diff --git a/apps/fo/app/pages/dashboard/rainManage/page.tsx b/apps/fo/app/pages/dashboard/rainManage/page.tsx
index ea20eb92c..9bceed75e 100644
--- a/apps/fo/app/pages/dashboard/rainManage/page.tsx
+++ b/apps/fo/app/pages/dashboard/rainManage/page.tsx
@@ -45,6 +45,7 @@ export default function RainManageTab({searchYear = '', fcltyList = []}: facilit
   }, [searchYear]);
   
   return (
+    <div>
     <UiTable 
       headName=""
       tableData={rainManageList}
@@ -55,5 +56,7 @@ export default function RainManageTab({searchYear = '', fcltyList = []}: facilit
       onPageChange={() => {}}
     >
     </UiTable>
+      <span className="text-2xl font-bold text-gray-500">☞ 일수에 강우영향일 포함됨</span>
+    </div>
   )
 }
diff --git a/apps/fo/app/store/flowRate/index.tsx b/apps/fo/app/store/flowRate/index.tsx
index 38cb4e2e6..fecf65e44 100644
--- a/apps/fo/app/store/flowRate/index.tsx
+++ b/apps/fo/app/store/flowRate/index.tsx
@@ -320,37 +320,49 @@ export const flowRateSearchReducer:(set:(fn: (state: FlowRateSearchType) => Flow
                 }
             });
 
-            // facilityPrecipitation의 rainEffectDay 계산 로직을 적용
+            // 강우영향일 계산 (강우량이 3 초과이면 무조건 강우영향일)
             for(let idx = 0; idx < data.length; idx++) {
                 const item = data[idx];
-                const rainDay = Number(item.infoRnDay) >= 3 ? 1 : 0;
-                let rainEffectDay = 0;
-                
-                if(idx < data.length - 2) {
-                    if(rainDay == 1) {
-                        rainEffectDay = 1;
+                if(item){
+                    if(item.infoRnDay && Number(item.infoRnDay) > 3) {
+                        item.rainEffectDay = 1;
                     } else {
-                        if(idx >= 2) {
-                            if(Number(data[idx-1].infoRnDay) >= 3 || Number(data[idx-2].infoRnDay) >= 3) {
-                                rainEffectDay = 1;
-                            }
-                        }
+                        item.rainEffectDay = 0;
                     }
-                } else if(idx < data.length - 1) {
-                    if(rainDay == 1 || Number(data[idx+1].infoRnDay) >= 3) {
-                        rainEffectDay = 1;
-                    }
-                } else {
-                    rainEffectDay = rainDay;
                 }
-
-                tmpData.push({
-                    ...item,
-                    rainEffectDay: rainEffectDay,
-                });
             }
 
-            const rtnData = tmpData.map((item: FlowRateModalProps) => {
+            // 이틀 전, 하루 전이 강우영향일(3 이상)인 경우 해당 날도 강우영향일로 설정
+            for(let idx = 0; idx < data.length; idx++) {
+                if(data[idx]) {
+                    // 하루 전이 강우영향일(3 이상)인 경우
+                    if(idx > 0 && data[idx-1]?.infoRnDay && Number(data[idx-1]?.infoRnDay) >= 3) {
+                        data[idx]!.rainEffectDay = 1;
+                    }
+                    // 이틀 전이 강우영향일(3 이상)인 경우
+                    if(idx > 1 && data[idx-2]?.infoRnDay && Number(data[idx-2]?.infoRnDay) >= 3) {
+                        data[idx]!.rainEffectDay = 1;
+                    }
+                }
+            }
+
+            for(let idx = 0; idx < data.length; idx++) {
+                if(data[idx] && data[idx]?.rainEffectDay === 1) {
+                    if(idx > 1){
+                        if(data[idx-1]?.infoRnDay && Number(data[idx-1]?.infoRnDay) > 3) {
+                            data[idx]!.infoRnDay = data[idx-1]!.infoRnDay;
+                        }
+                    }
+                    if(idx > 2){
+                        if(data[idx-2]?.infoRnDay && Number(data[idx-2]?.infoRnDay) > 3) {
+                            data[idx]!.infoRnDay = data[idx-2]!.infoRnDay;
+                        }
+                    }
+                }
+            }
+
+            console.log('data', data);
+            const rtnData = data.map((item: FlowRateModalProps) => {
                 item.totInflAmnt = Number(item.inflAmnt || 0) + Number(item.sumFlow || 0) + Number(item.returnAmnt || 0)
                 dataFormSetting(item);
                 return item;