May Weather in Boston, United States

Last updated: February 24, 2025

In May, Boston transforms into a vibrant hub of spring, offering a maximum temperature that can soar to 31°C (89°F), while the average hovers around a comfortable 14°C (58°F). Early mornings might still feel a bit brisk, with minimum temperatures dropping to 3°C (37°F). This month witnesses 94 mm (3.7 in) of precipitation spread across 12 days, contributing to the lushness of the city’s parks and gardens. With an average humidity level of 72%, the air is rich and fragrant, enhancing the city’s botanical beauty. As visitors experience Boston in May, the blend of warmth and occasional showers creates a refreshing atmosphere that highlights the essence of springtime in New England.

May Temperature in Boston

May in Boston marks a refreshing transition into warmer weather, with temperatures showing a significant upward trend compared to the chill of previous months. The month begins with a minimum of 3°C (37°F), rising to an average of 14°C (58°F) and peaking at a delightful 31°C (89°F). This marks a notable leap from April's temperatures, where the average was only 9°C (48°F). With the days growing longer and sunshine becoming more frequent, May invites residents and visitors alike to enjoy the blossoming scenery and outdoor activities. As the city shakes off the remnants of winter, May becomes a month of vibrant life, setting the stage for the warmth of summer ahead.

May Weather in Boston: Daily Temperature Highs, Lows, and Averages

The chart illustrates May temperature patterns in Boston, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends.
JanFebMarAprMayJunJulAugSepOctNovDec323438485767737366574436
Data source: Temperature data for Boston generated using information from the Copernicus Climate Change Service.
Choose your preferred temperature unit
The average of daily temperatures (24 hours) calculated across all days in the month.

May Precipitation in Boston

May in Boston sees a reasonable precipitation total of 94 mm (3.7 inches) spread across 12 days, making it one of the wetter months of the spring. Following the substantial rainfall in April with 135 mm (5.3 inches), May’s total represents a slight decline, hinting at the transition toward the drier summer months ahead. However, it’s still significant enough to maintain the lush greenery Boston is known for this time of year. Notably, the precipitation pattern in May closely mirrors that of June, which receives 86 mm (3.4 inches), suggesting a consistency in spring weather leading into early summer. This transition is part of a broader trend, as temperatures rise and outdoor activities begin to pick up, making the month a vibrant time for residents and visitors alike.

May Precipitation Trends in Boston

The chart displays monthly precipitation patterns in Boston, 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.
JanFebMarAprMayJunJulAugSepOctNovDec799710213594861157692149100125
Data source: Precipitation data for May generated using information from the Copernicus Climate Change Service.
Choose your preferred precipitation unit

May Humidity in Boston

As spring unfolds in Boston, May marks a noticeable drop in humidity, settling at 72%, mirroring the conditions of the following month, June. This decline represents a significant shift from the higher humidity levels seen in the earlier months, such as January and February, which hovered around 86% and 84% respectively. The transition from April, when humidity was 80%, to May brings a sense of relief as the air becomes crisper and more comfortable. Interestingly, the dry trend continues into the hotter summer months, with July and August experiencing even lower humidity, at 67% and 66%, respectively. This pattern highlights a gradual easing of moisture, paving the way for Boston's vibrant summer days filled with outdoor activities and sun-soaked adventures.

May Average Humidity in Boston

This chart illustrates the average monthly humidity levels in Boston, 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.
JanFebMarAprMayJunJulAugSepOctNovDec86%84%82%80%72%72%67%66%71%79%84%81%
Data source: Humidity data for May generated using information from the Copernicus Climate Change Service.

May UV Index in Boston

As May unfolds in Boston, the UV Index rises sharply to 9, categorizing exposure as very high and signaling a burn time of just 15 minutes. This notable increase from the previous months illustrates the transition from moderate to intense sun exposure, encouraging residents and visitors alike to adopt proactive sun protection measures. With the UV Index climbing steadily, peaking at 10 in June, it's crucial to stay vigilant as the warmer months approach. For those planning outdoor activities, understanding these trends helps underscore the importance of sun safety. To learn more about the UV Index throughout the year, visit Boston UV Index.

Maximum UV Index Levels in Boston for May

The chart shows the monthly maximum UV Index (UVI) for Boston 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.
JanFebMarAprMayJunJulAugSepOctNovDec3558910997642
Data source: Boston 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 Boston

As spring blossoms into summer, May shines brightly in Boston, unveiling an impressive 289 hours of sunshine — a delightful increase from the previous months. This spike exemplifies a trend of accumulating sunlight leading into the peak of summer, with May's sunshine marking a transition from the earlier cupped hands of winter. Following a steady rise from January’s 152 hours through March’s 253 hours, the city experiences an invigorating burst of energy as it emerges from spring’s embrace. This upward trajectory in daylight hours continues into June and July, where the city basks in 327 and 334 hours, respectively. May not only heralds warmer days but also sets the stage for Boston's sun-soaked summers, inviting residents and visitors alike to revel in the vibrant outdoor life.

Monthly Sunshine Duration in Boston: May Highlighted

The May sunshine duration represents the total number of hours Boston 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.
JanFebMarAprMayJunJulAugSepOctNovDec152h188h253h240h289h327h334h327h278h221h201h178h
Data source: Boston May Sunshine duration data generated using information from the Copernicus Climate Change Service.

Chance of Sun in Boston During May

As spring rolls into May, Boston's chances of enjoying sunny weather dip to 38%, slightly lower than the preceding months of March and April. Despite the promise of warmer days, this figure reflects a trend of variability as the city transitions between seasons. Notably, while the sun tends to peak in March, with a robust 61%, the likelihood of clear skies drops off and fluctuates through the summer months, landing at even lower probabilities in August, where sunshine chances dwindle to just 29%. This presents a picturesque, yet somewhat unpredictable weather pattern for those looking to bask in the spring sun.

Percentage of Sunny Days in May in Boston

The chart illustrates the percentage of sunny days in Boston 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 Boston experiences clear skies throughout the year.
JanFebMarAprMayJunJulAugSepOctNovDec44%32%61%42%38%40%33%29%44%40%55%33%
Data source: Boston May chance of sun data, generated using information from the Copernicus Climate Change Service.

Daylight Hours in Boston in May

As spring transitions into summer, Boston experiences a noticeable increase in daylight duration throughout May, with the sun illuminating the city for an impressive 14 hours each day. This surge follows the gradual progression seen from the 9 hours of daylight in January, steadily increasing to 11 hours in March and a vibrant 13 hours in April. The pattern reflects a clear upward trend as the year advances, peaking in June with 15 hours of daylight. Following May, July sees a slight dip to 14 hours, illustrating a gradual tapering as the days begin to shorten again. This seasonal rhythm not only enhances outdoor activities but also enriches the city's lively atmosphere, inviting residents and visitors alike to bask in the longer, sun-kissed days of spring.

Average Daylight Hours in Boston for May

The chart illustrates the variation in daylight duration in Boston throughout the year, with May highlighted. It shows the monthly changes in daylight hours, calculated by summing the hours between sunrise and sunset.
JanFebMarAprMayJunJulAugSepOctNovDec9h 28m10h 34m11h 57m13h 23m14h 36m15h 12m14h 53m13h 48m12h 25m11h9h 45m9h 7m
Data source: Boston daylight hours, calculated by summing the hours between sunrise and sunset for each day.

May Winds in Boston

In May, Boston experiences a gentle shift in its wind patterns as the average wind speed drops to 3.9 m/s (9 mph). This subtle decrease follows the gustier months of earlier spring, where March recorded a brisk 4.7 m/s (11 mph). As summer approaches, the winds tend to mellow, with June's speeds dipping even further to 3.7 m/s (8 mph). This trend reflects the calming transition into warmer months, creating a more relaxed atmosphere perfect for outdoor activities. Alongside the fluctuating wind speeds, May's mild breezes offer a pleasant reprieve from the harsher winds of winter, providing a refreshing backdrop for the vibrant life blooming throughout the city.

Average May Wind Speed in Boston

The chart displays monthly wind speed patterns in Boston, 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.
JanFebMarAprMayJunJulAugSepOctNovDec4.44.34.74.23.9 m/s3.73.23.13.74.14.14.1
Data source: Boston May wind data, generated using information from the Copernicus Climate Change Service.

How May Weather in Boston Compares to Other Months

The weather in Boston 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 Boston and find detailed weather information for every month.

When comparing the weather in May and January, one can observe stark contrasts. May typically welcomes milder temperatures, ranging from a minimum of 3°C (37°F) to an average of 14°C (58°F), with daytime highs soaring up to 31°C (89°F). The month also sees around 94 mm (3.7 in) of precipitation over approximately 12 days, coupled with a humidity level of 72%.

In contrast, January is characterized by much colder conditions, with temperatures dipping as low as -19°C (-3°F) and averaging around 0°C (32°F). The maximum temperature only reaches 19°C (67°F). Precipitation during this month is slightly lower at 79 mm (3.1 in) over 9 days, but the humidity is higher at 86%. For more detailed insights into Boston's January weather, you can refer to Boston weather in January.

In comparing the weather of May and February, one can observe significant differences in temperature and overall climate conditions. May boasts a much milder temperature range, with a minimum of 3°C (37°F) and a maximum reaching up to 31°C (89°F). In contrast, February typically experiences colder conditions, with temperatures ranging from a chilly -16°C (4°F) to a maximum of 20°C (68°F).

Precipitation levels are similar, with May receiving 94 mm (3.7 in) over 12 days and February slightly higher at 97 mm (3.8 in) over 10 days. However, February's higher humidity at 84% compared to May's 72% contributes to a damp, heavier feel in the air during the winter month. For more detailed insights into the climate during February, you can visit Boston weather in February.

Comparing the weather in May and March reveals significant differences in temperature and conditions. In May, temperatures range from a chilly 3°C (37°F) at night to a warm 31°C (89°F) during the day, with an average of 14°C (58°F). Although May sees a higher average temperature, it also experiences about 94 mm (3.7 in) of precipitation over 12 days, accompanied by a humidity level of 72%. In contrast, March is much cooler, with temperatures varying from a frigid -12°C (11°F) to a mild 20°C (68°F), and an average temperature of just 3°C (38°F). March tends to be wetter than May, with 102 mm (4.0 in) of precipitation over 10 days and higher humidity at 82%. For more in-depth information, visit Boston weather in March.

In comparing the weather of May and April, May generally experiences warmer temperatures, with a minimum of 3°C (37°F), an average of 14°C (58°F), and a maximum reaching 31°C (89°F). In contrast, April has cooler temperatures, with a minimum of -2°C (28°F) and an average of 9°C (48°F), peaking at 27°C (81°F). While May sees a decrease in precipitation to 94 mm (3.7 in) over 12 days, April is wetter, with 135 mm (5.3 in) over 13 days. Additionally, humidity remains slightly higher in April at 80%, compared to 72% in May. For more detailed insights, check out Boston weather in April.

May and June exhibit notable differences in weather patterns. In May, temperatures range from a chilly minimum of 3°C (37°F) to a warm maximum of 31°C (89°F), with an average of 14°C (58°F). The month experiences about 94 mm (3.7 inches) of precipitation over 12 days, leading to a humid atmosphere with a relative humidity of 72%.

In contrast, June brings slightly warmer temperatures, with a minimum of 8°C (47°F), an average of 19°C (67°F), and a maximum of 33°C (92°F). Precipitation decreases slightly to 86 mm (3.4 inches), occurring over 10 days, while the humidity remains consistent at 72%. For more detailed weather insights, you can explore Boston weather in June.

In comparing the weather of May and July, there are notable differences in temperature and precipitation. May experiences a wider range of temperatures, with minimums dropping to 3°C (37°F) and maximums reaching up to 31°C (89°F). The average temperature rests at a mild 14°C (58°F). In contrast, July sees a consistent warmth, with minimum temperatures starting at 14°C (57°F) and maximums climbing to 34°C (94°F), leading to a higher average of 23°C (73°F).

While both months receive similar amounts of precipitation, July totals slightly higher at 115 mm (4.5 in) compared to May's 94 mm (3.7 in), with both months seeing precipitation on approximately 12 days. Humidity levels are slightly lower in July at 67%, compared to May's 72%. For more details on July weather, check out Boston weather in July.

May and August present quite different weather experiences. In May, temperatures range from a chilly 3°C (37°F) at night to a warm 31°C (89°F) during the day, with an average of 14°C (58°F). This month sees considerable precipitation, totaling 94 mm (3.7 in) over 12 days, contributing to a humidity level of 72%. In contrast, August offers a warmer environment with minimum temperatures of 13°C (56°F) and maximums reaching 33°C (92°F), averaging around 23°C (73°F). Precipitation decreases to 76 mm (3.0 in) across 10 days, and humidity drops to 66%. For a detailed look at the summer climate, check out Boston weather in August.

May and September present a fascinating contrast in weather patterns. In May, temperatures range from a chilly 3°C (37°F) to a warm 31°C (89°F), with an average of 14°C (58°F). This month experiences about 94 mm (3.7 in) of precipitation over approximately 12 days, contributing to a relatively humid environment at 72%. Conversely, September boasts slightly milder temperatures, with a minimum of 7°C (46°F), an average of 19°C (67°F), and a maximum of 33°C (92°F). The month sees a comparable precipitation level of 92 mm (3.6 in) over just 8 days, and humidity remains fairly steady at 71%. For more details on weather specifics in September, be sure to check out Boston weather in September.

May and October showcase distinct weather patterns, each with their own characteristics. May typically experiences a milder climate, with temperatures ranging from a minimum of 3°C (37°F) to a maximum of 31°C (89°F), resulting in an average of 14°C (58°F). Precipitation in May totals 94 mm (3.7 in) over approximately 12 days, along with a humidity level of 72%.

In contrast, October presents cooler temperatures, with a minimum of 0°C (33°F) and a maximum of 27°C (81°F), while maintaining a similar average of 14°C (57°F). However, this month sees increased rainfall, with 149 mm (5.9 in) over the same number of days, and a slightly higher humidity at 78%. For more detailed information, check out Boston weather in October.

May and November present contrasting weather patterns. In May, temperatures can range from a mild 3°C (37°F) at night to a warm 31°C (89°F) during the day, with an average temperature of 14°C (58°F). The month receives about 94 mm (3.7 in) of precipitation over 12 days, and the humidity levels sit at 72%. On the other hand, November experiences much cooler temperatures, with a minimum of -10°C (14°F) and a maximum of 22°C (72°F), averaging at 7°C (44°F). Precipitation is slightly higher at 100 mm (3.9 in) over 10 days, and the humidity increases to 84%. For more detailed information, you can check out Boston weather in November.

May and December exhibit starkly contrasting weather patterns. In May, temperatures range from a minimum of 3°C (37°F) to a pleasant average of 14°C (58°F), peaking at a warm 31°C (89°F). The month sees about 94 mm (3.7 in) of precipitation over approximately 12 days, with humidity around 72%. In contrast, December experiences much colder conditions, with temperatures dropping to a minimum of -16°C (3°F) and an average of just 2°C (36°F). The maximum temperature reaches 17°C (62°F), while precipitation increases to 124 mm (4.9 in) over 10 days, accompanied by higher humidity levels of 81%. For those interested in a detailed overview of winter weather, check out Boston weather in December.

Compare Boston's Climate with Cities Worldwide

Conclusion: What to Expect From May Weather in Boston

May in Boston marks a transitional phase from the chill of early spring to the warmth of summer. While temperatures are on the rise, reaching comfortable highs, they also fluctuate more dramatically compared to the steadiness of summer months. With an average temperature of 14°C (58°F), residents experience a refreshing blend of mild warmth and brisk cooler days. Precipitation is relatively frequent, with about 12 rainy days, contributing to the overall humidity that hovers around 72%. This combination fosters a beautiful burst of greenery and vibrant blooms, making May a uniquely dynamic time to explore the city. For a deeper dive into Boston's weather patterns, check out Boston Climate.