diff --git a/src/EnergyPlus/OutAirNodeManager.cc b/src/EnergyPlus/OutAirNodeManager.cc
index 5840a91b879..c39f1cab51b 100644
--- a/src/EnergyPlus/OutAirNodeManager.cc
+++ b/src/EnergyPlus/OutAirNodeManager.cc
@@ -592,7 +592,8 @@ namespace OutAirNodeManager {
         }
 
         state.dataLoopNodes->Node(NodeNum).Temp = state.dataLoopNodes->Node(NodeNum).OutAirDryBulb;
-        if (state.dataLoopNodes->Node(NodeNum).IsLocalNode) {
+        if (state.dataLoopNodes->Node(NodeNum).IsLocalNode || state.dataLoopNodes->Node(NodeNum).EMSOverrideOutAirDryBulb ||
+            state.dataLoopNodes->Node(NodeNum).EMSOverrideOutAirWetBulb) {
             if (InitCall) {
                 if (state.dataLoopNodes->Node(NodeNum).OutAirWetBulb > state.dataLoopNodes->Node(NodeNum).OutAirDryBulb) {
                     state.dataLoopNodes->Node(NodeNum).OutAirWetBulb = state.dataLoopNodes->Node(NodeNum).OutAirDryBulb;
diff --git a/src/EnergyPlus/api/datatransfer.cc b/src/EnergyPlus/api/datatransfer.cc
index 5c663e414c9..999dc1032a4 100644
--- a/src/EnergyPlus/api/datatransfer.cc
+++ b/src/EnergyPlus/api/datatransfer.cc
@@ -55,6 +55,7 @@
 #include <EnergyPlus/DataEnvironment.hh>
 #include <EnergyPlus/DataGlobalConstants.hh>
 #include <EnergyPlus/DataHVACGlobals.hh>
+#include <EnergyPlus/DataLoopNode.hh>
 #include <EnergyPlus/DataRuntimeLanguage.hh>
 #include <EnergyPlus/DataStringGlobals.hh>
 #include <EnergyPlus/HeatBalFiniteDiffManager.hh>
@@ -456,6 +457,16 @@ int getActuatorHandle(EnergyPlusState state, const char *componentType, const ch
             }
             ++availActuator.handleCount;
 
+            // Mirror EMSManager::SetupNodeSetPointsAsActuators for Python plugin path (issue #8904)
+            if (typeUC == "OUTDOOR AIR SYSTEM NODE") {
+                for (int NodeNum = 1; NodeNum <= thisState->dataLoopNodes->NumOfNodes; ++NodeNum) {
+                    if (EnergyPlus::Util::makeUPPER(thisState->dataLoopNodes->NodeID(NodeNum)) == keyUC) {
+                        thisState->dataLoopNodes->Node(NodeNum).IsLocalNode = true;
+                        break;
+                    }
+                }
+            }
+
             return handle;
         }
     }
diff --git a/tst/EnergyPlus/unit/OutAirNodeManager.unit.cc b/tst/EnergyPlus/unit/OutAirNodeManager.unit.cc
index bd41e4bcc0b..ab7036f82fa 100644
--- a/tst/EnergyPlus/unit/OutAirNodeManager.unit.cc
+++ b/tst/EnergyPlus/unit/OutAirNodeManager.unit.cc
@@ -104,3 +104,53 @@ TEST_F(EnergyPlusFixture, OutAirNodeManager_OATdbTwbOverrideTest)
     EXPECT_NEAR(0.007253013, state->dataLoopNodes->Node(2).HumRat, 0.000001);
     EXPECT_NEAR(0.006543816, state->dataLoopNodes->Node(3).HumRat, 0.000001);
 }
+
+// Reproduces GitHub issue #8904: EMS wetbulb override on OA node without
+// IsLocalNode=true does not recalculate HumRat.
+TEST_F(EnergyPlusFixture, OutAirNodeManager_EMSWetbulbOverride_NoIsLocalNode)
+{
+    state->dataOutAirNodeMgr->NumOutsideAirNodes = 2;
+    state->dataOutAirNodeMgr->OutsideAirNodeList.allocate(2);
+    state->dataLoopNodes->Node.allocate(2);
+
+    state->dataEnvrn->OutDryBulbTemp = 25.0;
+    state->dataEnvrn->OutWetBulbTemp = 15.0;
+    state->dataEnvrn->WindSpeed = 2.0;
+    state->dataEnvrn->WindDir = 0.0;
+    state->dataEnvrn->OutBaroPress = 101325;
+    state->dataEnvrn->OutHumRat =
+        Psychrometrics::PsyWFnTdbTwbPb(*state, state->dataEnvrn->OutDryBulbTemp, state->dataEnvrn->OutWetBulbTemp, state->dataEnvrn->OutBaroPress);
+
+    state->dataOutAirNodeMgr->OutsideAirNodeList(1) = 1;
+    state->dataOutAirNodeMgr->OutsideAirNodeList(2) = 2;
+
+    // Node 1: EMS overrides drybulb + wetbulb, but IsLocalNode is FALSE
+    // (simulates Python plugin API path — getActuatorHandle never sets IsLocalNode)
+    state->dataLoopNodes->Node(1).IsLocalNode = false;
+    state->dataLoopNodes->Node(1).EMSOverrideOutAirDryBulb = true;
+    state->dataLoopNodes->Node(1).EMSOverrideOutAirWetBulb = true;
+    state->dataLoopNodes->Node(1).EMSValueForOutAirDryBulb = 26.7;
+    state->dataLoopNodes->Node(1).EMSValueForOutAirWetBulb = 19.4;
+    state->dataLoopNodes->Node(1).OutAirDryBulb = state->dataEnvrn->OutDryBulbTemp;
+    state->dataLoopNodes->Node(1).OutAirWetBulb = state->dataEnvrn->OutWetBulbTemp;
+
+    // Node 2: EMS overrides only wetbulb, IsLocalNode is FALSE
+    state->dataLoopNodes->Node(2).IsLocalNode = false;
+    state->dataLoopNodes->Node(2).EMSOverrideOutAirWetBulb = true;
+    state->dataLoopNodes->Node(2).EMSValueForOutAirWetBulb = 19.4;
+    state->dataLoopNodes->Node(2).OutAirDryBulb = state->dataEnvrn->OutDryBulbTemp;
+    state->dataLoopNodes->Node(2).OutAirWetBulb = state->dataEnvrn->OutWetBulbTemp;
+
+    InitOutAirNodes(*state);
+
+    // Expected: HumRat recalculated from overridden Tdb=26.7 + Twb=19.4
+    Real64 expectedHumRat1 = Psychrometrics::PsyWFnTdbTwbPb(*state, 26.7, 19.4, state->dataEnvrn->OutBaroPress);
+    EXPECT_NEAR(expectedHumRat1, state->dataLoopNodes->Node(1).HumRat, 0.000001);
+    EXPECT_NEAR(26.7, state->dataLoopNodes->Node(1).Temp, 0.001);
+    EXPECT_NEAR(19.4, state->dataLoopNodes->Node(1).OutAirWetBulb, 0.001);
+
+    // Expected: HumRat recalculated from environment Tdb=25.0 + overridden Twb=19.4
+    Real64 expectedHumRat2 = Psychrometrics::PsyWFnTdbTwbPb(*state, 25.0, 19.4, state->dataEnvrn->OutBaroPress);
+    EXPECT_NEAR(expectedHumRat2, state->dataLoopNodes->Node(2).HumRat, 0.000001);
+    EXPECT_NEAR(19.4, state->dataLoopNodes->Node(2).OutAirWetBulb, 0.001);
+}