Climate and monthly weather forecast
Sioux City, IA

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Panorama of the vast Sioux City, Iowa
Panorama of the vast Sioux City, Iowa

The climate of Sioux City

Sioux City, situated in Iowa, USA, is categorized under the Köppen climate classification as 'Dfa', indicating a Humid continental climate characterized by no dry season and hot summer. The geographical location of the city considerably influences its climate, providing a blend of diverse weather conditions throughout the year.

A sweeping glance at the climatic data for Sioux City reveals significant variations in weather conditions from season to season, with diverse temperature ranges, rainfall patterns, and levels of humidity. December and January record the lowest average high temperatures of 27°F (-2.8°C) and 31.1°F (-0.5°C) respectively, transitioning gradually to warmer months where July marks the hottest month of the year with an average high temperature of 83.8°F (28.8°C). Simultaneously, the lowest recorded temperatures occur in the winter months, plummeting to 13.5°F (-10.3°C) in January and gradually rising to 64.9°F (18.3°C) in July.

Relative humidity ranges from 80% to 83% in the winter months, slightly decreasing to 67% in April, and then oscillating between 75% to 70% during the period from June to September. Precipitation presents an intriguing pattern, with January and February receiving the least rainfall of 0.39" (10mm), gradually increasing to peak in June with 1.85" (47mm), followed by a steady decline.

Remarkably, Sioux City experiences its maximum snowfall in January with 1.77" (45mm) and December with 1.42" (36mm). The city revels under its longest daylight hours in June, boasting 15.3 hours. Furthermore, the UV index stretches its maximum reach to 6 during June and July, necessitating shields of protection for outdoor activities.

The best time to visit Sioux City

Navigating through the layers of climatic data, it becomes evident that the best time to visit Sioux City lies between May and October. The city basks under average high temperatures ranging from 70°F (21.1°C) to 83.8°F (28.8°C) during these months. From May to September, the daylight hours are more generous, with an average duration varying between 14.6 hours to 15.3 hours, providing ample time for tourists to explore the city’s attractions.

The worst time to visit Sioux City

Making prudent travel plans involves circumventing the less hospitable climate phases. In the context of Sioux City, that period would span December to February. The city shivers under biting cold during these months, with average low temperatures lingering between 13.5°F (-10.3°C) to 17.1°F (-8.3°C)., and the landscape getting a cover of snow with daily temperatures often veering towards single-digit frigidness.

Spring weather in Sioux City

As Sioux City steps into spring, the city thaws from its winter chill. The months between March to May witness a warming trend as average high temperatures flutter between 46.8°F (8.2°C) to 70°F (21.1°C). The snowfall recedes significantly, with only 0.59" (15mm) recorded in March and no snowfall observed in April and May. The daylight period extends from 12 hours in March to 14.6 hours by May, inviting citizens and tourists to step outdoors and soak in the vibrant change of season.

Summer weather in Sioux City

Summer in Sioux City, unfolding between June and August, is characterized by warm temperatures, enhanced daylight and modest rainfall. The average high temperatures oscillate between 80.1°F (26.7°C) in June to a peak of 83.8°F (28.8°C) in July, tapering slightly to 81.9°F (27.7°C) in August. Despite the heat, Sioux City receives a decent share of rainfall throughout the summer season, with June recording the maximum rainfall of 1.85" (47mm).

Autumn weather in Sioux City

As autumn breezes into Sioux City from September to November, there is a cooling undercurrent. The temperatures gracefully drop from the summer highs, commencing at 75.6°F (24.2°C) in September and leveling down to 46.8°F (8.2°C) by November. The rainfall pattern also follows a downturn, starting with 1.26" (32mm) in September and dwindling to mere 0.47" (12mm) by November.

Winter weather in Sioux City

Winter in Sioux City, extending from December to February, is adorned with a blanket of snow, short daylight periods, and often freezing temperatures. These months experience the lowest temperatures, with January recording the lowest peak temperature of 27°F (-2.8°C). Snowfall is an integral part of Sioux City's winter tapestry, with January witnessing the most significant snowfall of 1.77" (45mm). The daylight hours shrink dramatically to approximately 9.5 hours in December to 10.6 hours by February. Despite the chill, the city shines in its winter glory, presenting an entirely different, serene panorama.

Weather in January

After the relative calm of December, January ushers in the new year with a noticeable drop in temperature reaching a high of 27°F (-2.8°C) and a low of 13.5°F (-10.3°C). High relative humidity, reaching 83%, indicates that the cold bites more than the thermometer might suggest. Weather in January »

Weather in February

As winter progresses into February in Sioux City, the slightly higher temperatures signal the beginning of the end for the harsh winter conditions. Although the cold persists, significant climatic variations become apparent as the city begins to transition into spring. Weather in February »

Weather in March

March, a transitional period, often sees some of the most variable weather in Sioux City. While higher temperature averages signify the welcome arrival of spring, occasional cold snaps remain a possibility. In terms of precipitation, both rainy and snowy days become less frequent, further reiterating the general shift in climate. Weather in March »

Weather in April

April brings warmer temperatures and longer days to Sioux City, with an average high of 58.6°F (14.8°C) and 13.4 hours of daily daylight. April also carries the highest average wind speed of the year, 11mph (17.7km/h), increasing the chance of local windstorms. Weather in April »

Weather in May

May stands as the doorway to summer in Sioux City. The appreciable warming and the increase in daily sunlight are surefire signs that the city is changing seasons. Being the second rainiest month of the year, as compared to April, seeing 1.85" (47mm) of rainfall means storms are likely. Weather in May »

Weather in June

June presents Sioux City with the official start of summer, evident in the longer days and the increase in average high temperatures. Riverside dips become a regular activity, as the UV index hits a year-long high of 6. Despite seeing the highest level of rainfall for the year at 1.85" (47mm), this month mostly brings with it the promise of brighter and sunnier days. Weather in June »

Weather in July

July's distinctive weather pattern sets it up as Sioux City's warmest month, with high temperatures averaging at 83.8°F (28.8°C) and low temperatures at 64.9°F (18.3°C). July is when summer hits its peak in Sioux City, supported by the increase in daily sunshine and longer days. Weather in July »

Weather in August

August's weather varies only slightly from July's, with slightly lower temperatures. Sioux City continues its summer theme with mostly hot, long days making it a great time for water-based activities and events. Though residents anticipate these lower temperatures, August's climatic conditions remain well within a summer frame. Weather in August »

Weather in September

September welcomes autumn in Sioux City, with a considerable drop in temperature. The average high temperature drops to 75.6°F (24.2°C), and there is a notable decrease in daylight hours. Although it marks the beginning of autumn, September experiences a balance of warm-crisp days and cool nights. Weather in September »

Weather in October

October marks a significant shift in Sioux City's weather as the festival of fall colors is in full swing. Sioux City's landscapes don hues of gold, red, and orange that are indicative of the cooler October days. The air turns crisper, and there's a noticeable nip in the evenings and mornings. Weather in October »

Weather in November

With the change in season, November's weather introduces Sioux City residents to the early stages of winter. A steady decrease in temperature, daylight hours, and an increase in relative humidity are signs of the forthcoming winter season. Weather in November »

Weather in December

Sioux City witnesses a full transition into the winter season in December. The cold intensifies, and there’s an increase in relative humidity at 81%. Despite the winter, Sioux City maintains a festive atmosphere with holiday decorations adorning the city. Weather in December »
Updated: Jun 22, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

What is the coldest month?

The month of January, characterized by an average high of 27°F (-2.8°C) and a low of 13.5°F (-10.3°C), is recognized as the coldest.

What is the most humid month?

The most humid month is January, with an average relative humidity of 83%.

What is the driest month?

The months with the least rainfall are January and February Rain falls for 2.6 days and accumulates 0.39" (10mm) of rain.

How much does it rain?

Throughout the year, there are 102.3 rainfall days, and 12.91" (328mm) of precipitation is accumulated.

When does it snow?

January through April, October through December are months with snowfall.

What is the snowiest month?

The month with the most snowfall is January, when snow falls for 8.2 days and typically aggregates up to 1.77" (45mm) of snow.

How much does it snow?

In Sioux City, during the entire year, snow falls for 31.1 days and aggregates up to 6.85" (174mm) of snow.

What is the month with the least sunshine?

With an average of 4.5h of sunshine, January has the least sunshine of the year.

What is the month with the lowest UV index in Sioux City?

January is the month with the lowest UV index, with an average maximum UV index of 1.

When is Daylight Saving Time (DST)?

On Sunday, March 10. 2024, at 2:00 am, Daylight Saving Time starts in Sioux City, 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.

When it does not snow in Sioux City?

In Sioux City, snow does not fall in May through September.

What is the rainiest month?

The month with the most rainfall is June, when the rain falls for 14.6 days and typically aggregates up to 1.85" (47mm) of precipitation.

When are the longest days?

June has the longest days of the year, with an average of 15h and 12min of daylight.

When is the highest UV index?

The months with the highest UV index are June and July, with an average maximum UV index of 6.

What month is the hottest?

July, recording an average high temperature of 83.8°F (28.8°C) and a low temperature of 64.9°F (18.3°C), is Sioux City's warmest month.

What month has the most sunshine?

With an average of 10.7h 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 65%.

What is the month with the shortest days?

The month with the shortest days is December, with an average of 9h and 6min of daylight.

Average temperature
Sioux City, IA

Average temperature - Sioux City, IA

The warmest month (with the highest average high temperature) is July (83.8°F).
The month with the lowest average high temperature is January (27°F).

The month with the highest average low temperature is July (64.9°F).
The coldest month (with the lowest average low temperature) is January (13.5°F).

Average pressure
Sioux City, IA

Average pressure - Sioux City, IA

The month with the highest atmospheric pressure is January (30.16"Hg).
The month with the lowest atmospheric pressure is June (29.86"Hg).

Average wind speed
Sioux City, IA

Average wind speed - Sioux City, IA

The windiest month (with the highest average wind speed) is April (11mph).
The calmest month (with the lowest average wind speed) is July (7.5mph).

Average humidity
Sioux City, IA

Average humidity - Sioux City, IA

The month with the highest relative humidity is January (83%).
The month with the lowest relative humidity is October (65%).

Average rainfall
Sioux City, IA

Average rainfall - Sioux City, IA

The wettest month (with the highest rainfall) is June (1.85").
The driest months (with the least rainfall) are January and February (0.39").

Average rainfall days
Sioux City, IA

Average rainfall days - Sioux City, IA

The month with the highest number of rainy days is June (14.6 days).
The month with the least rainy days is January (2.6 days).

Average snowfall
Sioux City, IA

Average snowfall - Sioux City, IA

The month with the highest snowfall is January (1.77").
The months with the least snowfall are May, June, July, August and September (0").

Average snowfall days
Sioux City, IA

Average snowfall days - Sioux City, IA

The month with the highest number of snowfall days is January (8.2 days).
The months with the least snowfall days are May, June, July, August and September (0 days).

Average daylight / Average sunshine
Sioux City, IA

Average daylight / Average sunshine - Sioux City, IA

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 6min).

The month with the most sunshine is July (Average sunshine: 10h and 42min).
The month with the least sunshine is January (Average sunshine: 4h and 30min).

Average sunshine days
Sioux City, IA

Average sunshine days - Sioux City, IA

The month with the most sunshine days is January (22.6 days).
The month with the least sunshine days is June (13.1 days).

Average visibility
Sioux City, IA

Average visibility - Sioux City, IA

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).

Sioux City, Iowa, USA

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