Contents
- Weather in May
- Frequently asked questions
- Average temperature in May
- Average pressure in May
- Average wind speed in May
- Average humidity in May
- Average rainfall in May
- Average rainfall days in May
- Average snowfall in May
- Average snowfall days in May
- Average daylight in May
- Average sunshine in May
- Average sunshine days in May
- Average UV index in May
- Average cloud cover in May
- Average visibility in May
Weather in May
Temperature
Johnston perceives a slight temperature ascent during May, with average high-temperatures adjusting from a warm 73.9°F (23.3°C) in April to a still moderately hot 81.1°F (27.3°C). In the month of May, the temperature generally rests at an average low of 62.2°F (16.8°C).Heat index
The heat index value for May is calculated to be a hot 86°F (30°C). Prolonged exposure combined with continuous activity could lead to exhaustion, and possibly heat cramps.When assessing, remember that heat index measurements are for light winds and shaded spots. An exposure to direct sunlight may lift the heat index values by 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'real feel' or 'apparent temperature', is a single figure representing how weather conditions feel when combining temperature and humidity. One's perception of temperature can vary depending on physical activity and individual heat sensitivity, influenced by factors like wind, attire, and metabolic variations. When directly under the sun, the weather's impact can intensify, possibly boosting the heat index by 15 Fahrenheit (8 Celsius) degrees. Heat index values hold particular importance for children. Young ones often ignore the need to take a break and drink fluids. Thirst is a late-stage symptom of dehydration - hence, maintaining hydration, particularly during extended physical activities, is crucial.
Humidity
In May, the average relative humidity is 74%.Rainfall
In Johnston, in May, it is raining for 14.8 days, with typically 2.8" (71mm) of accumulated precipitation. Throughout the year, there are 149.8 rainfall days, and 28.58" (726mm) of precipitation is accumulated.Snowfall
April through November are months without snowfall.Daylight
In May, the average length of the day is 13h and 56min.On the first day of May, sunrise is at 6:37 am and sunset at 8:11 pm. On the last day of the month, sunrise is at 6:17 am and sunset at 8:32 pm EDT.
Sunshine
In May, the average sunshine in Johnston is 10h.UV index
The average daily maximum UV index in May is 6. A UV Index value of 6 to 7 symbolizes a high threat to health from unprotected exposure to Sun's UV rays for average individuals.Note: The UV index of 6 in May translates into these instructions:
Take precautions and utilize sun safety practices. Protection against skin and eye damage is required. The Sun's UV radiation is most potent between the hours of 10 a.m. and 4 p.m. Try to avoid direct sunlight during this time. Boost your sun resistance with garments that are densely woven yet spacious.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What is the usual temperature for Johnston in May?
What is the average humidity in May?
How many days does it rain in May?
When it does not snow?
What is the average length of the day in May in Johnston?
What time are sunrise and sunset in May?
How long on average sun shines in May in Johnston?
How high is the UV index in May?
Average temperature in May
Johnston, SC
- Average high temperature in May: 81.1°F
The warmest month (with the highest average high temperature) is July (91.4°F).
The month with the lowest average high temperature is January (52.7°F).
- Average low temperature in May: 62.2°F
The month with the highest average low temperature is July (72.5°F).
The coldest month (with the lowest average low temperature) is January (36.9°F).
Average pressure in May
Johnston, SC
- Average pressure in May: 30.03"Hg
The months with the highest atmospheric pressure are January, November and December (30.14"Hg).
The month with the lowest atmospheric pressure is June (29.98"Hg).
Average wind speed in May
Johnston, SC
- Average wind speed in May: 6.7mph
The windiest months (with the highest average wind speed) are February and April (8.1mph).
The calmest month (with the lowest average wind speed) is August (5.2mph).
Average humidity in May
Johnston, SC
- Average humidity in May: 74%
The month with the highest relative humidity is December (76%).
The month with the lowest relative humidity is July (70%).
Average rainfall in May
Johnston, SC
- Average rainfall in May: 2.8"
The wettest month (with the highest rainfall) is December (3.03").
The driest month (with the least rainfall) is September (1.42").
Average rainfall days in May
Johnston, SC
- Average rainfall days in May: 14.8 days
The month with the highest number of rainy days is July (17.5 days).
The month with the least rainy days is November (7.8 days).
Average snowfall in May
Johnston, SC
- Average snowfall in May: 0"
The month with the highest snowfall is February (0.59").
The months with the least snowfall are April, May, June, July, August, September, October and November (0").
Average snowfall days in May
Johnston, SC
- Average snowfall days in May: 0 days
The months with the highest number of snowfall days are January and February (0.4 days).
The months with the least snowfall days are April, May, June, July, August, September and October (0 days).
Average daylight in May /
Average sunshine in May
Johnston, SC
- Average daylight in May: 13h and 5min
The month with the longest days is June (Average daylight: 14h and 24min).
The month with the shortest days is December (Average daylight: 9h and 54min).
- Average sunshine in May: 10h and 0min
The months with the most sunshine are June and July (Average sunshine: 10h and 54min).
The month with the least sunshine is December (Average sunshine: 5h and 24min).
Average sunshine days in May
Johnston, SC
- Average sunshine days in May: 14.7 days
The month with the most sunshine days is October (21.8 days).
The month with the least sunshine days is July (11.2 days).
Average UV index in May
Johnston, SC
- Average UV index in May: 6
The months with the highest UV index are June, July and August (UV index 7).
The month with the lowest UV index is January (UV index 2).
Average cloud cover in May
Johnston, SC
- Average cloud cover in May: 33
The month with the most cloud cover is December (Cloud cover 41).
The month with the least cloud cover is October (Cloud cover 27).
Average visibility in May
Johnston, SC
- Average visibility in May: 6mi
The months with the highest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
The months with the lowest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
Johnston, South Carolina, USA
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