As of 20:29 EDT

Weather in Herndon, PA

58°

Herndon, Sunday, 11 October, 20:29

Overcast. Feels like 58°. High 60°, low 56°.

Pressure29.88 inHg

Wind8.1 mph N

Humidity97%

Visibility2.4 mi

Dew point57°

See detailed hourly forecast

Mon, 1273° / 53°

73 °

Herndon, Monday, 12 October

Partly cloudy. High 73°, low 53°.

Pressure29.88 inHg

Wind6.6 mph N

Humidity67%

Visibility6.2 mi

Dew point57°

Tue, 1379° / 53°

79 °

Herndon, Tuesday, 13 October

Clear. High 79°, low 53°.

Pressure29.88 inHg

Wind8 mph SW

Humidity70%

Visibility6.2 mi

Dew point63°

Wed, 1478° / 59°

78 °

Herndon, Wednesday, 14 October

Partly cloudy. High 78°, low 59°.

Pressure29.91 inHg

Wind9.3 mph W

Humidity64%

Visibility6.2 mi

Dew point61°

Thu, 1564° / 54°

64 °

Herndon, Thursday, 15 October

Overcast. High 64°, low 54°.

Pressure30.21 inHg

Wind4.5 mph NE

Humidity63%

Visibility6.2 mi

Dew point49°

Fri, 1668° / 51°

0.44

68 °

Herndon, Friday, 16 October

Rain. High 68°, low 51°.

Pressure29.62 inHg

Wind18.6 mph NW

Humidity96%

Visibility—

Dew point65°

Sat, 1747° / 34°

47 °

Herndon, Saturday, 17 October

Mostly clear. High 47°, low 34°.

Pressure30.24 inHg

Wind18.5 mph NW

Humidity47%

Visibility—

Dew point24°

Sun, 1851° / 29°

51 °

Herndon, Sunday, 18 October

Clear. High 51°, low 29°.

Pressure30.65 inHg

Wind9.1 mph NW

Humidity46%

Visibility—

Dew point22°

Mon, 1960° / 32°

60 °

Herndon, Monday, 19 October

Clear. High 60°, low 32°.

Pressure30.59 inHg

Wind8 mph SW

Humidity48%

Visibility—

Dew point28°

Tue, 2063° / 39°

63 °

Herndon, Tuesday, 20 October

Clear. High 63°, low 39°.

Pressure30.47 inHg

Wind2.8 mph NW

Humidity56%

Visibility—

Dew point38°

Wed, 2163° / 45°

63 °

Herndon, Wednesday, 21 October

Overcast. High 63°, low 45°.

Pressure30.59 inHg

Wind10.9 mph SE

Humidity69%

Visibility—

Dew point46°

Thu, 2261° / 52°

61 °

Herndon, Thursday, 22 October

Overcast. High 61°, low 52°.

Pressure30.62 inHg

Wind8.9 mph SE

Humidity72%

Visibility—

Dew point46°

Fri, 2365° / 49°

65 °

Herndon, Friday, 23 October

Overcast. High 65°, low 49°.

Pressure30.47 inHg

Wind6.7 mph S

Humidity70%

Visibility—

Dew point49°

Sat, 2468° / 51°

68 °

Herndon, Saturday, 24 October

Overcast. High 68°, low 51°.

Pressure30.21 inHg

Wind9.7 mph S

Humidity86%

Visibility—

Dew point55°

Sun, 2572° / 54°

0.1

72 °

Herndon, Sunday, 25 October

Light rain. High 72°, low 54°.

Pressure29.91 inHg

Wind9.4 mph NW

Humidity73%

Visibility—

Dew point55°

Mon, 2658° / 42°

58 °

Herndon, Monday, 26 October

Overcast. High 58°, low 42°.

Pressure29.97 inHg

Wind7.9 mph NW

Humidity65%

Visibility—

Dew point40°

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 Herndon, PA 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 Herndon, PA 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.