Climate - Rio Branco (Acre)

Rio Branco's climate is tropical, with a rainy season from October to April and a dry season in the austral winter, from June to August, while May and September are transitional months.
The city is the capital of the state of Acre and is located at 10 degrees south latitude, in the west of Brazil, 65 km (40 miles) away from the border with Bolivia, along the Acre River. We are in the Amazon rainforest.
The dry period, from June to August, is also the coolest at night (in fact, we are in the austral winter). From time to time, in addition, there may be cool periods due to the winds that blow from the Argentine Pampas, with highs of about 20 °C (68 °F) or even below, while at night the temperature can even reach 10 °C (50 °F).
However, from mid-August to October, the temperature rises and the hottest days of the year are recorded, before the rains.

Best Time

---

The best time to visit Rio Branco is from June to August, being the dry season. June is the best month, as July and August are more likely to be very hot.

Rio Branco - Climate data

In Rio Branco, the average temperature of the coldest month (June) is of 25.4 °C (77.8 °F), that of the warmest month (October) is of 27.8 °C (82.1 °F). Here are the average temperatures.
In Rio Branco, precipitation amounts to 2000 millimeters (78.7 inches) per year: it is therefore abundant. It ranges from 30 mm (1.2 in) in the driest month (July) to 300 mm (11.8 in) in the wettest one (February). Here is the average precipitation.
In Rio Branco, there are on average around 1750 sunshine hours per year. Here are the average hours of sunshine per day.

Rio Branco - Weather by month

Based on the period 1991-2020

---

In January, the weather in Rio Branco is usually warm to hot and muggy. The average temperature is of 27.0 °C (81 °F), with a minimum of 22.7 °C (72.9 °F) and a maximum of 31.2 °C (88.2 °F).
On the coldest nights of the month, the temperature usually drops to around 21 °C (70 °F).
On the warmest days of the month, the temperature usually reaches around 33.5 °C (92.5 °F).
Precipitation amounts to 295 mm (11.6 in), distributed over 19 days.
The day lasts on average 12 hours and 35 minutes.
There are on average 3.5 hours of sunshine per day. So, the sun shines 28% of the time.
The average humidity is 87%. Hence, the air is normally humid.
The average wind speed is 5 kph (3 mph).

---

In February, the weather in Rio Branco is usually warm to hot and muggy. The average temperature is of 26.9 °C (80 °F), with a minimum of 22.7 °C (72.8 °F) and a maximum of 31.1 °C (88 °F).
On the coldest nights of the month, the temperature usually drops to around 20.5 °C (69 °F).
On the warmest days of the month, the temperature usually reaches around 33.5 °C (92.5 °F).
Precipitation amounts to 300 mm (11.8 in), distributed over 17 days.
The day lasts on average 12 hours and 25 minutes.
There are on average 3 hours of sunshine per day. So, the sun shines 26% of the time.
The average humidity is 87%. Hence, the air is normally humid.
The average wind speed is 5 kph (3 mph).

---

In March, the weather in Rio Branco is usually warm to hot and muggy. The average temperature is of 27.0 °C (81 °F), with a minimum of 22.7 °C (72.8 °F) and a maximum of 31.3 °C (88.3 °F).
On the coldest nights, the temperature usually drops to around 20.5 °C (68.5 °F).
On the warmest days, the temperature usually reaches around 33.5 °C (92.5 °F).
Precipitation amounts to 280 mm (11 in), distributed over 17 days.
The day lasts on average 12 hours and 5 minutes.
There are on average 3.5 hours of sunshine per day. So, the sun shines 30% of the time.
The average humidity is 87%. Hence, the air is normally humid.
The average wind speed is 5 kph (3 mph).

---

In April, the weather in Rio Branco is usually warm to hot and muggy. The average temperature is of 26.9 °C (80 °F), with a minimum of 22.3 °C (72.1 °F) and a maximum of 31.4 °C (88.6 °F).
On the coldest nights, the temperature usually drops to around 18.5 °C (65.5 °F).
On the warmest days, the temperature usually reaches around 34.5 °C (94 °F).
Precipitation amounts to 205 mm (8.1 in), distributed over 13 days.
The day lasts on average 11 hours and 55 minutes.
There are on average 4 hours of sunshine per day. So, the sun shines 36% of the time.
The average humidity is 87%. Hence, the air is normally humid.
The average wind speed is 4 kph (3 mph).

---

In May, the weather in Rio Branco is usually warm to hot and muggy. The average temperature is of 26.1 °C (79 °F), with a minimum of 21.2 °C (70.2 °F) and a maximum of 30.9 °C (87.6 °F).
On the coldest nights, the temperature usually drops to around 16.5 °C (61.5 °F).
On the warmest days, the temperature usually reaches around 33.5 °C (92.5 °F).
Precipitation amounts to 90 mm (3.5 in), distributed over 8 days.
The day lasts on average 11 hours and 35 minutes.
There are on average 5 hours of sunshine per day. So, the sun shines 43% of the time.
The average humidity is 84%. Hence, the air is normally humid.
The average wind speed is 4 kph (3 mph).

---

In June, the least warm month of the year, the weather in Rio Branco is usually warm to hot and muggy. The average temperature is of 25.4 °C (78 °F), with a minimum of 20 °C (68 °F) and a maximum of 30.9 °C (87.6 °F).
On the coldest nights, the temperature usually drops to around 15.5 °C (59.5 °F).
On the warmest days, the temperature usually reaches around 33.5 °C (92.5 °F).
Precipitation amounts to 35 mm (1.4 in), distributed over 3 days.
The day lasts on average 11 hours and 35 minutes.
There are on average 6 hours of sunshine per day. So, the sun shines 50% of the time.
The average humidity is 82%. Hence, the air is normally humid.
The average wind speed is 4 kph (3 mph).

---

In July, the weather in Rio Branco is usually warm to hot and muggy. The average temperature is of 25.5 °C (78 °F), with a minimum of 19 °C (66.3 °F) and a maximum of 32 °C (89.5 °F).
On the coldest nights of the month, the temperature usually drops to around 13.5 °C (56 °F).
On the warmest days of the month, the temperature usually reaches around 35 °C (95.5 °F).
Precipitation amounts to 30 mm (1.2 in), distributed over 3 days.
The day lasts on average 11 hours and 35 minutes.
There are on average 7 hours of sunshine per day. So, the sun shines 61% of the time.
The average humidity is 75%. Hence, the air is normally humid.
The average wind speed is 5 kph (3 mph).

---

In August, the weather in Rio Branco is usually warm to hot. However, there are remarkable differences between night and day. The average temperature is of 26.8 °C (80 °F), with a minimum of 19.8 °C (67.7 °F) and a maximum of 33.7 °C (92.6 °F).
On the coldest nights of the month, the temperature usually drops to around 14 °C (57.5 °F).
On the warmest days of the month, the temperature usually reaches around 37 °C (98 °F).
Precipitation amounts to 55 mm (2.2 in), distributed over 4 days.
The day lasts on average 11 hours and 50 minutes.
There are on average 6 hours of sunshine per day. So, the sun shines 49% of the time.
The average humidity is 68%.
The average wind speed is 5 kph (3 mph).

---

In September, the weather in Rio Branco is usually very hot and muggy. The average temperature is of 27.8 °C (82 °F), with a minimum of 21.4 °C (70.5 °F) and a maximum of 34.2 °C (93.5 °F).
On the coldest nights, the temperature usually drops to around 16.5 °C (61.5 °F).
On the warmest days, the temperature usually reaches around 37 °C (98.5 °F).
Precipitation amounts to 85 mm (3.3 in), distributed over 6 days.
The day lasts on average 12 hours and 5 minutes.
There are on average 5.5 hours of sunshine per day. So, the sun shines 44% of the time.
The average humidity is 71%. Hence, the air is normally humid.
The average wind speed is 6 kph (4 mph).

---

In October, the hottest month of the year, the weather in Rio Branco is usually very hot and muggy. The average temperature is of 27.8 °C (82 °F), with a minimum of 22.3 °C (72.1 °F) and a maximum of 33.4 °C (92.1 °F).
On the coldest nights, the temperature usually drops to around 19 °C (66 °F).
On the warmest days, the temperature usually reaches around 36.5 °C (97.5 °F).
Precipitation amounts to 155 mm (6.1 in), distributed over 10 days.
The day lasts on average 12 hours and 20 minutes.
There are on average 5.5 hours of sunshine per day. So, the sun shines 43% of the time.
The average humidity is 79%. Hence, the air is normally humid.
The average wind speed is 6 kph (3 mph).

---

In November, the weather in Rio Branco is usually warm to hot and muggy. The average temperature is of 27.4 °C (81 °F), with a minimum of 22.5 °C (72.5 °F) and a maximum of 32.4 °C (90.3 °F).
On the coldest nights, the temperature usually drops to around 19.5 °C (67 °F).
On the warmest days, the temperature usually reaches around 35.5 °C (96 °F).
Precipitation amounts to 205 mm (8.1 in), distributed over 14 days.
The day lasts on average 12 hours and 35 minutes.
There are on average 4.5 hours of sunshine per day. So, the sun shines 37% of the time.
The average humidity is 83%. Hence, the air is normally humid.
The average wind speed is 6 kph (3 mph).

---

In December, the weather in Rio Branco is usually warm to hot and muggy. The average temperature is of 27.0 °C (81 °F), with a minimum of 22.6 °C (72.7 °F) and a maximum of 31.4 °C (88.5 °F).
On the coldest nights of the month, the temperature usually drops to around 20.5 °C (69 °F).
On the warmest days of the month, the temperature usually reaches around 34 °C (93 °F).
Precipitation amounts to 265 mm (10.4 in), distributed over 18 days.
The day lasts on average 12 hours and 40 minutes.
There are on average 4 hours of sunshine per day. So, the sun shines 30% of the time.
The average humidity is 86%. Hence, the air is normally humid.
The average wind speed is 6 kph (3 mph).