As of 05:25 EDT

Weather in Herndon, PA

50°

Herndon, Saturday, 17 October, 05:25

Light rain. Feels like 49°. High 57°, low 38°.

Pressure30.03 inHg

Wind15 mph N

Humidity75%

Visibility6.2 mi

Dew point43°

See detailed hourly forecast

Sun, 1859° / 35°

59 °

Herndon, Sunday, 18 October

Clear. High 59°, low 35°.

Pressure30.59 inHg

Wind1.5 mph N

Humidity52%

Visibility6.2 mi

Dew point35°

Mon, 1965° / 39°

65 °

Herndon, Monday, 19 October

Clear. High 65°, low 39°.

Pressure30.45 inHg

Wind4.5 mph N

Humidity57%

Visibility6.2 mi

Dew point43°

Tue, 2064° / 48°

64 °

Herndon, Tuesday, 20 October

Clear. High 64°, low 48°.

Pressure30.30 inHg

Wind9.8 mph N

Humidity62%

Visibility6.2 mi

Dew point47°

Wed, 2160° / 42°

60 °

Herndon, Wednesday, 21 October

Clear. High 60°, low 42°.

Pressure30.33 inHg

Wind7.3 mph N

Humidity63%

Visibility—

Dew point39°

Thu, 2261° / 40°

61 °

Herndon, Thursday, 22 October

Clear. High 61°, low 40°.

Pressure30.15 inHg

Wind9.4 mph N

Humidity58%

Visibility—

Dew point38°

Fri, 2361° / 41°

61 °

Herndon, Friday, 23 October

Clear. High 61°, low 41°.

Pressure30.27 inHg

Wind11.6 mph N

Humidity60%

Visibility—

Dew point39°

Sat, 2461° / 38°

61 °

Herndon, Saturday, 24 October

Clear. High 61°, low 38°.

Pressure30.45 inHg

Wind3.8 mph NE

Humidity54%

Visibility—

Dew point35°

Sun, 2562° / 39°

62 °

Herndon, Sunday, 25 October

Partly cloudy. High 62°, low 39°.

Pressure30.30 inHg

Wind3.5 mph W

Humidity54%

Visibility—

Dew point36°

Mon, 2666° / 43°

66 °

Herndon, Monday, 26 October

Overcast. High 66°, low 43°.

Pressure30.12 inHg

Wind5.6 mph SW

Humidity56%

Visibility—

Dew point41°

Tue, 2754° / 39°

0.02

54 °

Herndon, Tuesday, 27 October

Light rain. High 54°, low 39°.

Pressure30.12 inHg

Wind17 mph NW

Humidity65%

Visibility—

Dew point40°

Wed, 2849° / 34°

49 °

Herndon, Wednesday, 28 October

Overcast. High 49°, low 34°.

Pressure30.47 inHg

Wind6.7 mph N

Humidity51%

Visibility—

Dew point26°

Thu, 2955° / 41°

0.04

55 °

Herndon, Thursday, 29 October

Light rain. High 55°, low 41°.

Pressure30.00 inHg

Wind14.5 mph W

Humidity79%

Visibility—

Dew point36°

Fri, 3052° / 39°

0.01

52 °

Herndon, Friday, 30 October

Light rain. High 52°, low 39°.

Pressure29.97 inHg

Wind17.1 mph NW

Humidity64%

Visibility—

Dew point38°

Sat, 3157° / 35°

57 °

Herndon, Saturday, 31 October

Clear. High 57°, low 35°.

Pressure30.27 inHg

Wind6 mph S

Humidity59%

Visibility—

Dew point33°

Sun, 0161° / 41°

61 °

Herndon, Sunday, 1 November

Overcast. High 61°, low 41°.

Pressure30.24 inHg

Wind10.7 mph S

Humidity76%

Visibility—

Dew point43°

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.