Monthly outlook for Portal, MT: average high 47°, average low 27°. That is 1.8° below the climate normal for October. Precipitation is expected on 3 days (about 0.7 inches), against a normal of 4 days and 0.7 inches. The warmest day looks like 19 October (67.4°), the coolest 30 October (6.3°).
47°/27°
Average high / low
−1.8°
Below normal
3 / 4
Wet days / normal
0.7 in
Precipitation this month
Ten-day blocks vs climate normal
Period
Forecast high
Normal
Difference
18 October – 27 October
52.5°
52.7°
-0.1°
28 October – 6 November
37.9°
46°
-4.5°
7 November – 16 November
at normal
41.8°
—
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).
Mon, 1967° / 33°0
67 °
Portal, Monday, 19 October
Overcast. High 67°, low 33°.
Pressure29.94 inHg
Wind6.4 mph S
Humidity38%
Visibility6.2 mi
Dew point30°
Tue, 2053° / 34°0
53 °
Portal, Tuesday, 20 October
Overcast. High 53°, low 34°.
Pressure30.09 inHg
Wind4 mph NE
Humidity52%
Visibility6.2 mi
Dew point34°
Wed, 2158° / 33°0
58 °
Portal, Wednesday, 21 October
Mostly clear. High 58°, low 33°.
Pressure30.06 inHg
Wind5.7 mph S
Humidity48%
Visibility6.2 mi
Dew point36°
Thu, 2260° / 39°0.02
60 °
Portal, Thursday, 22 October
Light rain. High 60°, low 39°.
Pressure29.80 inHg
Wind12 mph S
Humidity53%
Visibility—
Dew point35°
Fri, 2343° / 29°0.1
43 °
Portal, Friday, 23 October
Light rain. High 43°, low 29°.
Pressure29.80 inHg
Wind14.7 mph W
Humidity76%
Visibility—
Dew point30°
Sat, 2448° / 25°0
48 °
Portal, Saturday, 24 October
Overcast. High 48°, low 25°.
Pressure30.27 inHg
Wind4.9 mph SW
Humidity46%
Visibility—
Dew point21°
Sun, 2555° / 35°0
55 °
Portal, Sunday, 25 October
Overcast. High 55°, low 35°.
Pressure30.00 inHg
Wind5.6 mph SW
Humidity33%
Visibility—
Dew point22°
Mon, 2642° / 29°0
42 °
Portal, Monday, 26 October
Overcast. High 42°, low 29°.
Pressure30.03 inHg
Wind5.9 mph NE
Humidity69%
Visibility—
Dew point27°
Tue, 2736° / 29°0.41
36 °
Portal, Tuesday, 27 October
Snow. High 36°, low 29°.
Pressure29.77 inHg
Wind11.8 mph W
Humidity85%
Visibility—
Dew point31°
Wed, 2841° / 25°0.02
41 °
Portal, Wednesday, 28 October
Light snow. High 41°, low 25°.
Pressure29.80 inHg
Wind19.3 mph W
Humidity46%
Visibility—
Dew point19°
Thu, 2929° / 15°0.13
29 °
Portal, Thursday, 29 October
Snow. High 29°, low 15°.
Pressure29.83 inHg
Wind8.6 mph N
Humidity84%
Visibility—
Dew point25°
Fri, 3030° / 6°0
30 °
Portal, Friday, 30 October
Light snow. High 30°, low 6°.
Pressure30.24 inHg
Wind8.9 mph W
Humidity51%
Visibility—
Dew point8°
Sat, 3139° / 15°0
39 °
Portal, Saturday, 31 October
Mostly clear. High 39°, low 15°.
Pressure30.03 inHg
Wind6.4 mph SW
Humidity44%
Visibility—
Dew point14°
Sun, 0141° / 20°0.01
41 °
Portal, Sunday, 1 November
Light snow. High 41°, low 20°.
Pressure29.94 inHg
Wind6.4 mph SW
Humidity52%
Visibility—
Dew point19°
Mon, 0247° / 29°0.02
47 °
Portal, Monday, 2 November
Light snow. High 47°, low 29°.
Pressure29.77 inHg
Wind17.5 mph SW
Humidity66%
Visibility—
Dew point33°
From day 17 onward the outlook is built from 60-year climate statistics
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)
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)
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.