Billings, Montana 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

744
FXUS65 KBYZ 201940
AFDBYZ

Area Forecast Discussion
National Weather Service Billings MT
140 PM MDT Sun Jul 20 2025

.KEY MESSAGES...

- Scattered afternoon and evening showers/t-storms today and
  Monday. Some storms could be severe and produce large hail,
  strong winds, and heavy rain. The risk of severe storms is in
  our east today, and across the entire region Monday.

- Cooler temperatures (70s and 80s) Tuesday and Wednesday with
  continued daily chances of showers and thunderstorms.

- More typical July weather (warmer and drier) looks to return
  for Thursday into the weekend.

&&

.DISCUSSION...
Through Monday Night...

The next round of convection seems to be starting in our west at
19z, with BLX radar showing a few showers and embedded lightning
along an axis from the Absaroka Mountains to western Musselshell
County. This activity is tied to the arrival of a mid level speed
max over central MT. The air mass over our west is on the drier
side and convection should mostly weak, though erratic wind gusts
are possible per steep low level lapse rates. Moisture and
instability are much greater over the east and mesoanalysis shows
1500-2000 J/kg of MLCape east of Rosebud County with little to no
CIN and plenty of bulk shear. Satellite imagery shows areas of
flat cumulus over the eastern hills but the lack of vertical
growth suggests there is still too much capping. As the forcing in
central MT tracks to the east we expect the t-storm risk to do
likewise. Storms from Rosebud to Sheridan County eastward have the
potential to be severe and produce large hail, strong wind gusts
and heavy rain (pwats remain over an inch).

CAMs continue to show a variety of solutions over our east for
the next 6-12 hours, with the HRRR being notably erratic from run
to run. Will need to monitor the mesoanalysis, but the lack of
stronger E-SE low level flow is suggestive of weaker storms and
probably less coverage than we saw yesterday. That said, cannot
discount the instability and bulk shear, along with an approaching
shortwave. The day1 outlook has been updated to show a slight
risk of severe t-storms east of Hysham-Lodge Grass. Stay alert if
you have outdoor plans!

Some models show some nocturnal convection redeveloping over our
northeast overnight, and this is possible given the easterly
surface winds, but do not expect much of a low level jet behind
the aforementioned shortwave, so there is plenty of uncertainty
here as well. Will keep lower pops near Miles City, Baker and
Ekalaka from 06-12Z to cover this potential. Storms or not, there
is a good chance (60%) that fog/stratus will impact our far east
again late tonight and early Monday.

Pacific coast trof deepens tomorrow allowing for backing and
increasingly diffluent SW flow aloft. This sets up another period
of showers and thunderstorms beginning in the afternoon. Easterly
surface winds increase and pwats rise a bit higher, thus we are
looking at potential for strong to severe storms and heavy rain
across our entire cwa. This activity will lift to the northeast
and exit our cwa late tomorrow night. This will coincide with a
push of higher pressures/cooler air from the north, and the
possibility for lower clouds and/or fog across most of the area.

Temps today will reach the 80s to near 90F. Cooling will start in
our NW on Monday (highs in lower-mid 80s), while the south sees a
brief push into the lower 90s before the cold advection arrives
in the evening. This will set the stage for more pronounced
midweek cooling.

JKL

Tuesday through Saturday...

Shortwave troughing set to move through Tuesday through Thursday
morning will allow for southwest flow to continue as well as
increased chances of precipitation. The best chance of strong to
severe thunderstorms looks to be Tuesday afternoon with sufficient
instability and shear present. Into Wednesday, instability will
slightly decrease, but a few strong thunderstorms are still possible.
Showers associated with this system will dissipate early Thursday
morning. Chances for at least a quarter inch of rain with this
system is about 40-70% for most of the region. Heavy rain can
continue to be expected under any stronger thunderstorms given
moderate to high atmospheric moisture. Into Thursday, drier air
will fill in behind troughing as westerly flow builds in.
However, a split flow will begin to develop over northern WY,
putting areas of southern MT and northern WY under southwest flow.
This will allow for small (10-30%) chances of showers and
thunderstorms for the MT/WY border Thursday afternoon. Ensembles
are hinting at bringing in a more pronounced southwest flow into
next weekend, thus increasing chances for showers and
thunderstorms.

Temperatures Tuesday and Wednesday will be slightly cooler than
normal with highs forecast to be in the 70s to low 80s.
Temperatures will rebound back to near normal (80s, low 90s),
reaching the mid 90s by the weekend. TS

&&

.AVIATION...

Expect scattered t-storms late this afternoon and evening, some
of which may be severe and produce heavy rain (and local
reductions to IFR) especially east of KBIL. Convection will
initially develop over the Beartooth Range and move off to the
eastern plains after 20Z. Storms may linger past midnight near the
Dakotas border, but there is uncertainty here. Areas of fog and
stratus (reductions to MVFR to IFR) are likely to occur again
tonight into early Monday east of Rosebud County (60% chance).

After a break late tonight and Monday morning, the next round of
showers and t-storms arrives tomorrow afternoon. Tomorrow`s storms
also could become severe and produce heavy rain along with
reductions to MVFR or IFR. All TAF sites will be at risk of TS
impacts on Monday.

JKL

&&

.PRELIMINARY POINT TEMP/POPS...

    Mon     Tue     Wed     Thu     Fri     Sat     Sun
-----------------------------------------------------------
BIL 060/088 059/082 060/080 059/087 060/091 061/093 061/092
    23/T    44/T    65/T    31/U    11/U    10/U    10/U
LVM 050/085 050/081 053/082 049/086 051/089 053/090 053/090
    25/T    46/T    55/T    22/T    11/U    11/U    10/U
HDN 059/090 059/083 059/081 057/088 058/092 059/094 060/093
    33/T    32/T    65/T    41/U    21/U    10/U    10/U
MLS 062/089 062/083 061/081 059/088 061/092 063/095 063/094
    42/T    51/B    54/T    51/U    21/U    10/U    10/U
4BQ 062/093 062/084 063/079 061/084 062/088 062/092 063/093
    22/T    41/B    64/T    61/U    31/U    10/U    10/U
BHK 058/086 061/084 058/079 057/084 057/088 059/090 059/090
    41/B    51/B    53/T    61/U    31/U    11/U    11/U
SHR 054/092 058/084 055/080 053/086 054/088 056/092 057/092
    23/T    22/T    55/T    42/T    21/U    10/U    00/U

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...None.
WY...None.

&&

$$
weather.gov/billings