprefs.cpp
index 9e2070d3b9..775066c23b 100644
--- a/indra/newview/quickprefs.cpp
+++ b/indra/newview/quickprefs.cpp
@@ -553,7 +553,15 @@ void FloaterQuickPrefs::selectDayCyclePreset(const std::string& preset_name)
 
 void FloaterQuickPrefs::onChangeUseRegionWindlight()
 {
-	LLEnvManagerNew::instance().setUseRegionSettings(mUseRegionWindlight->get(), (gSavedSettings.getBOOL("FSInterpolateSky") || gSavedSettings.getBOOL("FSInterpolateWater")));
+	LLEnvManagerNew &envmgr = LLEnvManagerNew::instance();
+	// reset all environmental settings to track the region defaults, make this reset 'sticky' like the other sun settings.
+	bool use_fixed_sky = !mUseRegionWindlight->get();
+	bool use_region_settings = !use_fixed_sky;
+	envmgr.setUserPrefs(envmgr.getWaterPresetName(),
+				envmgr.getSkyPresetName(),
+				envmgr.getDayCycleName(),
+				use_fixed_sky, use_region_settings,
+				(gSavedSettings.getBOOL("FSInterpolateSky") || gSavedSettings.getBOOL("FSInterpolateWater")));
 }
 
 void FloaterQuickPrefs::onChangeWaterPreset()