Monthly outlook for Portal, MT: average high 43.7°, average low 25.2°. That is 2.7° below the climate normal for October. Precipitation is expected on 6 days (about 2.4 inches), against a normal of 4 days and 0.7 inches. The warmest day looks like 22 October (61.8°), the coolest 28 October (15.8°).
43.7°/25.2°
Average high / low
−2.7°
Below normal
6 / 4
Wet days / normal
2.4 in
Precipitation this month
Ten-day blocks vs climate normal
Period
Forecast high
Normal
Difference
21 October – 30 October
45°
50.3°
-2.9°
31 October – 9 November
41.4°
44.6°
-1.8°
10 November – 19 November
at normal
40.6°
—
October records over 66 years
83.5°1 October 2011All-time high
-11.2°28 October 2023All-time low
Climate normals and records are computed from the nearest reference point — Jefferson City (5 mi).
Thu, 2262° / 37°0
62 °
Portal, Thursday, 22 October
Clear. High 62°, low 37°.
Pressure29.88 inHg
Wind7.3 mph S
Humidity49%
Visibility6.2 mi
Dew point39°
Fri, 2343° / 27°1.17
43 °
Portal, Friday, 23 October
Snow. High 43°, low 27°.
Pressure29.83 inHg
Wind8.9 mph N
Humidity99%
Visibility1.5 mi
Dew point41°
Sat, 2436° / 16°0
36 °
Portal, Saturday, 24 October
Partly cloudy. High 36°, low 16°.
Pressure30.36 inHg
Wind4.7 mph S
Humidity88%
Visibility6.2 mi
Dew point24°
Sun, 2537° / 22°0
37 °
Portal, Sunday, 25 October
Partly cloudy. High 37°, low 22°.
Pressure30.30 inHg
Wind5.3 mph SW
Humidity75%
Visibility—
Dew point27°
Mon, 2643° / 21°0.28
43 °
Portal, Monday, 26 October
Snow. High 43°, low 21°.
Pressure30.21 inHg
Wind6.2 mph SW
Humidity70%
Visibility—
Dew point28°
Tue, 2732° / 17°0.07
32 °
Portal, Tuesday, 27 October
Light snow. High 32°, low 17°.
Pressure30.18 inHg
Wind11.7 mph W
Humidity66%
Visibility—
Dew point20°
Wed, 2839° / 16°0
39 °
Portal, Wednesday, 28 October
Mostly clear. High 39°, low 16°.
Pressure30.39 inHg
Wind4.9 mph W
Humidity71%
Visibility—
Dew point25°
Thu, 2946° / 21°0
46 °
Portal, Thursday, 29 October
Overcast. High 46°, low 21°.
Pressure30.12 inHg
Wind4.3 mph SW
Humidity67%
Visibility—
Dew point28°
Fri, 3051° / 26°0
51 °
Portal, Friday, 30 October
Clear. High 51°, low 26°.
Pressure29.83 inHg
Wind5.6 mph SW
Humidity55%
Visibility—
Dew point30°
Sat, 3153° / 33°0
53 °
Portal, Saturday, 31 October
Partly cloudy. High 53°, low 33°.
Pressure29.68 inHg
Wind5.3 mph SW
Humidity55%
Visibility—
Dew point33°
Sun, 0152° / 36°0
52 °
Portal, Sunday, 1 November
Partly cloudy. High 52°, low 36°.
Pressure29.80 inHg
Wind8.7 mph SW
Humidity55%
Visibility—
Dew point33°
Mon, 0249° / 37°0.47
49 °
Portal, Monday, 2 November
Rain. High 49°, low 37°.
Pressure29.65 inHg
Wind6 mph SW
Humidity62%
Visibility—
Dew point34°
Tue, 0333° / 20°0.34
33 °
Portal, Tuesday, 3 November
Snow. High 33°, low 20°.
Pressure30.18 inHg
Wind10.6 mph N
Humidity84%
Visibility—
Dew point21°
Wed, 0427° / 19°0.04
27 °
Portal, Wednesday, 4 November
Light snow. High 27°, low 19°.
Pressure30.33 inHg
Wind6.3 mph N
Humidity58%
Visibility—
Dew point12°
Thu, 0533° / 21°0.01
33 °
Portal, Thursday, 5 November
Light snow. High 33°, low 21°.
Pressure30.39 inHg
Wind4.6 mph N
Humidity47%
Visibility—
Dew point12°
From day 17 onward the outlook is built from 60-year climate statistics
Fri, 0644° / 27°0.05
44 °
Portal, Friday, 6 November
Climate normal for this date — 60-year average.
Average high44°
Average low27°
Average precipitation0.05 in
Chance of precipitation27%
Record high62° (2010)
Record low5° (2003)
Sat, 0744° / 28°0.04
44 °
Portal, Saturday, 7 November
Climate normal for this date — 60-year average.
Average high44°
Average low28°
Average precipitation0.04 in
Chance of precipitation32%
Record high62° (2010)
Record low2° (2017)
Sun, 0842° / 27°0.07
42 °
Portal, Sunday, 8 November
Climate normal for this date — 60-year average.
Average high42°
Average low27°
Average precipitation0.07 in
Chance of precipitation35%
Record high61° (2016)
Record low6° (2022)
Mon, 0942° / 25°0.04
42 °
Portal, Monday, 9 November
Climate normal for this date — 60-year average.
Average high42°
Average low25°
Average precipitation0.04 in
Chance of precipitation28%
Record high64° (2016)
Record low-5° (2020)
Tue, 1041° / 24°0.04
41 °
Portal, Tuesday, 10 November
Climate normal for this date — 60-year average.
Average high41°
Average low24°
Average precipitation0.04 in
Chance of precipitation25%
Record high63° (2025)
Record low-17° (1986)
Wed, 1141° / 23°0.03
41 °
Portal, Wednesday, 11 November
Climate normal for this date — 60-year average.
Average high41°
Average low23°
Average precipitation0.03 in
Chance of precipitation23%
Record high62° (2016)
Record low-12° (2000)
Thu, 1242° / 25°0.03
42 °
Portal, Thursday, 12 November
Climate normal for this date — 60-year average.
Average high42°
Average low25°
Average precipitation0.03 in
Chance of precipitation20%
Record high65° (1999)
Record low-10° (1986)
Fri, 1342° / 26°0.04
42 °
Portal, Friday, 13 November
Climate normal for this date — 60-year average.
Average high42°
Average low26°
Average precipitation0.04 in
Chance of precipitation23%
Record high63° (1999)
Record low-3° (2000)
Sat, 1441° / 25°0.03
41 °
Portal, Saturday, 14 November
Climate normal for this date — 60-year average.
Average high41°
Average low25°
Average precipitation0.03 in
Chance of precipitation23%
Record high62° (1999)
Record low1° (2000)
Sun, 1541° / 24°0.02
41 °
Portal, Sunday, 15 November
Climate normal for this date — 60-year average.
Average high41°
Average low24°
Average precipitation0.02 in
Chance of precipitation17%
Record high59° (1999)
Record low1° (2005)
Mon, 1641° / 25°0.04
41 °
Portal, Monday, 16 November
Climate normal for this date — 60-year average.
Average high41°
Average low25°
Average precipitation0.04 in
Chance of precipitation27%
Record high57° (2001)
Record low0° (1961)
Tue, 1740° / 24°0.04
40 °
Portal, Tuesday, 17 November
Climate normal for this date — 60-year average.
Average high40°
Average low24°
Average precipitation0.04 in
Chance of precipitation25%
Record high56° (1999)
Record low-2° (1968)
Wed, 1839° / 23°0.05
39 °
Portal, Wednesday, 18 November
Climate normal for this date — 60-year average.
Average high39°
Average low23°
Average precipitation0.05 in
Chance of precipitation30%
Record high58° (2008)
Record low-12° (2022)
Thu, 1938° / 22°0.06
38 °
Portal, Thursday, 19 November
Climate normal for this date — 60-year average.
Average high38°
Average low22°
Average precipitation0.06 in
Chance of precipitation28%
Record high53° (1989)
Record low-3° (1978)
About the monthly outlook
How accurate is a 30-day forecast?
The first 16 days come from weather models — reliable for the first 3–5 days and progressively less so after that. Days 17 through 30 for Portal, MT are built from the climate normal, the 60-year average, so they show typical weather for those dates rather than a specific forecast.
What does "above normal" mean?
We compare the forecast against the climate normal for those exact calendar days, computed from 60 years of observations. The deviation shows how much the coming month differs from a typical one.
Where do the 66-year records come from?
They are real temperature extremes recorded in Portal, MT since 1960: the highest and lowest reading for each calendar date, with the year it happened.
How often is it updated?
The forecast portion refreshes every hour; the climate portion is based on long-term data and stays stable.