diff --git a/static/js/app.js b/static/js/app.js
index 94ca198..4c5d231 100644
--- a/static/js/app.js
+++ b/static/js/app.js
@@ -170,20 +170,23 @@ const WeatherApp = {
                 try {
                     const hexID = WeatherUtils.decimalToHex(decimalId);
                     const stationID = `RS485-${hexID}`;
-                    const endPlus3Str = (() => {
-                        try {
-                            const d = new Date(endTime);
-                            if (!isNaN(d)) {
-                                const d2 = new Date(d.getTime() + 3 * 60 * 60 * 1000);
-                                return WeatherUtils.formatDatetimeLocal(d2).replace('T', ' ') + ':00';
-                            }
-                        } catch (e) {}
-                        return endTime.replace('T', ' ') + ':00';
-                    })();
+                    // 将预报查询范围按小时对齐：from 向下取整到整点；to 向上取整到整点，再 +3h
+                    const parseLocal = (s) => { try { return new Date(s); } catch { return null; } };
+                    const floorHour = (d) => { const t = new Date(d); t.setMinutes(0,0,0); return t; };
+                    const ceilHour = (d) => { const t = new Date(d); if (t.getMinutes()||t.getSeconds()||t.getMilliseconds()) { t.setHours(t.getHours()+1); } t.setMinutes(0,0,0); return t; };
+                    const fmt = (d) => {
+                        const y=d.getFullYear(); const m=String(d.getMonth()+1).padStart(2,'0'); const da=String(d.getDate()).padStart(2,'0');
+                        const h=String(d.getHours()).padStart(2,'0'); const mi='00'; const s='00';
+                        return `${y}-${m}-${da} ${h}:${mi}:${s}`;
+                    };
+                    const startD = parseLocal(startTime);
+                    const endD = parseLocal(endTime);
+                    const fromStr = startD && !isNaN(startD) ? fmt(floorHour(startD)) : startTime.replace('T',' ') + ':00';
+                    const toStr = endD && !isNaN(endD) ? fmt(new Date(ceilHour(endD).getTime() + 3*60*60*1000)) : endTime.replace('T',' ') + ':00';
                     const forecastParams = new URLSearchParams({
                         station_id: stationID,
-                        from: startTime.replace('T', ' ') + ':00',
-                        to: endPlus3Str,
+                        from: fromStr,
+                        to: toStr,
                         provider: forecastProvider,
                         versions: '3'
                     });
@@ -250,4 +253,4 @@ window.WeatherApp = WeatherApp;
 
 document.addEventListener('DOMContentLoaded', () => {
     WeatherApp.init();
-}); 
\ No newline at end of file
+});