May Weather in St. Louis, United States

Last updated: February 24, 2025

In St. Louis, the weather in May presents a vibrant tapestry of conditions ideal for both outdoor enthusiasts and those seeking a cozy retreat. With a maximum temperature reaching 34°C (94°F) and an average of 20°C (68°F), sunny days beckon for fun and exploration. However, evening chill can surprise with a minimum of 4°C (40°F). This month also sees notable precipitation, totaling 145 mm (5.7 in) over approximately 14 days, giving the landscape a lush, green ambiance. Coupled with an humidity level of 82%, the air feels refreshing yet rich, setting the stage for a dynamic experience in the heart of the Midwest.

May Temperature in St. Louis

As spring transitions into summer, May brings a delightful warmth to St. Louis, with temperatures showcasing a significant rise. The month begins with a minimum of 4°C (40°F), steadily climbing to an average of 20°C (68°F) and peaking at a striking 34°C (94°F). This notable increase in warmth marks a stark contrast to the winter months, where frigid lows dip to -22°C (-7°F) in January. May serves as a bridge between the cooler temperatures of earlier months and the sultry heat of summer, creating an inviting atmosphere perfect for outdoor activities and festivities. Overall, the gradual warming trend reflects the city's vibrant shift toward the balmy days of summer.

May Weather in St. Louis: Daily Temperature Highs, Lows, and Averages

The chart illustrates May temperature patterns in St. Louis, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends.
JanFebMarAprMayJunJulAugSepOctNovDec323547556777807672594439
Data source: Temperature data for St. Louis generated using information from the Copernicus Climate Change Service.
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The average of daily temperatures (24 hours) calculated across all days in the month.

May Precipitation in St. Louis

In St. Louis, May marks the peak of precipitation, with 145 mm (5.7 in) of rain falling over an average of 14 days—the highest monthly totals so far in the year. This significant uptick from previous months signals a transition into the wetter season, as spring showers play a crucial role in nurturing the region's blossoming flora. Following the relatively damp April with 129 mm of rain, May’s increased precipitation not only enhances the vibrant landscape but also contributes to the formation of summer thunderstorms that can dominate June and July. As the city prepares for summer, the lush greenery serves as a refreshing reminder of nature's resilience, though it is important to stay prepared for the unpredictable weather patterns that often accompany these rainy days.

May Precipitation Trends in St. Louis

The chart displays monthly precipitation patterns in St. Louis, with values for each month alongside May's data, which is highlighted for easy comparison. It shows the amount of precipitation, providing insights into how May's conditions compare to those of other months.
JanFebMarAprMayJunJulAugSepOctNovDec768013112914510197130561057559
Data source: Precipitation data for May generated using information from the Copernicus Climate Change Service.
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May Humidity in St. Louis

As spring transitions into summer, May in St. Louis experiences humidity levels averaging 82%, mirroring January's moist conditions. This consistency highlights a trend where the city's humidity peaks during the late spring and early summer months, setting the stage for the sweltering heat that follows in June, which sees a slight rise to 83%. Interestingly, while the humidity remains largely stable throughout the early months of the year, there's a notable drop starting in September, paving the way for crisper autumn days. Overall, May serves as a bridge between the cooler, more humid winter months and the warmer, stickier summer ahead, allowing residents to enjoy the vibrancy of spring before the heat escalates.

May Average Humidity in St. Louis

This chart illustrates the average monthly humidity levels in St. Louis, with May's data highlighted for easy comparison. It shows the fluctuation in humidity throughout the year, allowing you to see how May's humidity levels compare to other months.
JanFebMarAprMayJunJulAugSepOctNovDec82%80%80%80%82%83%81%80%76%76%85%86%
Data source: Humidity data for May generated using information from the Copernicus Climate Change Service.

May UV Index in St. Louis

In May, St. Louis experiences a significant uptick in UV intensity, with the UV Index soaring to 10, placing it in the very high exposure category. This means that residents and visitors alike should be particularly cautious, as the burn time decreases to just 15 minutes under direct sun exposure. Following the increasing trend from earlier months, where January started at a moderate Index of 3 and climbed steadily, May's levels signal the height of spring's intensity. As summer approaches, it's crucial to stay informed about UV safety measures. For detailed insights and daily updates, you can check the St. Louis UV Index.

Maximum UV Index Levels in St. Louis for May

The chart shows the monthly maximum UV Index (UVI) for St. Louis in May, representing the highest UV radiation level. The UVI measures the intensity of ultraviolet radiation from the sun, indicating the potential risk of sunburn and UV-related health issues.
JanFebMarAprMayJunJulAugSepOctNovDec3569101110109643
Data source: St. Louis May UVI data generated using information from the Copernicus Climate Change Service.

UV Risk Categories

  •  Extreme (11+): Avoid the sun, stay in shade.
  •  Very High (8-10): Limit sun exposure.
  •  High (6-7): Use SPF 30+ and protective clothing.
  •  Moderate (3-5): Midday shade recommended.
  •  Low (0-2): No protection needed.

May Sunshine in St. Louis

As May unfolds in St. Louis, the city basks in a glorious 287 hours of sunshine, marking a significant increase from the earlier months. This trend of rising sunlight hours, peaking through spring into summer, highlights the remarkable transition from 125 hours in January to an impressive 328 hours in June. April's 241 hours set the stage for May's warmth, leading into the sun-drenched days of summer. Not only does May stand as a vibrant precursor to the bright summer months—where July reaches a peak of 348 hours—but it also serves as a vivid reminder of the city's natural beauty coming to life, inviting residents and visitors alike to enjoy the outdoors while soaking in the delightful rays.

Monthly Sunshine Duration in St. Louis: May Highlighted

The May sunshine duration represents the total number of hours St. Louis experiences direct sunlight during the month of May, excluding cloudy or obstructed periods. This chart compares the sunshine duration of May with the other months of the year.
JanFebMarAprMayJunJulAugSepOctNovDec125h174h205h241h287h328h348h330h290h239h211h197h
Data source: St. Louis May Sunshine duration data generated using information from the Copernicus Climate Change Service.

Chance of Sun in St. Louis During May

In St. Louis, the likelihood of sunny weather experiences a notable shift as the year progresses. January and February are characterized by a modest 30% chance of sunshine, gradually increasing to 44% in March and peaking at 49% in April. However, by May, the odds drop to just 26%, making it one of the less reliable months for sunshine. The trend of fluctuating sun chances continues into the summer, with July (51%) and August (47%) offering more favorable conditions. Interestingly, the sunshine returns later in the year, peaking in September at a robust 64%, before tapering off again. This pattern illustrates that while spring may seem promising, May's weather can be quite unpredictable in St. Louis.

Percentage of Sunny Days in May in St. Louis

The chart illustrates the percentage of sunny days in St. Louis throughout the year, with May highlighted. It highlights the variation in sunshine across each month and provides an overview of the typical frequency of sunny days, offering insights into how often St. Louis experiences clear skies throughout the year.
JanFebMarAprMayJunJulAugSepOctNovDec30%30%44%49%26%41%51%47%64%39%53%47%
Data source: St. Louis May chance of sun data, generated using information from the Copernicus Climate Change Service.

Daylight Hours in St. Louis in May

As spring unfolds into summer, St. Louis experiences a remarkable increase in daylight duration during May, boasting 14 hours of sunlight—a peak that aligns with the sunny trends of the months that follow. The journey begins in January with a modest 9 hours, gradually climbing to 11 hours in March and 13 hours by April, reflecting the awakening of nature. May not only continues this upward trajectory but also sets the stage for the consistent light provided through June and July. As summer transitions to fall, the daylight gradually dwindles, dropping back to 12 hours in September and subsequently declining to 10 hours in November. This rhythm of increasing and decreasing daylight mirrors the changing seasons, offering residents a vibrant blend of sunshine in the heart of spring and the warmth of summer.

Average Daylight Hours in St. Louis for May

The chart illustrates the variation in daylight duration in St. Louis throughout the year, with May highlighted. It shows the monthly changes in daylight hours, calculated by summing the hours between sunrise and sunset.
JanFebMarAprMayJunJulAugSepOctNovDec9h 47m10h 45m11h 58m13h 14m14h 17m14h 48m14h 31m13h 35m12h 23m11h 8m10h 2m9h 29m
Data source: St. Louis daylight hours, calculated by summing the hours between sunrise and sunset for each day.

May Winds in St. Louis

In May, St. Louis experiences a gentle breeze, with an average wind speed of 3.2 m/s (7 mph), making it slightly calmer than the preceding months of March and April. This decline may signal the transition into the warmer summer months, where winds typically lighten, as seen in June and July with average speeds dropping to 2.8 m/s (6 mph) and 2.1 m/s (5 mph) respectively. Interestingly, while May marks one of the quieter points in the spring season, the overall wind pattern showcases a clear trend: the city enjoys relatively moderate winds from the start of the year through late spring, before settling into the stillness of summer. This fluctuation not only influences the local climate but also sets the stage for the humid warmth that characterizes St. Louis summers, encouraging outdoor activities and leisurely strolls through the blossoming landscapes.

Average May Wind Speed in St. Louis

The chart displays monthly wind speed patterns in St. Louis, with values for each month shown alongside May's data, which is highlighted for easy comparison. It illustrates the average wind speed, offering insights into how May's wind conditions compare to the rest of the year.
JanFebMarAprMayJunJulAugSepOctNovDec3.33.73.83.53.2 m/s2.82.12.43.03.53.43.6
Data source: St. Louis May wind data, generated using information from the Copernicus Climate Change Service.

How May Weather in St. Louis Compares to Other Months

The weather in St. Louis changes throughout the year, offering a unique experience in each season. Below is a month-by-month comparison of May's weather with other months, highlighting differences in temperature, precipitation, and other key factors. Click on each section to discover seasonal trends in St. Louis and find detailed weather information for every month.

In May, temperatures are significantly warmer, ranging from a minimum of 4°C (40°F) to a maximum of 34°C (94°F), with an average of 20°C (68°F). This month experiences more precipitation, totaling 145 mm (5.7 in) across 14 days, while humidity remains high at 82%. In contrast, January features much colder temperatures, with a minimum of -22°C (-7°F) and a maximum of 19°C (67°F), averaging around 0°C (32°F). Precipitation is lower in January at 76 mm (3.0 in) over 8 days, but humidity is equally high at 82%. For more specific insights into January weather, you can refer to St. Louis weather in January.

May and February present stark contrasts in weather. In May, temperatures soar with a minimum of 4°C (40°F) and an average of 20°C (68°F), peaking at a high of 34°C (94°F). The month experiences significant precipitation, with 145 mm (5.7 in) over about 14 days and an average humidity of 82%. In contrast, February brings a chill, featuring a minimum temperature of -19°C (-1°F) and an average of only 2°C (35°F), while maxing out at 24°C (76°F). Despite receiving less precipitation at 80 mm (3.2 in) over about 10 days, February maintains a slightly lower humidity level of 80%. For more details on February weather, visit St. Louis weather in February.

When comparing the weather in May and March, we can see a stark contrast. May boasts milder temperatures with a minimum of 4°C (40°F) and an average of 20°C (68°F), reaching as high as 34°C (94°F). It experiences higher precipitation levels, totaling 145 mm (5.7 in) over 14 days, coupled with elevated humidity at 82%. In contrast, March is much colder, featuring a minimum temperature of -17°C (2°F) and an average of 8°C (47°F), with a maximum of 27°C (81°F). While March has slightly lower precipitation at 131 mm (5.2 in) over 12 days, the humidity is slightly less at 80%. For a closer look at March weather patterns, you can visit St. Louis weather in March.

In comparing the weather between April and May, May generally showcases a warmer climate with average temperatures climbing to 20°C (68°F), compared to April's average of 13°C (55°F). The maximum temperature in May can reach up to 34°C (94°F), whereas April's highest is 30°C (87°F). Precipitation levels are slightly higher in May, with 145 mm (5.7 in) over 14 days, compared to April's 129 mm (5.1 in) over 11 days. Humidity also increases in May, averaging 82%, compared to April's 80%. For more detailed information about April's weather, you can visit St. Louis weather in April.

May and June showcase a noticeable shift in weather patterns. In May, temperatures vary significantly, with a minimum of 4°C (40°F) and a maximum of 34°C (94°F), leading to an average of 20°C (68°F). This month also experiences higher precipitation with 145 mm (5.7 inches) spread across 14 days, contributing to a humid atmosphere with 82% humidity. In contrast, June sees warmer temperatures, with minimums at 12°C (54°F) and maximums climbing to 36°C (98°F), yielding an average of 25°C (77°F). Precipitation decreases to 101 mm (4.0 inches) over 11 days, while humidity remains slightly elevated at 83%. For more detailed weather insights, you can check St. Louis weather in June.

In a comparison of May and July weather, May experiences a wider temperature range, with minimums dipping to 4°C (40°F) and maximums soaring to 34°C (94°F), resulting in an average temperature of 20°C (68°F). In contrast, July boasts consistently warmer temperatures, with minimums starting at 16°C (61°F) and highs reaching up to 38°C (101°F), giving it a higher average of 26°C (80°F). Additionally, May sees more precipitation, totaling 145 mm (5.7 in) over 14 days, while July has less, with 97 mm (3.8 in) over 11 days. Humidity levels are similar, with May at 82% and July slightly lower at 81%. For a deeper dive into July weather specifics, you can check out St. Louis weather in July.

In comparing the weather in May and August, we see a notable shift in temperatures and precipitation patterns. May experiences a wider temperature range, with a minimum of 4°C (40°F) and a maximum of 34°C (94°F), averaging around 20°C (68°F). In contrast, August presents more consistently warm temperatures, with a minimum of 12°C (54°F) and a maximum of 35°C (96°F), averaging 25°C (76°F). Precipitation levels are slightly lower in August, receiving 130 mm (5.1 in) over 11 days compared to May's 145 mm (5.7 in) over 14 days. Humidity remains relatively high in both months, with May at 82% and August at 80%. For a more detailed look at August weather, check out St. Louis weather in August.

In May, temperatures range more widely, with minimums dipping to 4°C (40°F) and maximums soaring to 34°C (94°F), while the average hovers around a pleasant 20°C (68°F). This month experiences considerable rainfall, with 145 mm (5.7 in) spread over 14 days, contributing to a high humidity level of 82%. In contrast, September brings a more stable climate, featuring slightly warmer averages at 22°C (73°F) but with minimums at 7°C (45°F) and maximums peaking at 35°C (95°F). The month is notably drier, with just 56 mm (2.2 in) of precipitation over 7 days, resulting in a lower humidity of 76%. For a deeper dive into September's weather specifics, check out St. Louis weather in September.

When comparing the weather in May and October, we see notable differences in temperature and humidity. May boasts a warmer average temperature of 20°C (68°F) with highs reaching up to 34°C (94°F), while October's average drops to 15°C (59°F), though it also encounters maximum temperatures that can match May's at 34°C (93°F). Precipitation is more prevalent in May, with 145 mm (5.7 in) over 14 days compared to October’s 105 mm (4.1 in) over just 11 days. Humidity levels are also higher in May at 82%, compared to 76% in October, contributing to a distinctly different feel during these months. For specific details on October's weather, you can explore St. Louis weather in October.

May and November showcase significantly different weather patterns. May boasts a warm average temperature of 20°C (68°F), with maximum highs reaching up to 34°C (94°F), while November presents a much cooler average of 7°C (44°F), with maximums only reaching 25°C (78°F). May experiences higher precipitation levels at 145 mm (5.7 in) across about 14 days, compared to November's 75 mm (2.9 in) over 9 days. Additionally, humidity in both months is relatively high, with May at 82% and November slightly higher at 85%. For more details on November's climate, check out St. Louis weather in November.

May and December offer starkly contrasting weather conditions. In May, temperatures range from a mild 4°C (40°F) at their lowest to a pleasantly warm average of 20°C (68°F), peaking at an impressive 34°C (94°F). This month also brings significant rainfall, with 145 mm (5.7 in) of precipitation over about 14 days, coupled with relatively high humidity at 82%. In contrast, December experiences much colder temperatures, with lows plunging to -18°C (0°F) and an average temperature of just 4°C (39°F). While the maximum temperature can reach 22°C (71°F), December's precipitation is considerably less at 59 mm (2.3 in) over only 7 days, along with higher humidity at 86%. For a more detailed look, check out St. Louis weather in December.

Compare St. Louis's Climate with Cities Worldwide

Conclusion: What to Expect From May Weather in St. Louis

May in St. Louis brings a welcoming shift in weather, as the city transitions from the coolness of early spring to the warmth of summer. With an average temperature that feels pleasantly mild compared to the extremes of winter, this month often showcases a mix of sunny days and refreshing rainfall, contributing to the lushness of the landscape. However, the humidity can be quite high, laying the groundwork for the steamy summer ahead. This combination of warm days and occasional showers makes May a unique and vibrant time in St. Louis. To explore more about what to expect throughout the year, visit St. Louis Climate.