diff --git a/doc/ChangeLog b/doc/ChangeLog
index 676bcae485..355c7c1133 100644
--- a/doc/ChangeLog
+++ b/doc/ChangeLog
@@ -1,5 +1,74 @@
 ===============================================================
 
+Tag name: cam6_3_151
+Originator(s): eaton
+Date: Thu 21 Mar 2024
+One-line Summary: Bugfix to allow multiple monthly avg history files
+Github PR URL: https://github.com/ESCOMP/CAM/pull/1003
+
+Purpose of changes (include the issue number and title text for each relevant GitHub issue):
+
+#1000 - Output of more than 1 monthly average history file is broken.
+
+. resolves #1000
+
+Describe any changes made to build system: none
+
+Describe any changes made to the namelist: none
+
+List any changes to the defaults for the boundary datasets: none
+
+Describe any substantial timing or memory changes: none
+
+Code reviewed by: cacraigucar, peverwhee
+
+List all files eliminated: none
+
+List all files added and what they do: none
+
+List all existing files that have been modified, and describe the changes:
+
+src/control/cam_history.F90
+. subroutine wshist
+  - add new local variables to store the year, month, and day components of
+    the time interval midpoint date.
+
+If there were any failures reported from running test_driver.sh on any test
+platform, and checkin with these failures has been OK'd by the gatekeeper,
+then copy the lines from the td.*.status files for the failed tests to the
+appropriate machine below.  All failed tests must be justified.
+
+All tests have a MEMCOMP failure which we are ignoring.
+Several tests have a TPUTCOMP failure which we are also ignoring.
+
+derecho/intel/aux_cam:
+  ERP_Ln9.C96_C96_mg17.F2000climo.derecho_intel.cam-outfrq9s_mg3 (Overall: FAIL) details:
+  ERP_Ln9.f09_f09_mg17.FCSD_HCO.derecho_intel.cam-outfrq9s (Overall: FAIL) details:
+  SMS_Ld1.f09_f09_mg17.FCHIST_GC.derecho_intel.cam-outfrq1d (Overall: FAIL) details:
+  SMS_Lh12.f09_f09_mg17.FCSD_HCO.derecho_intel.cam-outfrq3h (Overall: DIFF) details:
+  - pre-existing failures
+
+izumi/nag/aux_cam:
+  DAE.f45_f45_mg37.FHS94.izumi_nag.cam-dae (Overall: FAIL) details:
+  - pre-existing failure
+
+izumi/gnu/aux_cam:
+  All PASS.
+
+TESTING NOTE: None of our regression tests use multiple monthly output
+files.  The fix was tested in a low res FHS94 compset that specified
+monthly output for h0, h1, h2, and h3.  The 'T' field was output in each
+file.  A 1 month test was run and all files had identical output.  This is
+the same configuration that I used to debug the problem.
+
+CAM tag used for the baseline comparison tests if different than previous
+tag:
+
+Summarize any changes to answers: BFB
+
+===============================================================
+===============================================================
+
 Tag name: cam6_3_150
 Originator(s): megandevlan, peverwhee
 Date: Feb 23, 2024
diff --git a/src/control/cam_history.F90 b/src/control/cam_history.F90
index 28e1d848f2..a0b35e5a1d 100644
--- a/src/control/cam_history.F90
+++ b/src/control/cam_history.F90
@@ -5516,6 +5516,7 @@ subroutine wshist (rgnht_in)
 #endif
 
     integer :: yr, mon, day      ! year, month, and day components of a date
+    integer :: yr_mid, mon_mid, day_mid ! year, month, and day components of midpoint date
     integer :: nstep             ! current timestep number
     integer :: ncdate(maxsplitfiles) ! current (or midpoint) date in integer format [yyyymmdd]
     integer :: ncsec(maxsplitfiles)  ! current (or midpoint) time of day [seconds]
@@ -5529,7 +5530,6 @@ subroutine wshist (rgnht_in)
     logical :: prev              ! Label file with previous date rather than current
     logical :: duplicate         ! Flag for duplicate file name
     integer :: ierr
-    integer :: ncsec_temp
 #if ( defined BFB_CAM_SCAM_IOP )
     integer :: tsec             ! day component of current time
     integer :: dtime            ! seconds component of current time
@@ -5583,6 +5583,7 @@ subroutine wshist (rgnht_in)
            end if
         end if
       end if
+
       time = ndcur + nscur/86400._r8
       if (is_initfile(file_index=t)) then
         tdata = time   ! Inithist file is always instantanious data
@@ -5590,10 +5591,12 @@ subroutine wshist (rgnht_in)
         tdata(1) = beg_time(t)
         tdata(2) = time
       end if
+
       ! Set midpoint date/datesec for accumulated file
-      call set_date_from_time_float((tdata(1) + tdata(2)) / 2._r8, yr, mon, day, ncsec_temp)
-      ncsec(accumulated_file_index) = ncsec_temp
-      ncdate(accumulated_file_index) = yr*10000 + mon*100 + day
+      call set_date_from_time_float((tdata(1) + tdata(2)) / 2._r8, &
+         yr_mid, mon_mid, day_mid, ncsec(accumulated_file_index) )
+      ncdate(accumulated_file_index) = yr_mid*10000 + mon_mid*100 + day_mid
+
       if (hstwr(t) .or. (restart .and. rgnht(t))) then
         if(masterproc) then
           if(is_initfile(file_index=t)) then
@@ -5609,7 +5612,7 @@ subroutine wshist (rgnht_in)
               if (f == instantaneous_file_index) then
                 write(iulog,200) nfils(t),'instantaneous',t,yr,mon,day,ncsec(f)
               else
-                write(iulog,200) nfils(t),'accumulated',t,yr,mon,day,ncsec(f)
+                write(iulog,200) nfils(t),'accumulated',t,yr_mid,mon_mid,day_mid,ncsec(f)
               end if
 200           format('WSHIST: writing time sample ',i3,' to ', a, ' h-file ', &
                    i1,' DATE=',i4.4,'/',i2.2,'/',i2.2,' NCSEC=',i6)