Climate and monthly weather forecast
Irmo, SC

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The climate of Irmo

Irmo, South Carolina, USA, is characterized by a Humid subtropical climate, noted as Cfa in the Köppen climate classification. This suggests that the town endures no dry season and has consistently humid conditions.

The annual temperature in Irmo transitions from a moderate low of 36.9°F (2.7°C) in January to a warm high of 91.4°F (33°C) in July. It is evident that the temperature fluctuates throughout the months, providing a diverse range of weather conditions for the year. Humidity levels can also encompass a small range from 70% in the warmest months to 75% in the colder months, offering damp conditions most times.

Precipitation patterns reveal that rainfall remains reasonably steady across the year, with a slight increase from 2.01" (51mm) in January to 3.11" (79mm) in December. On the other hand, the number of days with rain tends to peak in July, reaching up to a maximum of 17.4 days. Notably, snowfall is nearly absent in Irmo, peaking just at 0.24" (6mm) in January and 0.08" (2mm) in December and zero out for the rest of the year.

The best time to visit Irmo

The optimal time to visit Irmo would be the period from May to July. During these months, the town experiences its highest sunshine hours, averaging around 10.8 hours a day in June and July. The average daily temperature ranges from a pleasant 81°F (27.2°C) to a warm high of 91.4°F (33°C), inviting for most outdoor activities. The humidity levels are at a moderately comfortable range, around 70% to 74%, making it bearable for most visitors. Despite the possibility of rainfall, the number of days with clear skies or low cloud percentages makes these months ideal for tourist activities.

The worst time to visit Irmo

The least welcoming time to visit Irmo might be the chilly months from November to February. During this span, temperatures can fall to 36.9°F (2.7°C) in January, the lowest of the year. While snowfall is infrequent, the couple of inches present in winter could result in damp conditions, further reducing comfort levels. The lower daylight hour, averaging from 9.9 hours to 10.4 hours in these months, can lead to shorter days and less time for outdoor explorations.

Spring weather in Irmo

In Irmo, the months of March, April, and May, constitute the spring season. The highest temperature averages 73.4°F (23°C) in May, with the lowest temperature averaging from 46°F (7.8°C) in March up to 62.6°F (17°C) in May. The town also experiences acceleration of daylight hours, rising from 12 hours in March to 13.9 hours in May. Rainfall averages from 2.36" (60mm) in March to 2.68" (68mm) in May, suggesting frequent rainy days. Nevertheless, a rise in sunshine hours per day is noticeable, presenting a pleasant time to experience the city's charm.

Summer weather in Irmo

Encompassing months of June, July, and August, summer in Irmo is a showcase of warm and somewhat humid times. With a temperature gradient moving from 88.3°F (31.3°C) in June to 90°F (32.2°C) in August, the weather remains tropical. Precipitation figures slightly elevate, with July receiving the highest rainfall of 2.48" (63mm). Days with sunshine dominate the weather outlook, and a relative reduction is seen in cloud percentage. Taking into account these conditions, Irmo's summer is warm, lively, and perfect for sun-soaked ventures.

Autumn weather in Irmo

As the town moves into the autumn months of September to November, the climate undergoes a palpable shift. A steady decline in temperatures is noticed, starting at 84.7°F (29.3°C) in September and reaching down to 62.2°F (16.8°C) by November. Correspondingly, there is a decrease in daylight hours, which fall from 12.4 hours to 10.4 hours. The rainfall increases slightly in September and reduces again in November. Despite this, autumn's cooler temperatures and reducing humidity make it a scenic time to visit.

Winter weather in Irmo

The winter season in Irmo comprises the months from December through to February. The temperatures during these months fall to an average low of 36.9°F (2.7°C) in January and average high around 55.8°F (13.2°C) in December. The duration of daylight is also least during these months, averaging about 10 hours a day. Snowfall is minimal yet adds a different dimension to the township's climate. With increased cloud coverage and cooler temperatures, Irmo's winters are a stark contrast to its humid subtropical climate experienced throughout the year.

Weather in January

The advent of the new year brings cooler weather, with January being one of the coldest months in Irmo, South Carolina. Visitors and residents alike will feel the need for layers, as chilly temperatures prevail over the region. Weather in January »

Weather in February

February continues the trend of cooler temperatures in Irmo but also serves as an introduction to warmer days ahead. The weather remains stable, with minor fluctuations in temperature marking the transition from winter to spring. Weather in February »

Weather in March

March signals the start of spring in Irmo, leading to the gradual rise in prevailing weather conditions. Clear skies and longer daylight hours signify the seasonal change. Warmer temperatures start to emerge, yet the rainfall increases to 2.36" (60mm), making this month relatively wet. Weather in March »

Weather in April

In April, the true essence of spring is reflected in the weather with temperatures rising on a consistent basis. This time of the year is characterized by abundant sunshine and clear skies, making it perfect for outdoor adventures. Weather in April »

Weather in May

May is the transition period between spring and summer in Irmo, marked by pleasing weather which is ideal for all sorts of outdoor activities. With consistent increase in temperatures, basking in the sun becomes a daily routine. A marginal rise in rainfall, at 2.68" (68mm), signifies a moist atmosphere, yet it is not strong enough to dampen the spirits. Weather in May »

Weather in June

June is the marker of summer's arrival in Irmo with temperatures soaring and causing a noticeable change in the climate. It is during this month that people start hitting the beach, having picnics, and generally spending more time outdoors. Weather in June »

Weather in July

Welcome to the warmest and sunniest part of the year as July welcomes peak summer. Tourists and locals don their summer clothing and venture out to savor the delightful seasonal conditions. The peak temperature of the entire year, around 91.4°F (33°C), can be observed during July, making it the hottest month. Weather in July »

Weather in August

August maintains the trend of high temperatures though there is a slight relief from the heat compared to July. The weather is still largely warm, characterized by long, sunny days inviting for dips in the pool or lounging by the beach. Weather in August »

Weather in September

September brings with it the onset of autumn, and a welcome respite from the summer heat in Irmo. The weather gradually cools down, inviting the beauty of fall and making outdoor activities even more enjoyable. The drop in temperature is complemented by a decrease in rainfall, registering only 1.54" (39mm), the lowest of the year. Weather in September »

Weather in October

October is the month where autumn firmly establishes itself, bringing abundant fall foliage and comfortable temperatures perfect for enjoying the outdoors. This is the month when pumpkin patches and cozy sweaters become the norm, greatly enhancing the Irmo experience. Weather in October »

Weather in November

November in Irmo showcases a significant drop in temperatures, announcing the advent of the winter season. The weather, although colder, still allows for pleasant outdoor activities as the fall season comes to a close. Rainfall witnesses a slight decline, marking 1.93" (49mm), making November relatively less wet. Weather in November »

Weather in December

In December, Irmo, South Carolina, experiences the chill of winter with temperatures hitting their lowest for the year. It's a time of year marked by cozy indoor activities, warm drinks, and the holiday season. A slight snowfall of 0.08" (2mm) can be witnessed, indicating the arrival of winter. Weather in December »
Updated: Aug 16, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

What are the coldest months?

January, characterized by an average high temperature of 52.3°F (11.3°C) and a low temperature of 36.9°F (2.7°C), is generally the coldest month.

How many days does it rain?

Throughout the year, in Irmo, South Carolina, there are 147.8 rainfall days, and 28.23" (717mm) of precipitation is accumulated.

When does it snow?

January through March and December are months with snowfall in Irmo.

How much does it snow?

Throughout the year, in Irmo, there are 1.2 snowfall days, and 0.79" (20mm) of snow is accumulated.

When is the lowest UV index?

January is the month with the lowest UV index, with an average maximum UV index of 2.

When does it snow the most?

February is the month with the most snowfall. Snow falls for 0.4 days and accumulates 0.43" (11mm) of snow.

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 EST to EDT. Daylight Saving Time ends Sunday, November 3. 2024, at 2:00 am, and the time zone reverts from EDT to EST.

When it does not snow?

In Irmo, snow does not fall in April through November.

When are the longest days?

With an average of 14h and 24min of daylight, June has the longest days of the year.

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 7.

What time of the year is the hottest?

Irmo experiences its average highest temperatures in July, reaching a peak of 91.4°F (33°C) and a minimum of 72.9°F (22.7°C).

What is the least humid month?

July is the least humid month, with an average relative humidity of 70%.

What month has the most sunshine?

The month with the most sunshine is July, with an average of 10.9h of sunshine.

What is the driest month?

The month with the least rainfall is September, when the rain falls for 12 days and typically collects 1.54" (39mm) of precipitation.

What is the most humid month?

With an average relative humidity of 75%, December is the most humid month.

What is the rainiest month?

The month with the most rainfall is December, when the rain falls for 11.1 days and typically aggregates up to 3.11" (79mm) of precipitation.

What is the month with the shortest days?

With an average of 9h and 54min of daylight, December has the shortest days of the year.

What is the month with the least sunshine?

With an average of 5.5h of sunshine, December has the least sunshine of the year.

Average temperature
Irmo, SC

Average temperature - Irmo, SC

The warmest month (with the highest average high temperature) is July (91.4°F).
The month with the lowest average high temperature is January (52.3°F).

The month with the highest average low temperature is July (72.9°F).
The coldest month (with the lowest average low temperature) is January (36.9°F).

Average pressure
Irmo, SC

Average pressure - Irmo, SC

The months with the highest atmospheric pressure are January, November and December (30.14"Hg).
The month with the lowest atmospheric pressure is June (29.97"Hg).

Average wind speed
Irmo, SC

Average wind speed - Irmo, SC

The windiest month (with the highest average wind speed) is April (8.3mph).
The calmest month (with the lowest average wind speed) is August (5.3mph).

Average rainfall
Irmo, SC

Average rainfall - Irmo, SC

The wettest month (with the highest rainfall) is December (3.11").
The driest month (with the least rainfall) is September (1.54").

Average rainfall days
Irmo, SC

Average rainfall days - Irmo, SC

The month with the highest number of rainy days is July (17.4 days).
The month with the least rainy days is October (7.8 days).

Average snowfall
Irmo, SC

Average snowfall - Irmo, SC

The month with the highest snowfall is February (0.43").
The months with the least snowfall are April, May, June, July, August, September, October and November (0").

Average snowfall days
Irmo, SC

Average snowfall days - Irmo, SC

The month with the highest number of snowfall days is January (0.5 days).
The months with the least snowfall days are April, May, June, July, August, September, October and November (0 days).

Average daylight / Average sunshine
Irmo, SC

Average daylight / Average sunshine - Irmo, SC

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).

The month with the most sunshine is July (Average sunshine: 10h and 54min).
The month with the least sunshine is December (Average sunshine: 5h and 30min).

Average sunshine days
Irmo, SC

Average sunshine days - Irmo, SC

The month with the most sunshine days is October (21.8 days).
The month with the least sunshine days is July (10.8 days).

Average cloud cover
Irmo, SC

Average cloud cover - Irmo, SC

The months with the most cloud cover are February and December (Cloud cover 41).
The months with the least cloud cover are June and October (Cloud cover 28).

Average visibility
Irmo, SC

Average visibility - Irmo, SC

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).

Irmo, South Carolina, USA

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