diff --git a/CHANGELOG.md b/CHANGELOG.md
index 483820b42..8ba96b2a4 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,9 @@ This file documents all notable changes to the GEOS-Chem repository starting in
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/), and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## [Unreleased] - TBD
+### Added
+- Added allocate guards for arrays in `pressure_mod`
+
 ### Changed
 - Renamed `Emiss_Carbon_Gases` to `CO2_Production` in `carbon_gases_mod.F90`
 - Updated start date and restart file for CO2 and tagCO simulations for consistency with carbon simulations
diff --git a/GeosUtil/pressure_mod.F90 b/GeosUtil/pressure_mod.F90
index f81a1268d..f8de6e71e 100644
--- a/GeosUtil/pressure_mod.F90
+++ b/GeosUtil/pressure_mod.F90
@@ -517,42 +517,57 @@ SUBROUTINE INIT_PRESSURE( Input_Opt, State_Grid, RC )
     RC      = GC_SUCCESS
     ThisLoc = ' -> at Init_Pressure (in GeosUtil/pressure_mod.F90)'
 
-    ALLOCATE( PFLT_DRY( State_Grid%NX, State_Grid%NY ), STAT=RC )
-    CALL GC_CheckVar( 'vdiff_mod.F90:PFLT_DRY', 2, RC )
-    IF ( RC /= GC_SUCCESS ) RETURN
-    PFLT_DRY = 0e+0_fp
-
-    ALLOCATE( PFLT_WET( State_Grid%NX, State_Grid%NY ), STAT=RC )
-    CALL GC_CheckVar( 'vdiff_mod.F90:PFLT_WET', 2, RC )
-    IF ( RC /= GC_SUCCESS ) RETURN
-    PFLT_WET = 0e+0_fp
-
-    ALLOCATE( AP( State_Grid%NZ+1 ), STAT=RC )
-    CALL GC_CheckVar( 'vdiff_mod.F90:AP', 2, RC )
-    IF ( RC /= GC_SUCCESS ) RETURN
-    AP = 1e+0_fp
-
-    ALLOCATE( BP( State_Grid%NZ+1 ), STAT=RC )
-    CALL GC_CheckVar( 'vdiff_mod.F90:BP', 2, RC )
-    IF ( RC /= GC_SUCCESS ) RETURN
-    BP = 0e+0_fp
-
-    ALLOCATE( AP_FULLGRID( State_Grid%NativeNZ+1 ), STAT=RC )
-    CALL GC_CheckVar( 'vdiff_mod.F90:AP_FULLGRID', 2, RC )
-    IF ( RC /= GC_SUCCESS ) RETURN
-    AP = 1e+0_fp
-
-    ALLOCATE( BP_FULLGRID( State_Grid%NativeNZ+1 ), STAT=RC )
-    CALL GC_CheckVar( 'vdiff_mod.F90:BP_FULLGRID', 2, RC )
-    IF ( RC /= GC_SUCCESS ) RETURN
-    BP = 0e+0_fp
+    IF (.NOT. ALLOCATED( PFLT_DRY )) THEN
+      ALLOCATE( PFLT_DRY( State_Grid%NX, State_Grid%NY ), STAT=RC )
+      CALL GC_CheckVar( 'vdiff_mod.F90:PFLT_DRY', 2, RC )
+      IF ( RC /= GC_SUCCESS ) RETURN
+      PFLT_DRY = 0e+0_fp
+    END IF
+
+    IF (.NOT. ALLOCATED( PFLT_WET )) THEN
+      ALLOCATE( PFLT_WET( State_Grid%NX, State_Grid%NY ), STAT=RC )
+      CALL GC_CheckVar( 'vdiff_mod.F90:PFLT_WET', 2, RC )
+      IF ( RC /= GC_SUCCESS ) RETURN
+      PFLT_WET = 0e+0_fp
+    END IF
+
+    IF (.NOT. ALLOCATED( AP )) THEN
+      ALLOCATE( AP( State_Grid%NZ+1 ), STAT=RC )
+      CALL GC_CheckVar( 'vdiff_mod.F90:AP', 2, RC )
+      IF ( RC /= GC_SUCCESS ) RETURN
+      AP = 1e+0_fp
+    END IF
+
+    IF (.NOT. ALLOCATED( BP )) THEN
+      ALLOCATE( BP( State_Grid%NZ+1 ), STAT=RC )
+      CALL GC_CheckVar( 'vdiff_mod.F90:BP', 2, RC )
+      IF ( RC /= GC_SUCCESS ) RETURN
+      BP = 0e+0_fp
+    END IF
+
+    IF (.NOT. ALLOCATED( AP_FULLGRID )) THEN
+      ALLOCATE( AP_FULLGRID( State_Grid%NativeNZ+1 ), STAT=RC )
+      CALL GC_CheckVar( 'vdiff_mod.F90:AP_FULLGRID', 2, RC )
+      IF ( RC /= GC_SUCCESS ) RETURN
+      AP = 1e+0_fp
+    END IF
+
+    IF (.NOT. ALLOCATED( BP_FULLGRID )) THEN
+      ALLOCATE( BP_FULLGRID( State_Grid%NativeNZ+1 ), STAT=RC )
+      CALL GC_CheckVar( 'vdiff_mod.F90:BP_FULLGRID', 2, RC )
+      IF ( RC /= GC_SUCCESS ) RETURN
+      BP = 0e+0_fp
+    END IF
 
 #if defined( ESMF_ ) || defined( MODEL_ )
-    ALLOCATE( EXTERNAL_PEDGE( State_Grid%NX, State_Grid%NY, State_Grid%NZ+1 ), &
-              STAT=RC )
-    CALL GC_CheckVar( 'vdiff_mod.F90:EXTERNAL_PEDGE', 2, RC )
-    IF ( RC /= GC_SUCCESS ) RETURN
-    EXTERNAL_PEDGE = 0e+0_fp
+    IF (.NOT. ALLOCATED( EXTERNAL_PEDGE )) THEN
+      ALLOCATE( EXTERNAL_PEDGE( State_Grid%NX, State_Grid%NY, &
+                                State_Grid%NZ+1 ), &
+                STAT=RC )
+      CALL GC_CheckVar( 'vdiff_mod.F90:EXTERNAL_PEDGE', 2, RC )
+      IF ( RC /= GC_SUCCESS ) RETURN
+      EXTERNAL_PEDGE = 0e+0_fp
+    END IF
 #endif
 
     IF ( State_Grid%NZ == 47 ) THEN