Last updated: January 18, 2025
Gunma, Japan, experiences a diverse climate characterized by Köppen-Geiger classifications Cfa and Dfb, which denote a humid subtropical climate transitioning to a humid continental climate. Throughout the year, temperatures exhibit a wide range: minimum temperatures can plunge to -16°C (3°F) in February, while the average hovers around 13°C (56°F). The province sees its peak warmth in July, where temperatures can soar up to 38°C (100°F), providing a stark contrast to its cold winter months. This climatic variability plays a crucial role in shaping the region's unique ecosystem and agricultural practices.
Gunma, Japan, exhibits pronounced seasonal temperature fluctuations, with cold winters and hot summers defining its climate. The year begins with frigid January temperatures, dipping to a minimum of -16°C (3°F), gradually warming through February as averages reach 3°C (37°F). As spring unfolds, March and April witness a steady rise, with daytime highs peaking at 29°C (84°F) in April. May signals a transition into summer, with average temperatures soaring to 17°C (63°F) and maximums hitting 33°C (92°F). The peak of summer in July brings maximum temperatures up to 38°C (100°F), while August remains similarly warm but slightly cooler at a maximum of 37°C (99°F). As the year progresses into autumn, September sees a decline in warmth, averaging 21°C (70°F), which continues through October and November, leading back to winter with December temperatures ranging from -15°C (5°F) to 20°C (67°F). This cyclical temperature pattern emphasizes the marked contrasts between Gunma's distinct seasonal phases.
Kusatsu experiences a wide temperature range throughout the year, with January seeing minimums of -12°C (11°F) and August reaching maximums of 34°C (93°F). This variation reflects the region's diverse climate, offering a unique experience in each season. For more details on monthly temperatures in Kusatsu, visit monthly temperatures in Kusatsu.
Gunma, Japan, experiences varied precipitation levels throughout the year, aligning closely with the changing seasons. Winter months, particularly January and February, see relatively low rainfall, with averages of 59 mm (2.3 in) and 57 mm (2.2 in) respectively, typically occurring over 10 days each month. As spring approaches, precipitation increases significantly, reaching 125 mm (4.9 in) in March and peaking in April at 132 mm (5.2 in), which corresponds with the region's blossoming flora. May continues this upward trend with 151 mm (5.9 in) of rainfall, setting the stage for summer's peak moisture.
During the summer months, Gunma faces its highest precipitation levels, particularly in July, when average rainfall escalates to a substantial 297 mm (11.7 in) over approximately 24 days. Following July, August maintains significant precipitation at 193 mm (7.6 in), while September records 211 mm (8.3 in), indicating the sustenance of the wet season. Autumn further elevates monthly rainfall, especially in October with 274 mm (10.8 in), before retreating to lower levels in November and December, which average 49 mm (1.9 in) and 59 mm (2.3 in) respectively. This pattern underscores the contrast between Gunma's lush, rain-soaked seasons and the drier winter months.
In Gunma, Japan, sunshine duration exhibits a notable seasonal progression, characterized by an increase in hours from the depths of winter to the height of summer. Starting the year, January records 187 hours of sunshine, gradually rising to 233 hours in February. This upward trend continues through the spring months, with March, April, and May boasting 261, 278, and 281 hours respectively. Notably, May emerges as a peak sunshine month, reflecting the transition to warmer weather and extended daylight hours, which invigorate both the landscape and local activities.
As summer arrives, the pattern of sunshine hours holds steady before witnessing a slight dip in July to 233 hours, likely influenced by increased precipitation during the rainy season. However, August rebounds with 273 hours of sunshine, marking one of the brightest periods of the year. As the seasons shift to autumn, sunshine hours again decrease, with September recording 223 hours and October further declining to 206 hours. By November, there's a slight recovery with 226 hours, before the year concludes with 225 hours in December. This seasonal trend highlights Gunma's vibrant summer months, while also pointing to the subtler variations in sunlight that shape each season's character.
The UV Index in Gunma, Japan, varies significantly throughout the year, reflecting seasonal changes in sun exposure and intensity. Beginning in January, the index sits at 4, categorized as moderate, allowing for up to 30 minutes of unprotected sun exposure. This gradually increases in February to a UV Index of 6, with a high exposure category and a reduced burn time of 25 minutes. As spring unfolds, March sees a sharp rise to 9, qualifying as very high, and by April, it peaks at 10, indicating a continuing need for sun protection, with burn times as low as 15 minutes. The intensity remains high through May, reaching an extreme 11, necessitating vigilant sun protection throughout the month.
Entering the summer months, the UV Index remains at an extreme level of 11 from June to August, where sun exposure becomes increasingly hazardous with just 10 minutes recommended for unprotected skin. The trend slightly lessens in September as the index drops to 10, returning to very high levels. As autumn sets in, October and November see the index declining to 7 and 5 respectively, categorized as high and moderate, allowing for longer exposure times before risk increases again. December brings the UV Index down to 3, still moderate, encouraging cautious sun practices during the winter months. This seasonal pattern underscores the importance of sun safety measures, particularly during the summer's peak UV exposure periods in Gunma.
UV Risk Categories
In Gunma, Japan, daylight duration varies markedly throughout the year, showcasing the transition between the darker winter months and the brightness of summer. January begins with approximately 9 hours of daylight, gradually increasing to 10 hours in February. As spring approaches, March experiences an increase to 11 hours, followed by a significant jump in April to 13 hours. The progression continues through May, where daylight reaches 14 hours, providing ample time for outdoor activities and natural growth as the region comes alive with spring and early summer.
During the summer months, daylight duration remains consistent at 14 hours from June to July, before slightly declining to 13 hours in August as the summer wanes. As autumn sets in, daylight hours gradually decrease, starting at 12 hours in September and dropping to 11 hours in October. By November, daylight returns to 10 hours, wrapping up before another cycle begins with 9 hours in December. This cyclical pattern of daylight highlights Gunma’s seasonal shifts, influencing agriculture, recreation, and daily living as residents adapt to the rhythm of light throughout the year.
Kusatsu, Japan experiences a diverse climate characterized by cold winters and warm summers. January averages around -2°C (29°F) with significant snowfall, while July can peak at 33°C (91°F), accompanied by high humidity and rainfall, particularly in July with 278 mm (10.9 in) of precipitation. The transition months of spring and autumn provide comfortable temperatures and ample sunshine, contributing to a pleasant overall climate. For more detailed information on the weather patterns of the area, visit Kusatsu climate.
In conclusion, Gunma, Japan, presents a dynamic climate characterized by its varied temperatures, precipitation patterns, UV exposure, sunshine duration, and daylight hours throughout the year. The region's transition from cold winters to hot summers highlights significant seasonal changes that influence daily life, agriculture, and outdoor activities. With increasing daylight and sunshine in the warmer months coinciding with heightened UV indices, residents must strategically plan for sun safety. Conversely, the gradual decline in daylight and sunshine during the colder months offers a reminder of nature's cyclical rhythms. Together, these factors underscore the importance of understanding and adapting to Gunma's climate, allowing both locals and visitors to fully appreciate and navigate this vibrant region throughout the year.