Monthly outlook for Portal, MT: average high 46.1°, average low 28.7°. That is 2.7° below the climate normal for October. Precipitation is expected on 6 days (about 1.7 inches), against a normal of 4 days and 0.7 inches. The warmest day looks like 17 October (60.5°), the coolest 31 October (11.9°).
46.1°/28.7°
Average high / low
−2.7°
Below normal
6 / 4
Wet days / normal
1.7 in
Precipitation this month
Ten-day blocks vs climate normal
Period
Forecast high
Normal
Difference
17 October – 26 October
52.5°
53.2°
-0.4°
27 October – 5 November
35.3°
46.5°
-6.2°
6 November – 15 November
at normal
42.1°
—
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).
Sun, 1857° / 30°0
57 °
Portal, Sunday, 18 October
Overcast. High 57°, low 30°.
Pressure30.09 inHg
Wind3.7 mph S
Humidity46%
Visibility6.2 mi
Dew point30°
Mon, 1960° / 35°0
60 °
Portal, Monday, 19 October
Partly cloudy. High 60°, low 35°.
Pressure29.94 inHg
Wind6.3 mph S
Humidity39%
Visibility6.2 mi
Dew point32°
Tue, 2054° / 36°0
54 °
Portal, Tuesday, 20 October
Overcast. High 54°, low 36°.
Pressure30.09 inHg
Wind3.1 mph NE
Humidity60%
Visibility6.2 mi
Dew point36°
Wed, 2160° / 34°0
60 °
Portal, Wednesday, 21 October
Clear. High 60°, low 34°.
Pressure30.03 inHg
Wind6.1 mph S
Humidity45%
Visibility—
Dew point31°
Thu, 2259° / 38°0.19
59 °
Portal, Thursday, 22 October
Rain. High 59°, low 38°.
Pressure29.85 inHg
Wind8 mph S
Humidity49%
Visibility—
Dew point35°
Fri, 2346° / 33°0.17
46 °
Portal, Friday, 23 October
Snow. High 46°, low 33°.
Pressure29.74 inHg
Wind8.1 mph N
Humidity80%
Visibility—
Dew point40°
Sat, 2445° / 27°0.02
45 °
Portal, Saturday, 24 October
Light snow. High 45°, low 27°.
Pressure30.03 inHg
Wind4.9 mph S
Humidity75%
Visibility—
Dew point33°
Sun, 2546° / 35°0.01
46 °
Portal, Sunday, 25 October
Light rain. High 46°, low 35°.
Pressure29.74 inHg
Wind5.6 mph SE
Humidity62%
Visibility—
Dew point31°
Mon, 2639° / 31°0.51
39 °
Portal, Monday, 26 October
Snow. High 39°, low 31°.
Pressure29.71 inHg
Wind16 mph SW
Humidity74%
Visibility—
Dew point28°
Tue, 2739° / 30°0.1
39 °
Portal, Tuesday, 27 October
Snow. High 39°, low 30°.
Pressure29.62 inHg
Wind17.4 mph W
Humidity67%
Visibility—
Dew point28°
Wed, 2837° / 27°0
37 °
Portal, Wednesday, 28 October
Mostly clear. High 37°, low 27°.
Pressure30.00 inHg
Wind18.9 mph W
Humidity54%
Visibility—
Dew point19°
Thu, 2940° / 28°0.21
40 °
Portal, Thursday, 29 October
Snow. High 40°, low 28°.
Pressure29.62 inHg
Wind10.2 mph SW
Humidity52%
Visibility—
Dew point22°
Fri, 3029° / 14°0.48
29 °
Portal, Friday, 30 October
Snow. High 29°, low 14°.
Pressure29.94 inHg
Wind8.1 mph NW
Humidity88%
Visibility—
Dew point22°
Sat, 3132° / 12°0
32 °
Portal, Saturday, 31 October
Overcast. High 32°, low 12°.
Pressure29.80 inHg
Wind7.5 mph SW
Humidity70%
Visibility—
Dew point18°
Sun, 0135° / 16°0
35 °
Portal, Sunday, 1 November
Overcast. High 35°, low 16°.
Pressure29.85 inHg
Wind7.1 mph SW
Humidity79%
Visibility—
Dew point26°
From day 17 onward the outlook is built from 60-year climate statistics
Mon, 0246° / 28°0.04
46 °
Portal, Monday, 2 November
Climate normal for this date — 60-year average.
Average high46°
Average low28°
Average precipitation0.04 in
Chance of precipitation30%
Record high63° (1981)
Record low-14° (1991)
Tue, 0346° / 29°0.04
46 °
Portal, Tuesday, 3 November
Climate normal for this date — 60-year average.
Average high46°
Average low29°
Average precipitation0.04 in
Chance of precipitation22%
Record high65° (1962)
Record low-5° (1991)
Wed, 0446° / 29°0.06
46 °
Portal, Wednesday, 4 November
Climate normal for this date — 60-year average.
Average high46°
Average low29°
Average precipitation0.06 in
Chance of precipitation33%
Record high62° (1976)
Record low-3° (1973)
Thu, 0546° / 29°0.05
46 °
Portal, Thursday, 5 November
Climate normal for this date — 60-year average.
Average high46°
Average low29°
Average precipitation0.05 in
Chance of precipitation27%
Record high63° (1980)
Record low3° (1961)
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)
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.