Monthly outlook for Duncan, WA: average high 88.4°, average low 60.5°. That is 2.3° above the climate normal for August. Precipitation is expected on 0 days (about 0.0 inches), against a normal of 2 days and 0.4 inches. The warmest day looks like 23 August (101.4°), the coolest 10 August (53.4°).
88.4°/60.5°
Average high / low
+2.3°
Above normal
0 / 2
Wet days / normal
0.0 in
Precipitation this month
Ten-day blocks vs climate normal
Period
Forecast high
Normal
Difference
8 August – 17 August
86.5°
85.4°
+0.6°
18 August – 27 August
91.5°
81.7°
+5.4°
28 August – 6 September
at normal
79.5°
—
August records over 66 years
107.1°4 August 1961All-time high
42.4°31 August 1964All-time low
Climate normals and records are computed from the nearest reference point — Spokane (12 mi).
Sun, 0987° / 54°0
87 °
Duncan, Sunday, 9 August
Clear. High 87°, low 54°.
Pressure29.88 inHg
Wind9.9 mph SW
Humidity16%
Visibility6.2 mi
Dew point34°
Mon, 1087° / 53°0
87 °
Duncan, Monday, 10 August
Clear. High 87°, low 53°.
Pressure29.91 inHg
Wind10.4 mph SW
Humidity23%
Visibility6.2 mi
Dew point39°
Tue, 1188° / 61°0
88 °
Duncan, Tuesday, 11 August
Clear. High 88°, low 61°.
Pressure29.94 inHg
Wind10.9 mph SW
Humidity20%
Visibility6.2 mi
Dew point38°
Wed, 1286° / 60°0
86 °
Duncan, Wednesday, 12 August
Clear. High 86°, low 60°.
Pressure29.85 inHg
Wind9.5 mph SW
Humidity29%
Visibility6.2 mi
Dew point46°
Thu, 1382° / 57°0
82 °
Duncan, Thursday, 13 August
Clear. High 82°, low 57°.
Pressure29.85 inHg
Wind10.4 mph SW
Humidity34%
Visibility—
Dew point42°
Fri, 1488° / 59°0
88 °
Duncan, Friday, 14 August
Clear. High 88°, low 59°.
Pressure29.91 inHg
Wind5.3 mph NW
Humidity20%
Visibility—
Dew point34°
Sat, 1581° / 63°0
81 °
Duncan, Saturday, 15 August
Overcast. High 81°, low 63°.
Pressure29.91 inHg
Wind20.7 mph SW
Humidity17%
Visibility—
Dew point30°
Sun, 1687° / 57°0.01
87 °
Duncan, Sunday, 16 August
Light rain. High 87°, low 57°.
Pressure29.97 inHg
Wind11.5 mph W
Humidity23%
Visibility—
Dew point38°
Mon, 1792° / 62°0
92 °
Duncan, Monday, 17 August
Clear. High 92°, low 62°.
Pressure29.97 inHg
Wind9.4 mph SW
Humidity19%
Visibility—
Dew point36°
Tue, 1881° / 63°0
81 °
Duncan, Tuesday, 18 August
Overcast. High 81°, low 63°.
Pressure30.00 inHg
Wind18.5 mph SW
Humidity24%
Visibility—
Dew point39°
Wed, 1992° / 58°0
92 °
Duncan, Wednesday, 19 August
Overcast. High 92°, low 58°.
Pressure30.00 inHg
Wind7.5 mph NW
Humidity29%
Visibility—
Dew point42°
Thu, 2090° / 65°0.01
90 °
Duncan, Thursday, 20 August
Light rain. High 90°, low 65°.
Pressure29.91 inHg
Wind9.9 mph SW
Humidity22%
Visibility—
Dew point38°
Fri, 2190° / 64°0
90 °
Duncan, Friday, 21 August
Mostly clear. High 90°, low 64°.
Pressure29.97 inHg
Wind10 mph SW
Humidity27%
Visibility—
Dew point43°
Sat, 2294° / 67°0
94 °
Duncan, Saturday, 22 August
Clear. High 94°, low 67°.
Pressure29.94 inHg
Wind6.1 mph S
Humidity25%
Visibility—
Dew point43°
Sun, 23101° / 67°0.02
101 °
Duncan, Sunday, 23 August
Light rain. High 101°, low 67°.
Pressure29.85 inHg
Wind6.6 mph NE
Humidity16%
Visibility—
Dew point36°
From day 17 onward the outlook is built from 60-year climate statistics
Mon, 2480° / 57°0.05
80 °
Duncan, Monday, 24 August
Climate normal for this date — 60-year average.
Average high80°
Average low57°
Average precipitation0.05 in
Chance of precipitation13%
Record high98° (1966)
Record low44° (2021)
Tue, 2580° / 56°0.03
80 °
Duncan, Tuesday, 25 August
Climate normal for this date — 60-year average.
Average high80°
Average low56°
Average precipitation0.03 in
Chance of precipitation10%
Record high95° (1996)
Record low43° (1992)
Wed, 2682° / 56°0.02
82 °
Duncan, Wednesday, 26 August
Climate normal for this date — 60-year average.
Average high82°
Average low56°
Average precipitation0.02 in
Chance of precipitation10%
Record high97° (1996)
Record low47° (1976)
Thu, 2781° / 57°0.02
81 °
Duncan, Thursday, 27 August
Climate normal for this date — 60-year average.
Average high81°
Average low57°
Average precipitation0.02 in
Chance of precipitation12%
Record high95° (1986)
Record low43° (1960)
Fri, 2881° / 56°0.02
81 °
Duncan, Friday, 28 August
Climate normal for this date — 60-year average.
Average high81°
Average low56°
Average precipitation0.02 in
Chance of precipitation10%
Record high99° (2009)
Record low44° (1960)
Sat, 2982° / 57°0.01
82 °
Duncan, Saturday, 29 August
Climate normal for this date — 60-year average.
Average high82°
Average low57°
Average precipitation0.01 in
Chance of precipitation13%
Record high96° (2017)
Record low43° (1965)
Sun, 3080° / 56°0.03
80 °
Duncan, Sunday, 30 August
Climate normal for this date — 60-year average.
Average high80°
Average low56°
Average precipitation0.03 in
Chance of precipitation12%
Record high95° (1967)
Record low45° (1965)
Mon, 3179° / 56°0.02
79 °
Duncan, Monday, 31 August
Climate normal for this date — 60-year average.
Average high79°
Average low56°
Average precipitation0.02 in
Chance of precipitation17%
Record high103° (2022)
Record low42° (1964)
Tue, 0179° / 56°0.02
79 °
Duncan, Tuesday, 1 September
Climate normal for this date — 60-year average.
Average high79°
Average low56°
Average precipitation0.02 in
Chance of precipitation10%
Record high97° (2025)
Record low45° (2021)
Wed, 0279° / 55°0.02
79 °
Duncan, Wednesday, 2 September
Climate normal for this date — 60-year average.
Average high79°
Average low55°
Average precipitation0.02 in
Chance of precipitation10%
Record high100° (2025)
Record low44° (1999)
Thu, 0379° / 55°0.02
79 °
Duncan, Thursday, 3 September
Climate normal for this date — 60-year average.
Average high79°
Average low55°
Average precipitation0.02 in
Chance of precipitation13%
Record high101° (1988)
Record low43° (1980)
Fri, 0480° / 55°0.01
80 °
Duncan, Friday, 4 September
Climate normal for this date — 60-year average.
Average high80°
Average low55°
Average precipitation0.01 in
Chance of precipitation12%
Record high99° (1988)
Record low45° (1965)
Sat, 0579° / 55°0.02
79 °
Duncan, Saturday, 5 September
Climate normal for this date — 60-year average.
Average high79°
Average low55°
Average precipitation0.02 in
Chance of precipitation7%
Record high96° (1988)
Record low44° (1969)
Sun, 0678° / 54°0.02
78 °
Duncan, Sunday, 6 September
Climate normal for this date — 60-year average.
Average high78°
Average low54°
Average precipitation0.02 in
Chance of precipitation15%
Record high95° (2024)
Record low41° (1960)
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 Duncan, WA 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 Duncan, WA 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.