834  
FXUS65 KBOI 211556  
AFDBOI  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE BOISE ID  
956 AM MDT TUE OCT 21 2025  
   
DISCUSSION
 
BELOW FREEZING TEMPERATURES WERE EXPERIENCED LAST  
NIGHT ACROSS MOST OF THE TREASURE VALLEY AND MAGIC VALLEY  
AGRICULTURAL AREAS WHICH BRINGS THE 2025 GROWING SEASON TO AN  
END. GIVEN THAT THE GROWING SEASON NORMALLY ENDS IN MID TO LATE  
OCTOBER, NO ADDITIONAL FROST OR FREEZE WARNINGS WILL BE ISSUED  
IN 2025. VERY DRY AIR WITH CLEAR SKIES WILL ALLOW TEMPERATURES  
TO RAPIDLY WARM TO NEAR NORMAL ACROSS THE AREA FOR A PLEASANT  
AFTERNOON WITH LIGHT WINDS. TONIGHT'S TEMPERATURES WILL NOT BE  
QUITE AS COLD AS THEY WERE EARLY THIS MORNING, BUT TEMPERATURES  
WILL DROP QUICKLY AGAIN AFTER SUNSET FALLING TO NEAR OR BELOW  
FREEZING IN MOST AREAS. FOG IS LIKELY AGAIN TONIGHT IN PORTIONS  
OF VALLEY COUNTY, ESPECIALLY IN THE VICINITY OF LAKE CASCADE.  
 

 
   
AVIATION
 
VFR. PATCHY MOUNTAIN VALLEY FOG THIS MORNING. SURFACE  
WINDS: VARIABLE LESS THAN 10 KT. WINDS ALOFT AT 10KFT MSL: SW-W 10-  
20 KT.  
 
KBOI...VFR. SURFACE WINDS: LIGHT AND VARIABLE, AFTER SUNSET BECOMING  
SE 4-9 KT.  
 

 
   
PREV DISCUSSION
 
 
SHORT TERM...TODAY THROUGH THURSDAY NIGHT...WEAK RIDGING IS  
BUILDING ACROSS THE REGION, WITH A WARMING AND DRYING TREND  
TAKING OVER THROUGH THE SHORT TERM PERIOD. LIGHT SOUTHEAST  
WINDS AND WARMER DAYTIME HIGH TEMPERATURES WILL KEEP  
TEMPERATURES SLIGHTLY WARMER TOMORROW NIGHT, BUT LIGHT WINDS  
THIS MORNING WILL ALLOW FOR TEMPERATURES NEAR FREEZING IN LOWER  
ELEVATION VALLEYS. THEREFORE, THE FREEZE WARNING IS STILL IN  
EFFECT FOR THE SNAKE RIVER VALLEY. AREAS IN BOISE AND ALONG THE  
FOOTHILLS WILL STAY ABOVE FREEZING THANKS TO SLIGHTLY ELEVATED  
SOUTHEAST WINDS, BUT LOWER ELEVATION AND SHELTERED AREAS WILL  
SEE TEMPERATURES DIP TO THE UPPER 20S AND LOW 30S. TEMPERATURES  
NEAR ONTARIO AND CALDWELL ARE ALREADY NEAR 33-36F AS OF 3:00AM  
MDT.NO ADDITIONAL FROST OR FREEZE WARNINGS WILL BE ISSUED  
IN 2025.  
 
A LOW PRESSURE SYSTEM WILL MOVE TO OUR SOUTH ON WEDNESDAY,  
BRINGING SOME CLOUD COVER TO SOUTHERN PORTIONS OF THE REGION.  
THE RISK OF PRECIPITATION IS NEARLY NONEXISTENT, AS THE LOW  
CENTER IS PROJECTED TO STAY FAR TO OUR SOUTH.  
 
LONG TERM...FRIDAY THROUGH TUESDAY...A DEEP TROUGH OVER THE  
GULF OF ALASKA WILL HELP ADVECT A PLUME OF MOISTURE INTO THE  
NORTHWEST BEGINNING LATE FRIDAY. THIS ATMOSPHERIC RIVER WILL  
BRING PRECIPITATION TO THE AREA BY EARLY SATURDAY, BUT WARM  
SOUTHWEST FLOW AHEAD OF THE MAIN COLD AIR MASS WILL KEEP  
TEMPERATURES ABOVE NORMAL ON FRIDAY AND SATURDAY. TEMPERATURES  
WILL THEN PLUMMET 10 TO 15 DEGREES ON SUNDAY AS COLD AIR, GUSTY  
WINDS, AND SIGNIFICANT MOISTURE MOVES INTO THE REGION. SNOW  
LEVELS WILL BE AROUND 7000-8000 FEET MSL THROUGH SATURDAY,  
DROPPING TO 4000-5000 FEET MSL ON SUNDAY AND MONDAY. WIDESPREAD  
VALLEY RAIN AND HEAVY MOUNTAIN SNOW IS ANTICIPATED, WITH 2 DAY  
SNOWFALL TOTALS REACHING UP TO 8 TO 12 INCHES FOR HIGHER SUMMITS  
WITH 1-3 INCHES FOR MOUNTAIN VALLEYS BY MONDAY MORNING. MODELS  
REMAIN IN LOCKSTEP WITH THIS SYSTEM, WITH ONLY SLIGHT VARIATIONS  
ON TIMING OF THE INITIAL PRECIPITATION ON SATURDAY.  
 
BY LATE MONDAY, THE TROUGH LOOKS TO MOVE TO OUR EAST AND DEEPEN  
OVER THE GREAT PLAINS. THIS WILL KEEP US IN COOL NORTHWEST FLOW  
LATE MONDAY INTO TUESDAY, WITH SOME LINGERING MOISTURE OVER  
HIGH TERRAIN PRODUCING SOME STRAY SHOWERS. A RIDGE OF HIGH  
PRESSURE LOOKS TO THEN DEVELOP ACROSS THE WESTERN US BY TUESDAY,  
BRINGING ABOVE NORMAL TEMPERATURES AND DRY CONDITIONS.  
 

 
   
BOI WATCHES/WARNINGS/ADVISORIES
 
 
ID...NONE.  
OR...NONE.  
 

 
 

 
 
WWW.WEATHER.GOV/BOISE  
 
INTERACT WITH US VIA SOCIAL MEDIA:  
WWW.FACEBOOK.COM/NWSBOISE  
WWW.X.COM/NWSBOISE  
 
DISCUSSION...JB  
AVIATION.....CH  
SHORT TERM...SA  
LONG TERM....SA  
 
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