Last updated: August 21, 2025
December in Rio Negro, Brazil is marked by warm temperatures, with maximum highs reaching 34°C (93°F) and mild averages around 21°C (70°F). The weather can be unpredictable, as this month sees approximately 137 mm (5.4 inches) of rainfall over 17 days, contributing to the region's humid atmosphere, which averages a notable 88%. Visitors should prepare for a mix of sun and rain, making it an ideal time to explore the lush landscapes and rich biodiversity of the Amazon region.
In December, Rio Negro, Brazil, experiences a delightful transition into warmer weather, with temperatures reflecting the onset of summer. The minimum temperature hovers around 11°C (52°F), providing a mild start to the month, while the average rises to a comfortable 21°C (70°F), ideal for outdoor activities. As the days progress, the maximum temperature can soar to a sizzling 34°C (93°F), reminiscent of the tropical climate the region is known for. Compared to the cooler months earlier in the year, December's temperatures signal a shift towards heat, inviting locals and travelers alike to enjoy the lush landscapes and vibrant culture under the sun's warm embrace.
In December, Rio Negro experiences a notable increase in precipitation, with an average of 137 mm (5.4 in) of rain, marking a shift from the drier months of the year. This significant rainfall typically occurs over 17 days, providing a lush backdrop as the region transitions into the wet season. Compared to the preceding months, December's precipitation falls just shy of January's peak, reflecting the region's characteristic patterns of moisture accumulation. The relatively consistent rainfall in December, coupled with the festive atmosphere of the holiday season, enriches the natural landscape and enhances the vibrant biodiversity that Rio Negro is known for, making it an intriguing time for both residents and visitors alike.
In December, Rio Negro, Brazil, experiences an increase in humidity, reaching a comfortable 88%, the highest of the year. This month marks a notable trend where the humidity begins to rise after dipping in the mid-year months, such as July and August, which see lower levels of 80% and 79%, respectively. As the year progresses from November's 86% to December, the air becomes palpably moist, signaling the start of the warmer, more humid summer months ahead. The overall pattern reveals a consistent humidity level around 85% throughout most of the year, ensuring that Rio Negro maintains its lush, vibrant atmosphere that defines this beautiful region of Brazil.
In Rio Negro, Brazil, the UV Index remains notably high throughout the year, with December standing out as one of the months with a peak UV Index of 15, categorized as extreme. This trend follows a pattern seen from January to November, where consistently high UV levels demand vigilance from residents and beachgoers alike. March and April see a slight dip to 13 and 11, respectively, but the exposure category remains extreme during these months. As we transition into the cooler months of June and July, the UV Index drops to 6, indicating a high level of exposure, before rebounding again in August and September. The persistent high UV levels emphasize the importance of sun protection year-round. For a detailed understanding and real-time updates, please visit Rio Negro UV Index.
UV Risk Categories
In December, Rio Negro, Brazil basks in an impressive 291 hours of sunshine, marking it as the sunniest month of the year. As the year progresses, the trend shows a notable increase in daylight hours, with December emerging as a peak following a steady rise from the earlier months. After a dip in June, where sunlight dropped to just 206 hours, the region experiences a resurgence, culminating in a remarkable boost from November's 267 hours. This cheerful culmination of warmth signals not only the height of summer but also invites both locals and visitors to revel in outdoor adventures under Rio Negro's vibrant sky.
In December, Rio Negro, Brazil, experiences a 34% chance of sunny weather, marking a slight uptick from the preceding month, November, which holds a 25% likelihood. As we move towards the heart of summer, the trend suggests a gradual increase in sun-drenched days, particularly as the region transitions from the cooler months of October and November. Interestingly, July stands out with the highest chance at 53%, while the months flanking December—January and February—promise even brighter prospects with chances soaring to 12% and 43%, respectively. This emerging pattern hints that while December might not boast the sunniest days of the year, it still offers a pleasant mix of warmth and light, indicating a hopeful start to the summer season.
In Rio Negro, Brazil, the daylight duration exhibits a captivating rhythm throughout the year. Starting with January and December, the days enjoy the maximum 13 hours of daylight, signaling the height of summer. As the seasons shift towards March and April, there’s a gradual decrease to 12 hours and then to 11 hours, marking the onset of cooler months. By May and June, daylight dips to the winter minimum of 10 hours, where it remains consistently throughout July. However, as spring emerges in August, the days begin to lengthen again, restoring 11 hours of sunlight. This trend continues into the spring months of September and October, where daylight returns to 12 hours, eventually culminating back to the summer's abundant light in November and December. This cyclical pattern reflects the region's seasonal shifts, offering residents both cozy winter nights and bright, sunny days.
As December unfolds in Rio Negro, Brazil, the winds carry a gentle whisper, averaging 2.9 m/s (6 mph). This marks a notable consistency in wind patterns, as the average in December mirrors that of the preceding month, November, showcasing a steady breeze that lingers throughout the year. The transition into the summer months reveals a subtle uplift, with average winds peaking at 3.1 m/s (7 mph) in January, and recurring at similar speeds in both August and October. This trend signifies a dynamic yet predictable rhythm of nature, where the winds of December, while mild, hint at the approaching summer vigor. The slight variations across the months reflect the region's unique climatic behavior, promising a balanced and refreshing atmosphere as the year draws to a close.
Weather in Rio Negro varies notably across the year, with each month offering distinct climate conditions. This page compares December’s weather to other months in Rio Negro, focusing on differences in temperature, rainfall, humidity, and UV levels.
In December, the weather in the region features a minimum temperature of 11°C (52°F) and an average of 21°C (70°F), reaching a maximum of 34°C (93°F). The month sees a fair amount of rainfall, with precipitation totaling 137 mm (5.4 in) over 17 days, coupled with high humidity at 88%.
In contrast, January brings slightly warmer temperatures, with a minimum of 13°C (57°F), an average of 22°C (72°F), and the same maximum of 34°C (93°F). Rainfall increases to 150 mm (5.9 in) spread over 18 days, while humidity remains relatively high at 86%.
For a detailed overview of the weather patterns in January, you can refer to Rio Negro weather in January.
December and February share similar temperature ranges, with both months experiencing a minimum of around 11°C (52°F), an average of about 21°C (70°F), and a maximum reaching up to 34°C (94°F). However, December tends to be wetter, receiving 137 mm (5.4 in) of precipitation over 17 days compared to February's 124 mm (4.9 in) over 15 days. Additionally, February generally experiences lower humidity levels at 83%, compared to December's higher humidity of 88%. For more detailed information, check out Rio Negro weather in February.
In comparing the weather conditions of December and March, both months exhibit pleasant average temperatures around 21°C (70°F). December experiences slightly warmer maximum temperatures, peaking at 34°C (93°F), while March's maximum reaches 32°C (89°F). Precipitation is more pronounced in December, with 137 mm (5.4 in) over 17 days, compared to March's 109 mm (4.3 in) over 15 days. Humidity levels remain relatively high in both months, with December at 88% and March slightly lower at 85%. For more detailed information on March weather, you can refer to this link: Rio Negro weather in March.
December and April showcase contrasting weather conditions. December is notably warmer, with temperatures ranging from a minimum of 11°C (52°F) to a maximum of 34°C (93°F), resulting in an average of 21°C (70°F). This month also experiences substantial rainfall, with 137 mm (5.4 in) spread over 17 days and high humidity at 88%. In contrast, April brings cooler temperatures, with a minimum of 4°C (39°F) and a maximum of 30°C (86°F), averaging at 18°C (65°F). Precipitation in April is significantly lower, at 47 mm (1.9 in) over just 5 days, alongside a slightly lower humidity level of 85%. For more detailed information on weather patterns in April, you can check Rio Negro weather in April.
In December, the weather tends to be significantly warmer compared to May, with temperatures ranging from a minimum of 11°C (52°F) to a maximum of 34°C (93°F), yielding an average of 21°C (70°F). December also sees more precipitation, averaging 137 mm (5.4 in) over 17 days, coupled with high humidity levels of 88%. In contrast, May experiences cooler temperatures, with a minimum of 2°C (35°F) and a maximum of 28°C (83°F), leading to an average of 16°C (61°F). Precipitation in May is lower at 87 mm (3.4 in) spread over only 8 days, while humidity is slightly less at 86%. For a detailed look at May weather in Rio Negro, visit Rio Negro weather in May.
When comparing December and June weather, December experiences much warmer temperatures, with a minimum of 11°C (52°F) and a maximum of 34°C (93°F), leading to a higher average of 21°C (70°F). In contrast, June's temperatures are cooler, ranging from a minimum of 1°C (33°F) to a maximum of 26°C (79°F), resulting in a lower average of 15°C (59°F). Precipitation in December is slightly higher at 137 mm (5.4 in) over 17 days, compared to June's 118 mm (4.6 in) over just 10 days. Humidity levels are similar, with December at 88% and June at 85%. For more detailed information on June weather, you can visit Rio Negro weather in June.
In December, the weather is considerably warmer with temperatures ranging from a minimum of 11°C (52°F) to a maximum of 34°C (93°F), accompanied by high humidity at 88%. This month receives significant rainfall, with an average of 137 mm (5.4 in) spread over 17 days, making it a quite wet period. In contrast, July presents a cooler climate with temperatures fluctuating between -4°C (26°F) and 26°C (79°F), along with low precipitation at just 27 mm (1.0 in) over 4 days and a humidity level of 80%. This stark contrast highlights the seasonal variability, where December is humid and rainy, while July is crisp and relatively dry. For more detailed information about July's weather, you can visit Rio Negro weather in July.
When comparing the weather in December and August, it’s evident that December is much warmer and more humid. December temperatures range significantly, with a minimum of 11°C (52°F) and a maximum of 34°C (93°F), averaging 21°C (70°F), while August experiences cooler temperatures, with a minimum of -1°C (30°F) and a maximum of 30°C (87°F), averaging 15°C (59°F). Additionally, December sees more precipitation, totaling 137 mm (5.4 in) over 17 days, compared to August's 79 mm (3.1 in) over just 7 days. The humidity is also notably higher in December at 88% versus August's 79%. For a closer look at August weather in the region, you can visit Rio Negro weather in August.
December generally experiences warmer weather than September, with average temperatures ranging from a minimum of 11°C (52°F) to a maximum of 34°C (93°F), compared to September's range of 5°C (42°F) to 32°C (90°F). While both months see some precipitation, December is significantly wetter, receiving 137 mm (5.4 in) over 17 days, whereas September has only 69 mm (2.7 in) across 8 days. Humidity levels are also higher in December at 88%, compared to September's 82%, making the air feel more humid and warm. For a detailed look at the weather, you can check this Rio Negro weather in September.
In comparing the weather between October and December, we see some notable contrasts. December features a higher minimum temperature of 11°C (52°F) compared to October's 6°C (44°F), contributing to an average temperature of 21°C (70°F). Both months can reach a maximum of 34°C (93°F), but December typically experiences slightly more precipitation at 137 mm (5.4 in) over 17 days, while October has 147 mm (5.8 in) spread across 14 days. Additionally, December's humidity is higher at 88%, surpassing October's 82%, indicating a more humid and warm atmosphere. For a detailed look at October's climate, you can visit Rio Negro weather in October.
In comparing the weather between December and November, December tends to be slightly warmer overall, with average temperatures reaching around 21°C (70°F) compared to November's 19°C (67°F). The maximum temperatures in December can soar to 34°C (93°F), while November's peak is 31°C (89°F). Additionally, December experiences more precipitation, with 137 mm (5.4 in) over 17 days, compared to November's 103 mm (4.1 in) over 13 days. Humidity levels are also a bit elevated in December at 88%, while November sits at 86%. For more detailed information, you can check Rio Negro weather in November.
As December arrives in Rio Negro, it brings a noticeable shift in weather patterns, contrasting sharply with the cooler months preceding it. With temperatures reaching pleasant highs, the city experiences a vibrant warmth that makes outdoor activities inviting. However, don't forget your umbrella, as December is also marked by increased precipitation and higher humidity, creating a lush and vibrant landscape. This month can be quite dynamic, combining heat with occasional rainfall, an enchanting mix that highlights Rio Negro's tropical charm. For those looking to understand more about these weather nuances throughout the year, explore Rio Negro Climate.