Climate and monthly weather forecastRock Island, WA
Climate and monthly weather forecast
Weather in January
January, the same as December, is a wintry winter month in Rock Island, Washington, with an average temperature fluctuating between 33.1°F (0.6°C) and 21.6°F (-5.8°C). Rock Island starts January with an average high-temperature of a still cold 33.1°F (0.6°C), a minor shift from December's 32.4°F (0.2°C). Weather in January »Weather in February
The last month of the winter, February, is also an icy month in Rock Island, Washington, with an average temperature fluctuating between 36.3°F (2.4°C) and 24.1°F (-4.4°C). January's transformation into February witnesses an average high-temperature of a still wintry 36.3°F (2.4°C), noting a minor change from the preceding month. Weather in February »Weather in March
The first month of the spring, March, is a chilly month in Rock Island, Washington, with temperature in the range of an average high of 45.3°F (7.4°C) and an average low of 29.7°F (-1.3°C). Rock Island sees an increase in the average high-temperature with the arrival of March, moving from February's icy 36.3°F (2.4°C) to a frosty 45.3°F (7.4°C). Weather in March »Weather in April
April is a refreshing spring month in Rock Island, Washington, with temperature in the range of an average high of 55.4°F (13°C) and an average low of 35.6°F (2°C). As Rock Island welcomes April, the average high-temperature sees a rise, transitioning from a chilly 45.3°F (7.4°C) in March to a moderate 55.4°F (13°C). Weather in April »Weather in May
May, the last month of the spring in Rock Island, is a comfortable month, with an average temperature ranging between max 66°F (18.9°C) and min 43.3°F (6.3°C). May's arrival signals an increase in average high-temperatures, moving from April's mild 55.4°F (13°C) to a still refreshing 66°F (18.9°C). Weather in May »Weather in June
June, the first month of the summer in Rock Island, is an agreeable month, with an average temperature ranging between max 73°F (22.8°C) and min 48.2°F (9°C). Rock Island's transition into June is noticed by a slight rise in the average high-temperature, advancing from a comfortable 66°F (18.9°C) in May to an agreeable 73°F (22.8°C). Weather in June »Weather in July
July is a warm summer month in Rock Island, Washington, with an average temperature ranging between max 83.1°F (28.4°C) and min 55.4°F (13°C). During the warmest month, July, temperatures average a high of 83.1°F (28.4°C) and a low of 55.4°F (13°C). The heat index for July is computed to be 82.4°F (28°C). Weather in July »Weather in August
The last month of the summer, August, is another warm month in Rock Island, Washington, with an average temperature ranging between max 82.9°F (28.3°C) and min 56.3°F (13.5°C). The introduction of August notes a subtle temperature variation to a still moderately hot 82.9°F (28.3°C) from July's 83.1°F (28.4°C). Weather in August »Weather in September
The first month of the autumn, September, is still a pleasant month in Rock Island, Washington, with an average temperature fluctuating between 71.6°F (22°C) and 49.6°F (9.8°C). In Rock Island, the average high-temperature in September decreases from a moderately hot 82.9°F (28.3°C) in August to an agreeable 71.6°F (22°C). Weather in September »Weather in October
October, like September, is another mild autumn month in Rock Island, Washington, with an average temperature ranging between min 39.7°F (4.3°C) and max 55.9°F (13.3°C). The shift into October is characterized by a noticeable reduction in the average high-temperature, decreasing from September's agreeable 71.6°F (22°C) to a refreshing 55.9°F (13.3°C). Weather in October »Weather in November
The last month of the autumn, November, is also an icy month in Rock Island, Washington, with an average temperature varying between 41.7°F (5.4°C) and 29.8°F (-1.2°C). In Rock Island, entering November brings a temperature decrement, reducing from October's mild 55.9°F (13.3°C) to a wintry 41.7°F (5.4°C). Weather in November »Weather in December
The first month of the winter, December, is also an icy month in Rock Island, Washington, with an average temperature ranging between min 20.7°F (-6.3°C) and max 32.4°F (0.2°C). The coldest time of the year is December, with temperatures averaging a high of 32.4°F (0.2°C) and a low of 20.7°F (-6.3°C). Weather in December »Updated: Jun 13, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
The most humid month is January, with an average relative humidity of 88%.
The wettest months are January and December, with an average 1.57" (40mm) of rainfall.
In Rock Island, during the entire year, the rain falls for 111.7 days and collects up to 10.71" (272mm) of precipitation.
Months with snowfall are January through April, September, November and December.
In Rock Island, during the entire year, snow falls for 31.6 days and aggregates up to 18.86" (479mm) of snow.
January has the least sunshine of the year, with an average of 4.7h of sunshine.
The months with the lowest UV index are January, February, November and December, with an average maximum UV index of 2.
On Sunday, March 10. 2024, at 2:00 am, Daylight Saving Time starts, and the time zone changes from PST to PDT. Daylight Saving Time ends Sunday, November 3. 2024, at 2:00 am, and the time zone reverts from PDT to PST.
In Rock Island, snow does not fall in May through August and October.
June has the longest days of the year, with an average of 15h and 54min of daylight.
July is the month when Rock Island sees the average highest temperatures, with a high of 83.1°F (28.4°C) and a low of 55.4°F (13°C).
The months with the lowest humidity are July and August, with an average relative humidity of 44%.
July and August are months with the least rain when the rain falls for 4.2 days and typically aggregates up to 0.24" (6mm) of rain.
The month with the highest UV index is July, with an average maximum UV index of 6.
August has the most sunshine of the year, with an average of 12.1h of sunshine.
Rock Island witnesses the coldest weather in December, with temperatures averaging a high of 32.4°F (0.2°C) and a low of 20.7°F (-6.3°C).
December is the month with the most snowfall in Rock Island. Snow falls for 9.5 days and accumulates 5.98" (152mm) of snow.
The month with the shortest days in Rock Island, Washington, is December, with an average of 8h and 30min of daylight.
Average temperature
Rock Island, WA
The warmest month (with the highest average high temperature) is July (83.1°F).
The month with the lowest average high temperature is December (32.4°F).
The month with the highest average low temperature is August (56.3°F).
The coldest month (with the lowest average low temperature) is December (20.7°F).
Average pressure
Rock Island, WA
- Average pressure in January:
30.15"Hg - Average pressure in February:
30.09"Hg - Average pressure in March:
30.01"Hg - Average pressure in April:
30"Hg - Average pressure in May:
29.96"Hg - Average pressure in June:
29.94"Hg
- Average pressure in July:
29.95"Hg - Average pressure in August:
29.93"Hg - Average pressure in September:
29.97"Hg - Average pressure in October:
30.03"Hg - Average pressure in November:
30.07"Hg - Average pressure in December:
30.14"Hg
The month with the highest atmospheric pressure is January (30.15"Hg).
The month with the lowest atmospheric pressure is August (29.93"Hg).
Average wind speed
Rock Island, WA
- Average wind speed in January:
3.8mph - Average wind speed in February:
4.3mph - Average wind speed in March:
5mph - Average wind speed in April:
6.1mph - Average wind speed in May:
6mph - Average wind speed in June:
6.5mph
- Average wind speed in July:
6.3mph - Average wind speed in August:
5.9mph - Average wind speed in September:
5.4mph - Average wind speed in October:
4.7mph - Average wind speed in November:
4.3mph - Average wind speed in December:
3.7mph
The windiest month (with the highest average wind speed) is June (6.5mph).
The calmest month (with the lowest average wind speed) is December (3.7mph).
Average humidity
Rock Island, WA
The month with the highest relative humidity is January (88%).
The months with the lowest relative humidity are July and August (44%).
Average rainfall
Rock Island, WA
- Average rainfall in January:
1.57" - Average rainfall in February:
1.02" - Average rainfall in March:
1.18" - Average rainfall in April:
0.67" - Average rainfall in May:
1.18" - Average rainfall in June:
0.47"
- Average rainfall in July:
0.24" - Average rainfall in August:
0.24" - Average rainfall in September:
0.59" - Average rainfall in October:
0.98" - Average rainfall in November:
0.98" - Average rainfall in December:
1.57"
The wettest months (with the highest rainfall) are January and December (1.57").
The driest months (with the least rainfall) are July and August (0.24").
Average rainfall days
Rock Island, WA
- Average rainfall days in January:
11.2 days - Average rainfall days in February:
11.3 days - Average rainfall days in March:
13.8 days - Average rainfall days in April:
11.8 days - Average rainfall days in May:
10.8 days - Average rainfall days in June:
6.1 days
- Average rainfall days in July:
4.2 days - Average rainfall days in August:
3.8 days - Average rainfall days in September:
6 days - Average rainfall days in October:
11.1 days - Average rainfall days in November:
11.9 days - Average rainfall days in December:
9.7 days
The month with the highest number of rainy days is March (13.8 days).
The month with the least rainy days is August (3.8 days).
Average snowfall
Rock Island, WA
The month with the highest snowfall is December (5.98").
The months with the least snowfall are May, June, July, August and October (0").
Average snowfall days
Rock Island, WA
- Average snowfall days in January:
7.8 days - Average snowfall days in February:
7.2 days - Average snowfall days in March:
3.5 days - Average snowfall days in April:
0.4 days - Average snowfall days in May:
0 days - Average snowfall days in June:
0 days
- Average snowfall days in July:
0 days - Average snowfall days in August:
0 days - Average snowfall days in September:
0.1 days - Average snowfall days in October:
0 days - Average snowfall days in November:
3.1 days - Average snowfall days in December:
9.5 days
The month with the highest number of snowfall days is December (9.5 days).
The months with the least snowfall days are May, June, July, August and October (0 days).
Average daylight / Average sunshine
Rock Island, WA
- Average daylight in January:
9h and 0min - Average daylight in February:
10h and 18min - Average daylight in March:
12h and 0min - Average daylight in April:
13h and 42min - Average daylight in May:
15h and 6min - Average daylight in June:
15h and 54min
- Average daylight in July:
15h and 30min - Average daylight in August:
14h and 12min - Average daylight in September:
12h and 30min - Average daylight in October:
10h and 48min - Average daylight in November:
9h and 18min - Average daylight in December:
8h and 30min
The month with the longest days is June (Average daylight: 15h and 54min).
The month with the shortest days is December (Average daylight: 8h and 30min).
- Average sunshine in January:
4h and 42min - Average sunshine in February:
5h and 18min - Average sunshine in March:
7h and 48min - Average sunshine in April:
10h and 30min - Average sunshine in May:
11h and 0min - Average sunshine in June:
11h and 42min
- Average sunshine in July:
12h and 0min - Average sunshine in August:
12h and 6min - Average sunshine in September:
10h and 48min - Average sunshine in October:
6h and 36min - Average sunshine in November:
5h and 54min - Average sunshine in December:
4h and 54min
The month with the most sunshine is August (Average sunshine: 12h and 6min).
The month with the least sunshine is January (Average sunshine: 4h and 42min).
Average sunshine days
Rock Island, WA
- Average sunshine days in January:
14.5 days - Average sunshine days in February:
12.6 days - Average sunshine days in March:
13.5 days - Average sunshine days in April:
15.8 days - Average sunshine days in May:
18.1 days - Average sunshine days in June:
22.2 days
- Average sunshine days in July:
25.5 days - Average sunshine days in August:
25.4 days - Average sunshine days in September:
22.2 days - Average sunshine days in October:
18.5 days - Average sunshine days in November:
14.3 days - Average sunshine days in December:
15.7 days
The month with the most sunshine days is July (25.5 days).
The month with the least sunshine days is February (12.6 days).
Average UV index
Rock Island, WA
The month with the highest UV index is July (UV index 6).
The months with the lowest UV index are January, February, November and December (UV index 2).
Average cloud cover
Rock Island, WA
The month with the most cloud cover is January (Cloud cover 49).
The months with the least cloud cover are July and August (Cloud cover 11).
Average visibility
Rock Island, WA
The months with the highest visibility are March, April, May, June, July, August, September, October and November (6mi).
The months with the lowest visibility are January and December (4mi).
