Monthly outlook for Walnut, CA: average high 91.4°, average low 71.9°. That is 1.5° above the climate normal for August. Precipitation is expected on 0 days (about 0.0 inches), against a normal of 0 days and 0.1 inches. The warmest day looks like 9 August (95.8°), the coolest 8 August (67.8°).
91.4°/71.9°
Average high / low
+1.5°
Above normal
0 / 0
Wet days / normal
0.0 in
Precipitation this month
Ten-day blocks vs climate normal
Period
Forecast high
Normal
Difference
8 August – 17 August
90.8°
89.1°
+0.9°
18 August – 27 August
92.4°
88.8°
+2°
28 August – 6 September
at normal
90.5°
—
August records over 66 years
108.7°18 August 2020All-time high
53.4°22 August 1968All-time low
Climate normals and records are computed from the nearest reference point — South San Jose Hills (3 mi).
Sun, 0996° / 70°0
96 °
Walnut, Sunday, 9 August
Clear. High 96°, low 70°.
Pressure29.83 inHg
Wind7.9 mph SW
Humidity28%
Visibility6.2 mi
Dew point54°
Mon, 1092° / 70°0
92 °
Walnut, Monday, 10 August
Overcast. High 92°, low 70°.
Pressure29.91 inHg
Wind8.2 mph SW
Humidity29%
Visibility6.2 mi
Dew point54°
Tue, 1189° / 73°0
89 °
Walnut, Tuesday, 11 August
Overcast. High 89°, low 73°.
Pressure29.97 inHg
Wind8.5 mph SW
Humidity30%
Visibility6.2 mi
Dew point52°
Wed, 1289° / 72°0
89 °
Walnut, Wednesday, 12 August
Overcast. High 89°, low 72°.
Pressure29.91 inHg
Wind11.6 mph SW
Humidity35%
Visibility—
Dew point51°
Thu, 1386° / 69°0
86 °
Walnut, Thursday, 13 August
Overcast. High 86°, low 69°.
Pressure29.91 inHg
Wind10.4 mph SW
Humidity44%
Visibility—
Dew point54°
Fri, 1486° / 68°0
86 °
Walnut, Friday, 14 August
Overcast. High 86°, low 68°.
Pressure29.97 inHg
Wind10 mph SW
Humidity43%
Visibility—
Dew point53°
Sat, 1591° / 70°0
91 °
Walnut, Saturday, 15 August
Partly cloudy. High 91°, low 70°.
Pressure30.00 inHg
Wind10.2 mph SW
Humidity34%
Visibility—
Dew point51°
Sun, 1692° / 73°0
92 °
Walnut, Sunday, 16 August
Mostly clear. High 92°, low 73°.
Pressure30.00 inHg
Wind11.4 mph SW
Humidity33%
Visibility—
Dew point51°
Mon, 1793° / 72°0
93 °
Walnut, Monday, 17 August
Mostly clear. High 93°, low 72°.
Pressure30.03 inHg
Wind10.5 mph SW
Humidity31%
Visibility—
Dew point49°
Tue, 1891° / 72°0
91 °
Walnut, Tuesday, 18 August
Clear. High 91°, low 72°.
Pressure29.94 inHg
Wind9.8 mph SW
Humidity37%
Visibility—
Dew point54°
Wed, 1987° / 73°0
87 °
Walnut, Wednesday, 19 August
Overcast. High 87°, low 73°.
Pressure29.88 inHg
Wind10.2 mph SW
Humidity38%
Visibility—
Dew point55°
Thu, 2093° / 73°0
93 °
Walnut, Thursday, 20 August
Clear. High 93°, low 73°.
Pressure29.88 inHg
Wind10.6 mph SW
Humidity36%
Visibility—
Dew point55°
Fri, 2194° / 75°0
94 °
Walnut, Friday, 21 August
Overcast. High 94°, low 75°.
Pressure29.94 inHg
Wind9.8 mph SW
Humidity32%
Visibility—
Dew point52°
Sat, 2296° / 75°0
96 °
Walnut, Saturday, 22 August
Mostly clear. High 96°, low 75°.
Pressure29.94 inHg
Wind11 mph SW
Humidity27%
Visibility—
Dew point49°
Sun, 2393° / 76°0
93 °
Walnut, Sunday, 23 August
Overcast. High 93°, low 76°.
Pressure29.91 inHg
Wind10.1 mph SW
Humidity29%
Visibility—
Dew point49°
From day 17 onward the outlook is built from 60-year climate statistics
Mon, 2489° / 65°0
89 °
Walnut, Monday, 24 August
Climate normal for this date — 60-year average.
Average high89°
Average low65°
Average precipitation0 in
Chance of precipitation0%
Record high102° (1985)
Record low58° (1978)
Tue, 2590° / 65°0
90 °
Walnut, Tuesday, 25 August
Climate normal for this date — 60-year average.
Average high90°
Average low65°
Average precipitation0 in
Chance of precipitation2%
Record high105° (1985)
Record low58° (1978)
Wed, 2690° / 66°0
90 °
Walnut, Wednesday, 26 August
Climate normal for this date — 60-year average.
Average high90°
Average low66°
Average precipitation0 in
Chance of precipitation2%
Record high105° (1981)
Record low58° (1990)
Thu, 2791° / 65°0
91 °
Walnut, Thursday, 27 August
Climate normal for this date — 60-year average.
Average high91°
Average low65°
Average precipitation0 in
Chance of precipitation0%
Record high105° (1981)
Record low57° (1973)
Fri, 2892° / 66°0
92 °
Walnut, Friday, 28 August
Climate normal for this date — 60-year average.
Average high92°
Average low66°
Average precipitation0 in
Chance of precipitation0%
Record high104° (1981)
Record low58° (1973)
Sat, 2992° / 67°0
92 °
Walnut, Saturday, 29 August
Climate normal for this date — 60-year average.
Average high92°
Average low67°
Average precipitation0 in
Chance of precipitation2%
Record high104° (1967)
Record low58° (2010)
Sun, 3091° / 67°0
91 °
Walnut, Sunday, 30 August
Climate normal for this date — 60-year average.
Average high91°
Average low67°
Average precipitation0 in
Chance of precipitation0%
Record high105° (2017)
Record low58° (2024)
Mon, 3190° / 66°0
90 °
Walnut, Monday, 31 August
Climate normal for this date — 60-year average.
Average high90°
Average low66°
Average precipitation0 in
Chance of precipitation2%
Record high107° (2017)
Record low58° (1992)
Tue, 0190° / 65°0.03
90 °
Walnut, Tuesday, 1 September
Climate normal for this date — 60-year average.
Average high90°
Average low65°
Average precipitation0.03 in
Chance of precipitation3%
Record high106° (2017)
Record low57° (1964)
Wed, 0290° / 66°0.04
90 °
Walnut, Wednesday, 2 September
Climate normal for this date — 60-year average.
Average high90°
Average low66°
Average precipitation0.04 in
Chance of precipitation5%
Record high105° (1982)
Record low54° (1964)
Thu, 0390° / 66°0.01
90 °
Walnut, Thursday, 3 September
Climate normal for this date — 60-year average.
Average high90°
Average low66°
Average precipitation0.01 in
Chance of precipitation5%
Record high108° (1988)
Record low57° (1964)
Fri, 0491° / 66°0
91 °
Walnut, Friday, 4 September
Climate normal for this date — 60-year average.
Average high91°
Average low66°
Average precipitation0 in
Chance of precipitation2%
Record high111° (2022)
Record low58° (1964)
Sat, 0591° / 66°0.01
91 °
Walnut, Saturday, 5 September
Climate normal for this date — 60-year average.
Average high91°
Average low66°
Average precipitation0.01 in
Chance of precipitation3%
Record high116° (2020)
Record low57° (1970)
Sun, 0691° / 66°0.01
91 °
Walnut, Sunday, 6 September
Climate normal for this date — 60-year average.
Average high91°
Average low66°
Average precipitation0.01 in
Chance of precipitation3%
Record high117° (2024)
Record low57° (1970)
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 Walnut, CA 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 Walnut, CA 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.