As of 14:27 EDT

Weather in Herndon, PA

66°

Herndon, Thursday, 15 October, 14:27

Clear. Feels like 65°. High 66°, low 54°.

Pressure30.15 inHg

Wind2 mph E

Humidity66%

Visibility6.2 mi

Dew point55°

See detailed hourly forecast

Fri, 1680° / 59°

0.33

80 °

Herndon, Friday, 16 October

Heavy rain. High 80°, low 59°.

Pressure29.71 inHg

Wind13 mph S

Humidity77%

Visibility6.2 mi

Dew point65°

Sat, 1760° / 41°

60 °

Herndon, Saturday, 17 October

Light rain. High 60°, low 41°.

Pressure30.27 inHg

Wind14.5 mph N

Humidity49%

Visibility6.2 mi

Dew point28°

Sun, 1858° / 36°

58 °

Herndon, Sunday, 18 October

Clear. High 58°, low 36°.

Pressure30.59 inHg

Wind3.3 mph SW

Humidity57%

Visibility6.2 mi

Dew point40°

Mon, 1961° / 40°

61 °

Herndon, Monday, 19 October

Clear. High 61°, low 40°.

Pressure30.53 inHg

Wind4.5 mph S

Humidity55%

Visibility6.2 mi

Dew point40°

Tue, 2063° / 40°

63 °

Herndon, Tuesday, 20 October

Partly cloudy. High 63°, low 40°.

Pressure30.39 inHg

Wind2.6 mph N

Humidity69%

Visibility—

Dew point42°

Wed, 2164° / 45°

64 °

Herndon, Wednesday, 21 October

Partly cloudy. High 64°, low 45°.

Pressure30.36 inHg

Wind6.9 mph N

Humidity65%

Visibility—

Dew point45°

Thu, 2262° / 41°

62 °

Herndon, Thursday, 22 October

Clear. High 62°, low 41°.

Pressure30.39 inHg

Wind3.6 mph SW

Humidity61%

Visibility—

Dew point40°

Fri, 2360° / 40°

60 °

Herndon, Friday, 23 October

Clear. High 60°, low 40°.

Pressure30.39 inHg

Wind12.3 mph N

Humidity48%

Visibility—

Dew point34°

Sat, 2454° / 33°

54 °

Herndon, Saturday, 24 October

Partly cloudy. High 54°, low 33°.

Pressure30.65 inHg

Wind4.8 mph E

Humidity54%

Visibility—

Dew point28°

Sun, 2554° / 33°

54 °

Herndon, Sunday, 25 October

Overcast. High 54°, low 33°.

Pressure30.53 inHg

Wind3.4 mph NE

Humidity43%

Visibility—

Dew point24°

Mon, 2661° / 37°

61 °

Herndon, Monday, 26 October

Clear. High 61°, low 37°.

Pressure30.47 inHg

Wind12.1 mph N

Humidity55%

Visibility—

Dew point36°

Tue, 2758° / 36°

58 °

Herndon, Tuesday, 27 October

Overcast. High 58°, low 36°.

Pressure30.42 inHg

Wind6.6 mph SW

Humidity60%

Visibility—

Dew point34°

Wed, 2857° / 49°

0.04

57 °

Herndon, Wednesday, 28 October

Light rain. High 57°, low 49°.

Pressure30.18 inHg

Wind9.4 mph N

Humidity88%

Visibility—

Dew point53°

Thu, 2949° / 43°

0.07

49 °

Herndon, Thursday, 29 October

Light rain. High 49°, low 43°.

Pressure30.36 inHg

Wind6.1 mph S

Humidity91%

Visibility—

Dew point42°

Fri, 3061° / 49°

0.16

61 °

Herndon, Friday, 30 October

Light rain. High 61°, low 49°.

Pressure30.15 inHg

Wind5.9 mph SW

Humidity84%

Visibility—

Dew point51°

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.