Climate - Pasco (Washington_state)

The climate of Pasco is arid continental, with cold, relatively rainy winters and hot, sunny summers.
The city is part, together with Kennewick and Richland, of the so-called Tri-Cities, three cities connected to each other at the confluence of the Yakima, Snake and Columbia rivers. We are in the eastern part of the state of Washington. Since we are practically at sea level and far from the ocean, this is one of the driest areas of the state, and one of the hottest in summer.
In winter, sometimes even in November, cold waves are possible, during which the temperature can drop to -20 °C (-4 °F) or even below. The temperature dropped to -24 °C (-11 °F) in November 1985, -22.7 °C (-9 °F) in December 1990, -26.7 °C (-16 °F) in December 1996, -28.3 °C (-19 °F) in January 2004, and -23 °C (-9.5 °F) in December 2016.
Snowfall is quite frequent, but generally not abundant. On average, only 15 cm (6 in) of snow fall per year.
In summer, there are several very hot days. On the hottest days of the year, the temperature generally reaches 39/40 °C (102/104 °F), but sometimes even higher. During the exceptional heat wave of late June 2021, it reached 46 (115 °F). In August 1961, at the nearby Ice Harbor Dam, a dam on the Snake River, the highest record of Washington state was set with 48 °C (118 °F).
The average temperature of the coldest month (December) is of 1.2 °C (34.1 °F), that of the warmest month (July) is of 23.7 °C (74.7 °F). Here are the average temperatures.

Precipitation amounts to 195 millimeters (7.6 inches) per year: it is therefore at a desert level. It ranges from 5 mm (0.2 in) in the driest months (July, August) to 25 mm (1 in) in the wettest ones (January, December). Here is the average precipitation.

Best Time

The best times to visit Pasco are spring and autumn, and in particular the months of May and September, to avoid both the winter cold and the summer heat.

Back to the climate of Washington state.

Pasco - Weather by month

Based on the period 1991-2020

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In January, the weather in Pasco is usually cold. The average temperature is of 1.4 °C (35 °F), with a minimum of -2.3 °C (27.8 °F) and a maximum of 5.2 °C (41.4 °F).
On the coldest nights of the month, the temperature usually drops to around -11.5 °C (11 °F). However, it dropped to -28.3 °C (-18.9 °F) in January 2004.
On the warmest days of the month, the temperature usually reaches around 15 °C (59 °F). However, it reached 19.4 °C (66.9 °F) in January 1995.
Precipitation amounts to 25 mm (1 in), distributed over 10 days.
The day lasts on average 9 hours and 5 minutes.
The average humidity is 81%. Hence, the air is normally humid.
The average wind speed is 10 kph (6 mph).

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In February, the weather in Pasco is usually cold. The average temperature is of 3.6 °C (38 °F), with a minimum of -2.1 °C (28.2 °F) and a maximum of 9.2 °C (48.6 °F).
On the coldest nights of the month, the temperature usually drops to around -10.5 °C (13.5 °F). However, it dropped to -26.7 °C (-16.1 °F) in February 1996.
On the warmest days of the month, the temperature usually reaches around 16.5 °C (61.5 °F). However, it reached 21.1 °C (70 °F) in February 1995.
Precipitation amounts to 15 mm (0.6 in), distributed over 8 days.
The day lasts on average 10 hours and 25 minutes.
The average humidity is 74%. Hence, the air is normally humid.
The average wind speed is 10 kph (6 mph).

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In March, the weather in Pasco is usually quite mild. However, there are remarkable differences between night and day. The average temperature is of 7.7 °C (46 °F), with a minimum of 0.6 °C (33.1 °F) and a maximum of 14.8 °C (58.6 °F).
On the coldest nights, which normally occur at the beginning of the month, the temperature usually drops to around -6.5 °C (20 °F). However, it dropped to -18.3 °C (-0.9 °F) in March 2019.
On the warmest days, which normally occur at the end of the month, the temperature usually reaches around 22 °C (72 °F). However, it reached 26.7 °C (80.1 °F) in March 2003.
Precipitation amounts to 20 mm (0.8 in), distributed over 8 days.
The day lasts on average 12 hours and 0 minutes.
The average humidity is 61%.
The average wind speed is 12 kph (8 mph).

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In April, the weather in Pasco is usually mild. However, there are remarkable differences between night and day. The average temperature is of 11.5 °C (53 °F), with a minimum of 3.6 °C (38.4 °F) and a maximum of 19.4 °C (67 °F).
On the coldest nights, which normally occur at the beginning of the month, the temperature usually drops to around -3 °C (26.5 °F). However, it dropped to -6 °C (21.2 °F) in April 2008.
On the warmest days, which normally occur at the end of the month, the temperature usually reaches around 28 °C (82 °F). However, it reached 34.4 °C (93.9 °F) in April 1998.
Precipitation amounts to 15 mm (0.6 in), distributed over 7 days.
The day lasts on average 13 hours and 35 minutes.
The average humidity is 53%.
The average wind speed is 13 kph (8 mph).

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In May, the weather in Pasco is usually very mild. However, there are remarkable differences between night and day. The average temperature is of 16.3 °C (61 °F), with a minimum of 7.9 °C (46.3 °F) and a maximum of 24.7 °C (76.5 °F).
On the coldest nights, which normally occur at the beginning of the month, the temperature usually drops to around 0.5 °C (33.5 °F). However, it dropped to -2.2 °C (28 °F) in May 1999.
On the warmest days, which normally occur at the end of the month, the temperature usually reaches around 34 °C (93 °F). However, it reached 38.3 °C (100.9 °F) in May 1993.
Precipitation amounts to 20 mm (0.8 in), distributed over 7 days.
The day lasts on average 15 hours and 0 minutes. So the days are long.
The average humidity is 50%.
The average wind speed is 12 kph (8 mph).

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In June, the weather in Pasco is usually warm. However, there are remarkable differences between night and day. The average temperature is of 19.9 °C (68 °F), with a minimum of 11.4 °C (52.6 °F) and a maximum of 28.4 °C (83.1 °F).
On the coldest nights, which normally occur at the beginning of the month, the temperature usually drops to around 5.5 °C (42.5 °F). However, it dropped to 2.8 °C (37 °F) in June 2002.
On the warmest days, which normally occur at the end of the month, the temperature usually reaches around 37 °C (99 °F). However, it reached 43.9 °C (111 °F) in June 2015.
Precipitation amounts to 15 mm (0.6 in), distributed over 5 days.
The day lasts on average 15 hours and 40 minutes. So the days are long. June 21, the summer solstice, is the longest day of the year in the Northern Hemisphere.
The average humidity is 46%.
The average wind speed is 12 kph (8 mph).

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In July, the warmest month of the year, the weather in Pasco is usually warm to hot. However, there are remarkable differences between night and day. The average temperature is of 23.7 °C (75 °F), with a minimum of 13.8 °C (56.9 °F) and a maximum of 33.6 °C (92.5 °F).
On the coldest nights of the month, the temperature usually drops to around 8.5 °C (47.5 °F). However, it dropped to 5.6 °C (42.1 °F) in July 1999.
On the warmest days of the month, the temperature usually reaches around 41 °C (105.5 °F). However, it reached 45.6 °C (114.1 °F) in July 1991.
Precipitation amounts to only 5 mm (0.2 in), distributed over 2 days.
The day lasts on average 15 hours and 20 minutes. So the days are long.
The average humidity is 41%.
The average wind speed is 11 kph (7 mph).

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In August, the weather in Pasco is usually warm to hot. However, there are remarkable differences between night and day. The average temperature is of 22.9 °C (73 °F), with a minimum of 13.2 °C (55.7 °F) and a maximum of 32.6 °C (90.7 °F).
On the coldest nights of the month, the temperature usually drops to around 8 °C (46 °F). However, it dropped to 4.4 °C (39.9 °F) in August 2008.
On the warmest days of the month, the temperature usually reaches around 39.5 °C (103 °F). However, it reached 44 °C (111.2 °F) in August 1998.
Precipitation amounts to only 5 mm (0.2 in), distributed over 2 days.
The day lasts on average 14 hours and 0 minutes.
The average humidity is 44%.
The average wind speed is 10 kph (6 mph).

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In September, the weather in Pasco is usually very mild. However, there are remarkable differences between night and day. The average temperature is of 17.9 °C (64 °F), with a minimum of 8.7 °C (47.6 °F) and a maximum of 27.2 °C (80.9 °F).
On the coldest nights, which normally occur at the end of the month, the temperature usually drops to around 2.5 °C (36 °F). However, it dropped to -3 °C (26.6 °F) in September 2000.
On the warmest days, which normally occur at the beginning of the month, the temperature usually reaches around 34.5 °C (94 °F). However, it reached 38.3 °C (100.9 °F) in September 1998.
Precipitation amounts to 10 mm (0.4 in), distributed over 3 days.
The day lasts on average 12 hours and 30 minutes.
The average humidity is 52%.
The average wind speed is 9 kph (6 mph).

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In October, the weather in Pasco is usually mild. However, there are remarkable differences between night and day. The average temperature is of 11.2 °C (52 °F), with a minimum of 3.6 °C (38.4 °F) and a maximum of 18.8 °C (65.8 °F).
On the coldest nights, which normally occur at the end of the month, the temperature usually drops to around -4.5 °C (24 °F). However, it dropped to -12.8 °C (9 °F) in October 2002.
On the warmest days, which normally occur at the beginning of the month, the temperature usually reaches around 27 °C (81 °F). However, it reached 32.2 °C (90 °F) in October 1991.
Precipitation amounts to 15 mm (0.6 in), distributed over 6 days.
The day lasts on average 10 hours and 50 minutes.
The average humidity is 64%.
The average wind speed is 9 kph (6 mph).

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In November, the weather in Pasco is usually quite cold. The average temperature is of 4.9 °C (41 °F), with a minimum of -0.1 °C (31.9 °F) and a maximum of 9.9 °C (49.9 °F).
On the coldest nights, which normally occur at the end of the month, the temperature usually drops to around -8 °C (17 °F). However, it dropped to -21.7 °C (-7.1 °F) in November 2010.
On the warmest days, which normally occur at the beginning of the month, the temperature usually reaches around 20 °C (68 °F). However, it reached 25 °C (77 °F) in November 1999.
Precipitation amounts to 20 mm (0.8 in), distributed over 9 days.
The day lasts on average 9 hours and 25 minutes.
The average humidity is 76%. Hence, the air is normally humid.
The average wind speed is 10 kph (6 mph).

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In December, the coldest month of the year, the weather in Pasco is usually cold. The average temperature is of 1.2 °C (34 °F), with a minimum of -2.6 °C (27.3 °F) and a maximum of 5 °C (41 °F).
On the coldest nights of the month, the temperature usually drops to around -11.5 °C (11 °F). However, it dropped to -23 °C (-9.4 °F) in December 1996.
On the warmest days of the month, the temperature usually reaches around 15 °C (58.5 °F). However, it reached 20.6 °C (69.1 °F) in December 2015.
Precipitation amounts to 25 mm (1 in), distributed over 10 days.
The day lasts on average 8 hours and 40 minutes. December 21, the winter solstice, is the shortest day of the year in the Northern Hemisphere.
The average humidity is 81%. Hence, the air is normally humid.
The average wind speed is 10 kph (6 mph).