Contents
- Weather in January
- Frequently asked questions
- Average temperature in January
- Average pressure in January
- Average wind speed in January
- Average humidity in January
- Average rainfall in January
- Average rainfall days in January
- Average snowfall in January
- Average snowfall days in January
- Average daylight in January
- Average sunshine in January
- Average sunshine days in January
- Average UV index in January
- Average cloud cover in January
- Average visibility in January
Weather in January
Temperature
January, with an average high of 27.9°F (-2.3°C) and a low of 14.4°F (-9.8°C), signifies the coldest month of the year.Humidity
January is the most humid month in Johnston, with an average relative humidity of 83%.Rainfall
January is the month with the least rainfall. Rain falls for 3.8 days and accumulates 0.47" (12mm) of precipitation.Snowfall
Months with snowfall are January through May, October through December. The month with the most snowfall is January, when snow falls for 8.4 days and typically aggregates up to 2.2" (56mm) of snow.Daylight
In Johnston, the average length of the day in January is 9h and 34min.On the first day of the month, sunrise is at 7:41 am and sunset at 4:54 pm. On the last day of January, sunrise is at 7:27 am and sunset at 5:28 pm CST.
Sunshine
The month with the least sunshine is January, with an average of 4.3h of sunshine.UV index
January is the month with the lowest UV index, with an average maximum UV index of 1. A UV Index reading of 2, and below, represents a low threat to health from unsafe exposure to UV radiation for average individuals.Note: The maximum daily UV index, 1 in January, converts into the following recommendations:
It is important to always shield children, babies, and individuals with sensitive skin from prolonged exposure to the sun. The solar radiation around mid-day is intense; avoid the Sun and stay safe. A wide-brimmed hat provides unparalleled sun protection for sensitive areas like the eyes, ears, and neck. Be vigilant! The reflective nature of snow can increase the Sun's UV radiation nearly twofold.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What is the coldest time of year?
How cold is January?
What is the most humid month?
What is the average humidity in January?
What is the driest month?
How many days does it rain in January in Johnston?
What is the snowiest month?
How much does it snow in January?
What is the average length of the day in January?
What time are sunrise and sunset in January?
What is the month with the least sunshine in Johnston?
How many hours of sunshine does Johnston have in January?
When is the lowest UV index?
What is the UV index intensity in January?
Average temperature in January
Johnston, IA
- Average high temperature in January: 27.9°F
The warmest month (with the highest average high temperature) is July (82.4°F).
The month with the lowest average high temperature is January (27.9°F).
- Average low temperature in January: 14.4°F
The month with the highest average low temperature is July (65.1°F).
The coldest month (with the lowest average low temperature) is January (14.4°F).
Average pressure in January
Johnston, IA
- Average pressure in January: 30.16"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 in January
Johnston, IA
- Average wind speed in January: 10.3mph
The windiest month (with the highest average wind speed) is April (10.4mph).
The calmest months (with the lowest average wind speed) are July and August (7mph).
Average humidity in January
Johnston, IA
- Average humidity in January: 83%
The month with the highest relative humidity is January (83%).
The month with the lowest relative humidity is October (70%).
Average rainfall in January
Johnston, IA
- Average rainfall in January: 0.47"
The wettest months (with the highest rainfall) are May and June (2.52").
The driest month (with the least rainfall) is January (0.47").
Average rainfall days in January
Johnston, IA
- Average rainfall days in January: 3.8 days
The month with the highest number of rainy days is May (16.3 days).
The month with the least rainy days is February (3.5 days).
Average snowfall in January
Johnston, IA
- Average snowfall in January: 2.2"
The month with the highest snowfall is January (2.2").
The months with the least snowfall are June, July, August and September (0").
Average snowfall days in January
Johnston, IA
- Average snowfall days in January: 8.4 days
The month with the highest number of snowfall days is January (8.4 days).
The months with the least snowfall days are June, July, August and September (0 days).
Average daylight in January /
Average sunshine in January
Johnston, IA
- Average daylight in January: 9h and 4min
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 2min
The month with the most sunshine is July (Average sunshine: 10h and 24min).
The month with the least sunshine is January (Average sunshine: 4h and 18min).
Average sunshine days in January
Johnston, IA
- Average sunshine days in January: 20.6 days
The month with the most sunshine days is December (22.8 days).
The month with the least sunshine days is June (11.2 days).
Average UV index in January
Johnston, IA
- Average UV index in January: 1
The months with the highest UV index are June and July (UV index 6).
The month with the lowest UV index is January (UV index 1).
Average cloud cover in January
Johnston, IA
- Average cloud cover in January: 53
The month with the most cloud cover is January (Cloud cover 53).
The month with the least cloud cover is September (Cloud cover 28).
Average visibility in January
Johnston, IA
- Average visibility in January: 6mi
The months with the highest visibility are January, February, March, April, May, June, August, September, October, November and December (6mi).
The month with the lowest visibility is July (5mi).
Johnston, Iowa, USA
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