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Contents
- Weather in January
- Weather in February
- Weather in March
- Weather in April
- Weather in May
- Weather in June
- Weather in July
- Weather in August
- Weather in September
- Weather in October
- Weather in November
- Weather in December
- Frequently asked questions
- Average temperature
- Average pressure
- Average wind speed
- Average humidity
- Average rainfall
- Average rainfall days
- Average snowfall
- Average snowfall days
- Average daylight
- Average sunshine
- Average sunshine days
- Average UV index
- Average cloud cover
- Average visibility
Weather in January
January, like December, is another subzero cold winter month in Herndon, Iowa, with an average temperature varying between 26.8°F (-2.9°C) and 13.5°F (-10.3°C). The coldest temperatures occur during January, when averages reach a peak of 26.8°F (-2.9°C) and a low of 13.5°F (-10.3°C). Weather in January »
Weather in February
February, the last month of the winter in Herndon, is also a subzero cold month, with an average temperature ranging between max 30.6°F (-0.8°C) and min 16.9°F (-8.4°C). February experiences an average high-temperature of a still subzero cold 30.6°F (-0.8°C), barely different from January's 26.8°F (-2.9°C). Weather in February »
Weather in March
March, the first month of the spring in Herndon, is a chilly month, with an average temperature fluctuating between 46°F (7.8°C) and 31.1°F (-0.5°C). March is marked by a significant increase, with the average high-temperature advancing from a subzero cold 30.6°F (-0.8°C) in February to a frosty 46°F (7.8°C). Weather in March »
Weather in April
April in Herndon, Iowa, is a mild spring month, with an average temperature varying between 42.1°F (5.6°C) and 58.5°F (14.7°C). April indicates a change in the average high-temperature, moving up from a frosty 46°F (7.8°C) in March to a mild 58.5°F (14.7°C). Weather in April »
Weather in May
May, the last month of the spring in Herndon, is a pleasant month, with an average temperature fluctuating between 69.4°F (20.8°C) and 53.1°F (11.7°C). Herndon sees an increase in average high-temperatures during May, moving from a mild 58.5°F (14.7°C) in April to a pleasant 69.4°F (20.8°C). Weather in May »
Weather in June
The first month of the summer, June, is a warm month in Herndon, Iowa, with an average temperature varying between 79.3°F (26.3°C) and 62.8°F (17.1°C). The start of June brings a shift in the average high-temperature, increasing from May's pleasant 69.4°F (20.8°C) to a warm 79.3°F (26.3°C). Weather in June »
Weather in July
July, like June, in Herndon, Iowa, is another warm summer month, with an average temperature varying between 82°F (27.8°C) and 64.6°F (18.1°C). July is the warmest month, exhibiting average temperatures of 82°F (27.8°C) at the peak and 64.6°F (18.1°C) at the base. Throughout July, the heat index is appraised at a hot 89.6°F (32°C). Weather in July »
Weather in August
The last month of the summer, August, is another warm month in Herndon, Iowa, with temperature in the range of an average high of 80.1°F (26.7°C) and an average low of 61.5°F (16.4°C). The commencement of August introduces an average high-temperature of a still moderately hot 80.1°F (26.7°C), closely mirroring the preceding month. Weather in August »
Weather in September
The first month of the autumn, September, is also a moderately hot month in Herndon, Iowa, with an average temperature fluctuating between 74.8°F (23.8°C) and 55.8°F (13.2°C). As September takes hold, the average high-temperature is a still warm 74.8°F (23.8°C), nearly mirroring that of the previous month. Weather in September »
Weather in October
October, like September, is another refreshing autumn month in Herndon, Iowa, with an average temperature ranging between min 43.9°F (6.6°C) and max 59.9°F (15.5°C). In October, the average high-temperature decreases considerably from a moderately hot 74.8°F (23.8°C) in September to a refreshing 59.9°F (15.5°C). Weather in October »
Weather in November
November, the last month of the autumn in Herndon, is also a frosty month, with temperature in the range of an average low of 32.5°F (0.3°C) and an average high of 45.9°F (7.7°C). The onset of November entails a temperature shift, as the average high-temperature decreases from a moderate 59.9°F (15.5°C) in October to a chilly 45.9°F (7.7°C). Weather in November »
Weather in December
December, the first month of the winter in Herndon, is still a cold month, with an average temperature varying between 32°F (0°C) and 21°F (-6.1°C). As November transitions to December, the average high-temperature falls from a chilly 45.9°F (7.7°C) to an icy 32°F (0°C). Weather in December »
Updated: Jun 19, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What is the coldest month?
Herndon's coldest weather arrives in January, when temperatures average a high of 26.8°F (-2.9°C) and a low of 13.5°F (-10.3°C).
What is the most humid month?
The most humid month is January, with an average relative humidity of 84%.
What is the driest month in Herndon?
The month with the least rainfall is January, when the rain falls for 3.8 days and typically collects 0.87" (22mm) of precipitation.
How much does it rain?
In Herndon, during the entire year, the rain falls for 125.7 days and collects up to 26.5" (673mm) of precipitation.
When does it snow?
January through May, October through December are months with snowfall.
When does it snow the most in Herndon?
January is the month with the most snowfall. Snow falls for 9.8 days and accumulates 4.29" (109mm) of snow.
How many days does it snow?
In Herndon, during the entire year, snow falls for 38.1 days and aggregates up to 15.31" (389mm) of snow.
What is the month with the least sunshine?
January has the least sunshine of the year, with an average of 4.2h of sunshine.
When is the lowest UV index?
January, February, October through December, with an average maximum UV index of 2, are months with the lowest UV index.
When is Daylight Saving Time (DST)?
On Sunday, March 10. 2024, at 2:00 am, Daylight Saving Time starts, and the time zone changes from CST to CDT. Daylight Saving Time ends Sunday, November 3. 2024, at 2:00 am, and the time zone reverts from CDT to CST.
What is the rainiest month?
The month with the most rainfall is May, when the rain falls for 16.2 days and typically aggregates up to 4.06" (103mm) of precipitation.
When it does not snow?
In Herndon, snow does not fall in June through September.
When are the longest days?
June has the longest days of the year, with an average of 15h and 12min of daylight.
What are the months with the highest UV index?
The months with the highest UV index are June and July, with an average maximum UV index of 6.
What is the warmest month?
Temperature records mark July as the warmest month, with highs averaging 82°F (27.8°C) and lows at 64.6°F (18.1°C).
What month has the most sunshine in Herndon?
With an average of 10.2h of sunshine, July has the most sunshine of the year.
What is the least humid month?
The least humid month is October, with an average relative humidity of 69%.
What is the month with the shortest days?
December has the shortest days of the year, with an average of 9h and 12min of daylight.
Average temperature
Herndon, IA
The warmest month (with the highest average high temperature) is July (82°F).
The month with the lowest average high temperature is January (26.8°F).
The month with the highest average low temperature is July (64.6°F).
The coldest month (with the lowest average low temperature) is January (13.5°F).
Average pressure
Herndon, IA
- Average pressure in January:
30.16"Hg - Average pressure in February:
30.14"Hg - Average pressure in March:
30.07"Hg - Average pressure in April:
29.93"Hg - Average pressure in May:
29.93"Hg - Average pressure in June:
29.88"Hg
- Average pressure in July:
29.96"Hg - Average pressure in August:
29.96"Hg - Average pressure in September:
30.01"Hg - Average pressure in October:
30"Hg - Average pressure in November:
30.08"Hg - Average pressure in December:
30.12"Hg
The month with the highest atmospheric pressure is January (30.16"Hg).
The month with the lowest atmospheric pressure is June (29.88"Hg).
Average wind speed
Herndon, IA
- Average wind speed in January:
10.6mph - Average wind speed in February:
10.5mph - Average wind speed in March:
10.4mph - Average wind speed in April:
10.7mph - Average wind speed in May:
9.1mph - Average wind speed in June:
8.3mph
- Average wind speed in July:
7.1mph - Average wind speed in August:
7.1mph - Average wind speed in September:
8.3mph - Average wind speed in October:
9.6mph - Average wind speed in November:
10.4mph - Average wind speed in December:
10.2mph
The windiest month (with the highest average wind speed) is April (10.7mph).
The calmest months (with the lowest average wind speed) are July and August (7.1mph).
Average humidity
Herndon, IA
The month with the highest relative humidity is January (84%).
The month with the lowest relative humidity is October (69%).
Average rainfall
Herndon, IA
- Average rainfall in January:
0.87" - Average rainfall in February:
1.02" - Average rainfall in March:
1.54" - Average rainfall in April:
2.76" - Average rainfall in May:
4.06" - Average rainfall in June:
3.94"
- Average rainfall in July:
2.28" - Average rainfall in August:
2.44" - Average rainfall in September:
2.91" - Average rainfall in October:
2.2" - Average rainfall in November:
1.14" - Average rainfall in December:
1.34"
The wettest month (with the highest rainfall) is May (4.06").
The driest month (with the least rainfall) is January (0.87").
Average rainfall days
Herndon, IA
- Average rainfall days in January:
3.8 days - Average rainfall days in February:
3.4 days - Average rainfall days in March:
10.8 days - Average rainfall days in April:
14.7 days - Average rainfall days in May:
16.2 days - Average rainfall days in June:
17.3 days
- Average rainfall days in July:
14.1 days - Average rainfall days in August:
13 days - Average rainfall days in September:
11.2 days - Average rainfall days in October:
9.5 days - Average rainfall days in November:
6.9 days - Average rainfall days in December:
4.8 days
The month with the highest number of rainy days is June (17.3 days).
The month with the least rainy days is February (3.4 days).
Average snowfall
Herndon, IA
- Average snowfall in January:
4.29" - Average snowfall in February:
3.66" - Average snowfall in March:
1.89" - Average snowfall in April:
1.26" - Average snowfall in May:
0.12" - Average snowfall in June:
0"
The month with the highest snowfall is January (4.29").
The months with the least snowfall are June, July, August and September (0").
Average snowfall days
Herndon, IA
- Average snowfall days in January:
9.8 days - Average snowfall days in February:
8.8 days - Average snowfall days in March:
5.2 days - Average snowfall days in April:
1.7 days - Average snowfall days in May:
0.3 days - Average snowfall days in June:
0 days
- Average snowfall days in July:
0 days - Average snowfall days in August:
0 days - Average snowfall days in September:
0 days - Average snowfall days in October:
0.6 days - Average snowfall days in November:
3.4 days - Average snowfall days in December:
8.3 days
The month with the highest number of snowfall days is January (9.8 days).
The months with the least snowfall days are June, July, August and September (0 days).
Average daylight / Average sunshine
Herndon, IA
- Average daylight in January:
9h and 4min - Average daylight in February:
10h and 4min - Average daylight in March:
12h and 0min - Average daylight in April:
13h and 2min - Average daylight in May:
14h and 4min - Average daylight in June:
15h and 1min
- Average daylight in July:
14h and 5min - Average daylight in August:
13h and 5min - Average daylight in September:
12h and 3min - Average daylight in October:
11h and 1min - Average daylight in November:
9h and 5min - Average daylight in December:
9h and 1min
The month with the longest days is June (Average daylight: 15h and 12min).
The month with the shortest days is December (Average daylight: 9h and 12min).
- Average sunshine in January:
4h and 1min - Average sunshine in February:
4h and 5min - Average sunshine in March:
5h and 5min - Average sunshine in April:
7h and 5min - Average sunshine in May:
8h and 4min - Average sunshine in June:
9h and 3min
- Average sunshine in July:
10h and 1min - Average sunshine in August:
9h and 4min - Average sunshine in September:
9h and 2min - Average sunshine in October:
5h and 4min - Average sunshine in November:
5h and 4min - Average sunshine in December:
4h and 4min
The month with the most sunshine is July (Average sunshine: 10h and 12min).
The month with the least sunshine is January (Average sunshine: 4h and 12min).
Average sunshine days
Herndon, IA
- Average sunshine days in January:
18.1 days - Average sunshine days in February:
16.5 days - Average sunshine days in March:
16 days - Average sunshine days in April:
12.9 days - Average sunshine days in May:
13.3 days - Average sunshine days in June:
11.1 days
- Average sunshine days in July:
14.3 days - Average sunshine days in August:
16.3 days - Average sunshine days in September:
17.2 days - Average sunshine days in October:
19.2 days - Average sunshine days in November:
19.4 days - Average sunshine days in December:
18.8 days
The month with the most sunshine days is November (19.4 days).
The month with the least sunshine days is June (11.1 days).
Average UV index
Herndon, IA
The months with the highest UV index are June and July (UV index 6).
The months with the lowest UV index are January, February, October, November and December (UV index 2).
Average cloud cover
Herndon, IA
The month with the most cloud cover is January (Cloud cover 55).
The months with the least cloud cover are July and September (Cloud cover 30).
Average visibility
Herndon, IA
The months with the highest visibility are February, March, April, May, June, September, October, November and December (6mi).
The months with the lowest visibility are January, July and August (5mi).
Herndon, Iowa, USA
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