Climate and monthly weather forecastSun Valley, ID
Climate and monthly weather forecast
The climate of Sun Valley
Located in Idaho, USA, Sun Valley boasts a predominantly Subartic, subalpine climate, according to the Köppen climate classification, which categorizes it as a Dsc climate. This classification manifests in marked seasonal changes characterizing the weather conditions throughout the year.A broad analysis of the climate parameters reveals seasonal extremes in weather. The high yearly temperature fluctuates from 26.8°F (-2.9°C) in January to 74.1°F (23.4°C) in July, while the lowest temperature changes from 8.4°F (-13.1°C) in January to 50.5°F (10.3°C) in July and August. The relative humidity follows a similar trend, starting from 85% in January, dipping to 37% in August, before rising to 84% at the end of the year in December.
The area sees a fair amount of precipitation throughout the year, with rainfall ranging from 0.43" (11mm) in July to 2.01" (51mm) in March. Snowfall is significant from December till February, with the peak in February at 15" (381mm). An interesting aspect of Sun Valley's weather is its sunshine duration, broad daylight lasts between 9 hours in December to 15.4 hours in June, and the number of sunshine days varies from 15.8 days in December to 20.8 days in July.
The best time to visit Sun Valley
Records of Sun Valley's climate conditions suggest that the most favorable time to visit would be from June to August. During these summer months, the temperatures range from a comfortable 62.4°F (16.9°C) to a warm 74.1°F (23.4°C). Coupled with the relatively low humidity (from 37% to 55%), these conditions afford pleasant weather for outdoor activities. The daylight lasts around 15 hours, providing ample time for sightseeing and exploration. Rainfall is also at its lowest during these months, amounting to less than an inch, adding to the appeal of this period for visitors.The worst time to visit Sun Valley
Based on the climatological patterns, the least favorable period to visit Sun Valley would be from December to February. This period sees harsh winter conditions, with temperatures dropping as low as 8.4°F (-13.1°C) and peaking at a chilly 26.8°F (-2.9°C). Snowfall during these months is significant, with figures going up to 15" (381mm) in February. Additionally, the area is enveloped by the relative humidity levels of up to 85%, making the weather cold and damp. Daylight during this period is also limited to around 9 hours, thus restricting outdoor activities.Spring weather in Sun Valley
Spring in Sun Valley, from March to May, is marked by a considerable increase in temperature from 32.2°F (0.1°C) to 51.4°F (10.8°C). Rainfall during this season is relatively high, with an average of 1.76" (45mm) spread across 12.7 days. The amount of snowfall, however, decreases markedly from 12.56" (319mm) in March to 1.46" (37mm) in May. The average hours of daylight increase from 12 in March to 14.7 in May, presenting a good amount of daylight for outdoor activities such as hiking and bird watching.Summer weather in Sun Valley
Summer is the most pleasant season in Sun Valley, with temperatures ranging from 51.4°F (10.8°C) in May to a high of 74.1°F (23.4°C) in July. The weather remains dry, with humidity levels dropping to 38% in July from 55% in June. Rainfall also drops to an annual low of 0.43" (11mm) in July. Meanwhile, the long daylight hours, from 15.4 hours in June, gradually decrease to 13.9 hours by August.Autumn weather in Sun Valley
Autumn in Sun Valley introduces cooler temperatures, ranging from a high of 63.7°F (17.6°C) in September to 34.7°F (1.5°C) by November. The humidity increases from 44% in September to 75% in November. Rainfall during this season is moderate, increasing from 0.87" (22mm) in September to 1.1" (28mm) in November. The number of daylight hours reduces gradually from 12.5 hours in September to 9.7 hours in November.Winter weather in Sun Valley
November marks the start of the winter months in Sun Valley that sees the most severe weather with temperatures ranging from 25°F (-3.9°C) in December to 26.8°F (-2.9°C) in January. Snowfall reaches its peak during winter, with the highest at 15" (381mm) in February. Humidity levels are high, ranging between 84% and 85%. The daylight shrinks to 9 hours and the number of sunshine days is at its lowest during this time, ranging from 16.3 days in December to 15.8 days in January.Weather in January
Invigorating cold and snow characterize January's weather in Sun Valley, Idaho. The cold is most bitter this month with low temperatures plunging to 8.4°F (-13.1°C) while the highs barely reach 26.8°F (-2.9°C). Coupled with a hefty snowfall of 12.72" (323mm), Sun Valley transforms into a winter paradise. Weather in January »Weather in February
Going from January to February, Sun Valley sees a slight increase in temperatures without a substantial break from its winter persona. More snow adds another 15" (381mm) layer, earning February the title of the snowiest month of the year. Weather in February »Weather in March
March signals the start of warmer weather in Sun Valley but still retaining the winter feel. A marked distinction from February is seen in the daily highs, now reaching 32.2°F (0.1°C), with lows at 16.9°F (-8.4°C). Meanwhile, snowfall decreases to 12.56" (319mm), and the lengthening daylight hours hint at the impending spring. Weather in March »Weather in April
April marks a noticeable weather change in Sun Valley as the city begins to shake off winter's intensity. The snowfall significantly decreases to 5.83" (148mm) compared to March's 12.56" (319mm), and temperatures start climbing with the daily highs reaching a comforting 39.9°F (4.4°C). Weather in April »Weather in May
May progresses further into the spring weather in Sun Valley and sees a significant transformation from its winter scene. The accentuated warmth with highs soaring to 51.4°F (10.8°C) and lows comfortable at 32.9°F (0.5°C) puts the final end to the icy conditions. Weather in May »Weather in June
June welcomes summer into Sun Valley, drawing a stark contrast to the prior winter-chilled months. Temperatures rise dramatically from May, with daily highs elevating to a pleasant 62.4°F (16.9°C). Additionally, significant decreases in rain from 1.77" (45mm) in May to 1.22" (31mm) in June mean drier conditions. Weather in June »Weather in July
July ranks as the warmest month in Sun Valley, not only a change from June but a total departure from the city's wintry image. Temperatures peak this month with the maximum reaching a comfortable 74.1°F (23.4°C) and minimum at 50.5°F (10.3°C). Weather in July »Weather in August
Sun Valley's August weather continues in the balmy trend from July, making it another distinctly summer month. Temperatures hover around the same range with highs coming down slightly to 73.2°F (22.9°C). The sunny, less humid conditions persistence is in contrast to the dampness that characterized the spring months. Weather in August »Weather in September
September marks the onset of autumn in Sun Valley, bringing a milder and less intense heat than the preceding summer months. Temperatures fall from the highs of 73.2°F (22.9°C) in August to a more temperate 63.7°F (17.6°C). Weather in September »Weather in October
October sees a further dip in Sun Valley's weather with autumn's chill becoming more pronounced. High temperatures reduce significantly from September's 63.7°F (17.6°C) to a cooler 48°F (8.9°C) in October. The city undergoes an aesthetic transformation with fall foliage dressing up the cityscape. Weather in October »Weather in November
November in Sun Valley facilitates the transition into winter, its weather a blend of remaining autumn coolness and emerging winter chill. The dip in temperature is evident with highs falling to 34.7°F (1.5°C), quite a descent from October's 48°F (8.9°C). Weather in November »Weather in December
Rounding off the year, December sees Sun Valley fully enveloped in winter. Compared to November's transitional weather, December establishes a cold climate with highs limited to 25°F (-3.9°C) and lows dipping to 8.6°F (-13°C). Weather in December »Updated: Feb 12, 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
Throughout the year, in Sun Valley, Idaho, there are 107.7 rainfall days, and 15.63" (397mm) of precipitation is accumulated.
January through June, September through December are months with snowfall in Sun Valley.
In Sun Valley, during the entire year, snow falls for 88.2 days and aggregates up to 69.45" (1764mm) of snow.
January has the least sunshine of the year in Sun Valley, Idaho, with an average of 5.7h of sunshine.
With an average relative humidity of 87%, February is the most humid month.
The month with the most snowfall in Sun Valley, Idaho, is February, when snow falls for 15.5 days and typically aggregates up to 15" (381mm) of snow.
February is the month with the lowest UV index in Sun Valley, Idaho, with an average maximum UV index of 1.
March is the month with the most rainfall. Rain falls for 11.4 days and accumulates 2.01" (51mm) of precipitation.
On Sunday, March 10. 2024, at 2:00 am, Daylight Saving Time starts, and the time zone changes from MST to MDT. Daylight Saving Time ends Sunday, November 3. 2024, at 2:00 am, and the time zone reverts from MDT to MST.
With an average of 15h and 24min of daylight, June has the longest days of the year.
The months with the highest UV index are June and July, with an average maximum UV index of 5.
July, noted for its average high-temperature of 74.1°F (23.4°C) and an average low-temperature of 50.5°F (10.3°C), is considered the warmest month in Sun Valley, Idaho.
July is the month with the least rainfall in Sun Valley, Idaho. Rain falls for 5.9 days and accumulates 0.43" (11mm) of precipitation.
July and August are months without snowfall in Sun Valley.
With an average of 12h of sunshine, July has the most sunshine of the year in Sun Valley.
The least humid month is August, with an average relative humidity of 37%.
December is the coldest month, with the temperature often reaching an average high of 25°F (-3.9°C) and an average low of 8.6°F (-13°C).
December has the shortest days of the year, with an average of 9h and 0min of daylight.
Average temperature
Sun Valley, ID
The warmest month (with the highest average high temperature) is July (74.1°F).
The month with the lowest average high temperature is December (25°F).
The months with the highest average low temperature are July and August (50.5°F).
The coldest month (with the lowest average low temperature) is January (8.4°F).
Average pressure
Sun Valley, ID
- Average pressure in January:
30.27"Hg - Average pressure in February:
30.15"Hg - Average pressure in March:
30.06"Hg - Average pressure in April:
29.97"Hg - Average pressure in May:
29.91"Hg - Average pressure in June:
29.89"Hg
- Average pressure in July:
29.92"Hg - Average pressure in August:
29.92"Hg - Average pressure in September:
29.95"Hg - Average pressure in October:
30.05"Hg - Average pressure in November:
30.15"Hg - Average pressure in December:
30.24"Hg
The month with the highest atmospheric pressure is January (30.27"Hg).
The month with the lowest atmospheric pressure is June (29.89"Hg).
Average wind speed
Sun Valley, ID
- Average wind speed in January:
4.5mph - Average wind speed in February:
5.2mph - Average wind speed in March:
5.5mph - Average wind speed in April:
5.9mph - Average wind speed in May:
5.8mph - Average wind speed in June:
6.2mph
- 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:
5.2mph - Average wind speed in November:
4.8mph - Average wind speed in December:
4.7mph
The windiest month (with the highest average wind speed) is July (6.3mph).
The calmest month (with the lowest average wind speed) is January (4.5mph).
Average humidity
Sun Valley, ID
The month with the highest relative humidity is February (87%).
The month with the lowest relative humidity is August (37%).
Average rainfall
Sun Valley, ID
- Average rainfall in January:
1.57" - Average rainfall in February:
1.93" - Average rainfall in March:
2.01" - Average rainfall in April:
1.5" - Average rainfall in May:
1.77" - Average rainfall in June:
1.22"
- Average rainfall in July:
0.43" - Average rainfall in August:
0.51" - Average rainfall in September:
0.87" - Average rainfall in October:
1.06" - Average rainfall in November:
1.1" - Average rainfall in December:
1.65"
The wettest month (with the highest rainfall) is March (2.01").
The driest month (with the least rainfall) is July (0.43").
Average rainfall days
Sun Valley, ID
- Average rainfall days in January:
6.2 days - Average rainfall days in February:
7.4 days - Average rainfall days in March:
11.4 days - Average rainfall days in April:
11.9 days - Average rainfall days in May:
14.8 days - Average rainfall days in June:
11.5 days
- Average rainfall days in July:
5.9 days - Average rainfall days in August:
6.5 days - Average rainfall days in September:
8.8 days - Average rainfall days in October:
9.3 days - Average rainfall days in November:
7 days - Average rainfall days in December:
7 days
The month with the highest number of rainy days is May (14.8 days).
The month with the least rainy days is July (5.9 days).
Average snowfall
Sun Valley, ID
- Average snowfall in January:
12.72" - Average snowfall in February:
15" - Average snowfall in March:
12.56" - Average snowfall in April:
5.83" - Average snowfall in May:
1.46" - Average snowfall in June:
0.2"
The month with the highest snowfall is February (15").
The months with the least snowfall are July and August (0").
Average snowfall days
Sun Valley, ID
- Average snowfall days in January:
14.1 days - Average snowfall days in February:
15.5 days - Average snowfall days in March:
16 days - Average snowfall days in April:
10.6 days - Average snowfall days in May:
2.8 days - Average snowfall days in June:
0.7 days
- Average snowfall days in July:
0 days - Average snowfall days in August:
0 days - Average snowfall days in September:
0.5 days - Average snowfall days in October:
3.4 days - Average snowfall days in November:
10.6 days - Average snowfall days in December:
14 days
The month with the highest number of snowfall days is March (16 days).
The months with the least snowfall days are July and August (0 days).
Average daylight / Average sunshine
Sun Valley, ID
- Average daylight in January:
9h and 24min - Average daylight in February:
10h and 30min - Average daylight in March:
12h and 0min - Average daylight in April:
13h and 30min - Average daylight in May:
14h and 42min - Average daylight in June:
15h and 24min
- Average daylight in July:
15h and 6min - Average daylight in August:
13h and 54min - Average daylight in September:
12h and 30min - Average daylight in October:
11h and 0min - Average daylight in November:
9h and 42min - Average daylight in December:
9h and 0min
The month with the longest days is June (Average daylight: 15h and 24min).
The month with the shortest days is December (Average daylight: 9h and 0min).
- Average sunshine in January:
5h and 42min - Average sunshine in February:
6h and 24min - Average sunshine in March:
7h and 0min - Average sunshine in April:
9h and 36min - Average sunshine in May:
10h and 54min - Average sunshine in June:
11h and 36min
- Average sunshine in July:
12h and 0min - Average sunshine in August:
11h and 48min - Average sunshine in September:
9h and 24min - Average sunshine in October:
7h and 42min - Average sunshine in November:
6h and 36min - Average sunshine in December:
5h and 48min
The month with the most sunshine is July (Average sunshine: 12h and 0min).
The month with the least sunshine is January (Average sunshine: 5h and 42min).
Average sunshine days
Sun Valley, ID
- Average sunshine days in January:
16.3 days - Average sunshine days in February:
11.7 days - Average sunshine days in March:
11.3 days - Average sunshine days in April:
11.1 days - Average sunshine days in May:
12.3 days - Average sunshine days in June:
15.3 days
- Average sunshine days in July:
20.8 days - Average sunshine days in August:
20.6 days - Average sunshine days in September:
19.7 days - Average sunshine days in October:
18.2 days - Average sunshine days in November:
16.7 days - Average sunshine days in December:
15.8 days
The month with the most sunshine days is July (20.8 days).
The month with the least sunshine days is April (11.1 days).
Average UV index
Sun Valley, ID
The months with the highest UV index are June and July (UV index 5).
The month with the lowest UV index is February (UV index 1).
Average cloud cover
Sun Valley, ID
The month with the most cloud cover is February (Cloud cover 44).
The month with the least cloud cover is July (Cloud cover 10).
Average visibility
Sun Valley, ID
The months with the highest visibility are April, May, June, July, August, September, October and November (6mi).
The months with the lowest visibility are January, February and December (4mi).
