Climate and monthly weather forecastLewiston, ID
Climate and monthly weather forecast
The climate of Lewiston
Lewiston, Idaho, positioned within the climatic zone defined by the Köppen classification as Mediterranean warm summer (Csb), experiences rather mild and comfortable weather throughout the year. The yearly averages indicate a significant fluctuation in temperature, mirroring the changing seasons. Here, the mercury soars to an annual high of 85.3°F (29.6°C) in the peak summer months while plummeting to a chilly low of 24.4°F (-4.2°C) in the frigid winter months.Humidity spans from 38% in August to a saturated 84% in January, indicating a clear contrast between the arid summer and humid autumn and winter. Rainfall displays a similar disparity, with January seeing the heaviest showers at 1.77" (45mm) compared to a somewhat arid 0.31" (8mm) in August. Snowfall, on the other hand, registers its peak in January and February with 2.56" (65mm) while staying absent from May through October.
Lewiston's sunny charm is most evident amid the long summer daylight hours, reaching a stretch of 15.8 hours in June, though sunshine hours peak at 12 in July and August. The UV index likewise peaks at 7 in July, necessitating protective measures during outdoor activities. Interestingly, despite seasonal fluctuations in other weather parameters, atmospheric pressure and visibility show little month-to-month variation.
The best time to visit Lewiston
Weather-wise, the best period to travel to Lewiston depends largely on the preferred activities of visitors. However, considering the climatic averages, the summer months, from June to August can be considered ideal. During this period, the mean temperatures hover around 71.8°F (22.1°C) to 85.3°F (29.6°C), perfect for exploring the outdoor beauty of Lewiston. Rainfall is also at its lowest, averaging between 0.31" (8mm) to 0.39" (10mm), and accompanied by 15.4 to 15.8 hours of daylight which makes it absolutely splendid for various excursions.The worst time to visit Lewiston
Winters, spanning December to February, may prove somewhat challenging for visits due to the frigid temperatures that drop down to between 24.4°F (-4.2°C) to 37.4°F (3°C). This is complemented by substantial snowfall of 0.55" (14mm) to 3.27" (83mm). The shorter daylight hours, between 8.7 to 10.4, coupled with reduced visibility, might deter visitors who prefer outdoor activities, making this period less desirable for travel.Spring weather in Lewiston
Spring in Lewiston is seen from March to May with temperatures rising smoothly from 48.6°F (9.2°C) at the start to 65.1°F (18.4°C) towards the end of the season. Humidity and rainfall decrease gradually during this period, signaling the transition towards a dryer season. Sunshine hours extend from 7.1 hours to 10.6 hours, making the days longer and ideal for outdoor activities. Despite the increasing temperatures, the UV index remains moderate, ranging from 3 to 4.Summer weather in Lewiston
The summer months from June to August in Lewiston are typically warm and dry. Temperatures climb steadily to reach their pinnacle at 85.3°F (29.6°C) in August. Coupled with this, rainfall dwindles to its annual lowest between 0.31" (8mm) to 0.39" (10mm), indicating arid conditions. While the daylight hours recede slightly from 15.8 efforts in June to 14.1 hours in August, the sunshine hours peak to their maximum of 12 hours in July and August, painting the city in bright, sunlit hues.Autumn weather in Lewiston
Autumn, observed from September to November, is characterized by a progressive drop in temperatures from 75°F (23.9°C) in September to 46°F (7.8°C) in November. Rainfall begins to increment from 0.39" (10mm) in September to 1.26" (32mm) by November, hinting towards the wetter winter season. The daylight hours also decrease significantly from 12.5 hours in September to 9.4 hours in November. However, despite the decreasing temperatures and shortening days, humidity levels remain quite comfortable, making autumn still an attractive season for tourists.Winter weather in Lewiston
Winter sets in Lewiston from December to February, bringing with it lower temperatures, ranging from 24.4°F (-4.2°C) to 37.4°F (3°C). This period also sees the highest precipitation in the form of cold rainfall and snow, accumulating between 1.77" (45mm) to 1.85" (47mm) of rain and experiencing between 2.1 to 8.1 days of snowfall. Daylight is limited between 8.7 to 10.4 hours and the sunshine duration dwindles to between 5.1 to 6.4 hours. Winter in Lewiston, nevertheless, offers a whole different charm to its weather-loving visitors.Weather in January
January brings the chill of winter to Lewiston, Idaho, as the coldest period settles in. The weather fluctuates from an average high of 37.4°F (3°C) to an average low of 27°F (-2.8°C). Snow is customary and tends to blanket the city, complementing the crisp chill with a pristine white landscape. Weather in January »Weather in February
Moving into February, weather conditions remain cold albeit a slight increase is observed when compared to January. The city sees its most substantial snowfall of the year, accumulating 3.27" (83mm). The lengthening of daylight hours hints at the approaching spring season. Weather in February »Weather in March
The transition of winter into spring commences in March. Compared to February, a noticeable increase in temperatures allows the accumulated snow to begin its thaw. Rainfall becomes more prevalent, transitioning from the quieter and delicate snowflakes of winter. Weather in March »Weather in April
April marks the onset of a more noticeable spring weather, bringing substantial changes when compared to the colder March. Substantial sunshine hours, around 9.7 per day on average, highlight the transition towards more favorable weather conditions. Weather in April »Weather in May
May experiences a considerable shift to welcomingly warm weather conditions in Lewiston. The rise in temperature does not bring excessive heat but rather the promise of a pleasant summer ahead. Longer daylight hours and a drop in humidity enhance the comfort level for residents. Weather in May »Weather in June
June carries the torch of the warm season, exhibiting a considerable rise in temperature from May. Lewiston records the lowest relative humidity at an average of 65%, making the days pleasant and largely free from oppressive mugginess. Weather in June »Weather in July
July showcases peak summer conditions, recording an average high temperature of 84°F (28.9°C). The extended daylight hours maximize outdoor activity time, while a slight increase in evening temperatures provides comfortable summer nights. Weather in July »Weather in August
Weather in August remains characterized by high temperatures, nearly mirroring July’s conditions. A slight difference in sunrise and sunset times sees daylight hours decreasing, hinting towards the oncoming fall. Despite being one of the driest months, with a scanty rainfall of 0.31" (8mm), the environment remains adequately hydrated due to water bodies in the region. Weather in August »Weather in September
Lewiston's September climate marks the beginning of mild autumnal conditions from the hot summer of August. Cooler temperatures begin to creep in, especially during the mornings, making the climate more bearable. The UV index starts to decline and the hours of sunshine decrease, aligning with the shortening of days. Weather in September »Weather in October
October ushers in a noticeable shift from the mild climate of September to the chillier autumn weather. The fall colors peak all over Lewiston, contrasting with the cool blue skies. Rainfall steadily increases but remains sporadic, allowing residents to enjoy crisp sunny days amid the changing leaves. Weather in October »Weather in November
In November, Lewiston witnesses the full onset of late fall, with a visible decrease in temperature from October. Temperatures dip and Lewiston experiences early winter snowfall of approx 0.55" (14mm). With the arrival of shorter days and longer nights, residents bundle up in warmer garments. Weather in November »Weather in December
Winter takes full effect in December with temperatures dropping significantly from November. The snowfall equivalent to January resumes, blanketing Lewiston in a white cover once again. Daylight is at its minimal, with imminent Christmas festivities lighting up the long and chilly nights. Weather in December »Updated: Jul 26, 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
With an average relative humidity of 84%, January is the most humid month.
Throughout the year, there are 142.4 rainfall days, and 14.21" (361mm) of precipitation is accumulated.
January through April, October through December are months with snowfall.
In Lewiston, during the entire year, snow falls for 24.2 days and aggregates up to 10.16" (258mm) of snow.
With an average of 5.1h of sunshine, January has the least sunshine of the year.
The month with the most snowfall is February, when snow falls for 6.5 days and typically aggregates up to 3.27" (83mm) of snow.
With an average maximum UV index of 1, February is the month with the lowest UV index.
March is the month with the most rainfall. Rain falls for 17.6 days and accumulates 1.85" (47mm) of precipitation.
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 Lewiston, snow does not fall in May through September.
June has the longest days of the year, with an average of 15h and 42min of daylight.
The month with the highest UV index is July, with an average maximum UV index of 7.
August tends to be the warmest month in Lewiston, with temperatures averaging a daily high of 85.3°F (29.6°C) and a low of 59.2°F (15.1°C).
The least humid month is August, with an average relative humidity of 38%.
The month with the least rainfall is August, when the rain falls for 5.2 days and typically collects 0.31" (8mm) of precipitation.
With an average of 12h of sunshine, August has the most sunshine of the year.
With average high temperatures of 36.1°F (2.3°C) and lows of 24.4°F (-4.2°C), December is the coldest month in Lewiston.
The month with the shortest days is December, with an average of 8h and 42min of daylight.
Average temperature
Lewiston, ID
The warmest month (with the highest average high temperature) is August (85.3°F).
The month with the lowest average high temperature is December (36.1°F).
The month with the highest average low temperature is August (59.2°F).
The coldest month (with the lowest average low temperature) is December (24.4°F).
Average pressure
Lewiston, ID
- Average pressure in January:
30.2"Hg - Average pressure in February:
30.11"Hg - Average pressure in March:
30.03"Hg - Average pressure in April:
30"Hg - Average pressure in May:
29.95"Hg - Average pressure in June:
29.93"Hg
- Average pressure in July:
29.93"Hg - Average pressure in August:
29.91"Hg - Average pressure in September:
29.96"Hg - Average pressure in October:
30.05"Hg - Average pressure in November:
30.11"Hg - Average pressure in December:
30.18"Hg
The month with the highest atmospheric pressure is January (30.2"Hg).
The month with the lowest atmospheric pressure is August (29.91"Hg).
Average wind speed
Lewiston, ID
- Average wind speed in January:
5.1mph - Average wind speed in February:
5.2mph - Average wind speed in March:
5.5mph - Average wind speed in April:
5.7mph - Average wind speed in May:
4.7mph - Average wind speed in June:
4.7mph
- Average wind speed in July:
4.3mph - Average wind speed in August:
4.3mph - Average wind speed in September:
4.3mph - Average wind speed in October:
4.8mph - Average wind speed in November:
5.2mph - Average wind speed in December:
5mph
The windiest month (with the highest average wind speed) is April (5.7mph).
The calmest months (with the lowest average wind speed) are July, August and September (4.3mph).
Average humidity
Lewiston, ID
The month with the highest relative humidity is January (84%).
The month with the lowest relative humidity is August (38%).
Average rainfall
Lewiston, ID
- Average rainfall in January:
1.69" - Average rainfall in February:
1.5" - Average rainfall in March:
1.85" - Average rainfall in April:
1.38" - Average rainfall in May:
1.42" - Average rainfall in June:
1.1"
- Average rainfall in July:
0.39" - Average rainfall in August:
0.31" - Average rainfall in September:
0.39" - Average rainfall in October:
1.14" - Average rainfall in November:
1.26" - Average rainfall in December:
1.77"
The wettest month (with the highest rainfall) is March (1.85").
The driest month (with the least rainfall) is August (0.31").
Average rainfall days
Lewiston, ID
- Average rainfall days in January:
14.5 days - Average rainfall days in February:
13.3 days - Average rainfall days in March:
17.6 days - Average rainfall days in April:
16.3 days - Average rainfall days in May:
13.6 days - Average rainfall days in June:
11.8 days
- Average rainfall days in July:
5.4 days - Average rainfall days in August:
5.2 days - Average rainfall days in September:
6.7 days - Average rainfall days in October:
11.6 days - Average rainfall days in November:
13.5 days - Average rainfall days in December:
12.9 days
The month with the highest number of rainy days is March (17.6 days).
The month with the least rainy days is August (5.2 days).
Average snowfall
Lewiston, ID
The month with the highest snowfall is February (3.27").
The months with the least snowfall are May, June, July, August and September (0").
Average snowfall days
Lewiston, ID
- Average snowfall days in January:
4.8 days - Average snowfall days in February:
6.5 days - Average snowfall days in March:
2.1 days - Average snowfall days in April:
0.5 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 days - Average snowfall days in October:
0.1 days - Average snowfall days in November:
2.1 days - Average snowfall days in December:
8.1 days
The month with the highest number of snowfall days is December (8.1 days).
The months with the least snowfall days are May, June, July, August and September (0 days).
Average daylight / Average sunshine
Lewiston, ID
- Average daylight in January:
9h and 6min - Average daylight in February:
10h and 24min - Average daylight in March:
12h and 0min - Average daylight in April:
13h and 36min - Average daylight in May:
15h and 0min - Average daylight in June:
15h and 42min
- Average daylight in July:
15h and 24min - Average daylight in August:
14h and 6min - Average daylight in September:
12h and 30min - Average daylight in October:
10h and 54min - Average daylight in November:
9h and 24min - Average daylight in December:
8h and 42min
The month with the longest days is June (Average daylight: 15h and 42min).
The month with the shortest days is December (Average daylight: 8h and 42min).
- Average sunshine in January:
5h and 6min - Average sunshine in February:
5h and 18min - Average sunshine in March:
7h and 6min - Average sunshine in April:
9h and 42min - Average sunshine in May:
10h and 36min - Average sunshine in June:
10h and 54min
- Average sunshine in July:
11h and 54min - Average sunshine in August:
12h and 0min - Average sunshine in September:
10h and 24min - Average sunshine in October:
7h and 18min - Average sunshine in November:
6h and 24min - Average sunshine in December:
5h and 24min
The month with the most sunshine is August (Average sunshine: 12h and 0min).
The month with the least sunshine is January (Average sunshine: 5h and 6min).
Average sunshine days
Lewiston, ID
- Average sunshine days in January:
13.7 days - Average sunshine days in February:
10.8 days - Average sunshine days in March:
10.8 days - Average sunshine days in April:
11.8 days - Average sunshine days in May:
15.3 days - Average sunshine days in June:
16.4 days
- Average sunshine days in July:
24 days - Average sunshine days in August:
23.5 days - Average sunshine days in September:
21.9 days - Average sunshine days in October:
18 days - Average sunshine days in November:
13.7 days - Average sunshine days in December:
13.3 days
The month with the most sunshine days is July (24 days).
The months with the least sunshine days are February and March (10.8 days).
Average UV index
Lewiston, ID
The month with the highest UV index is July (UV index 7).
The month with the lowest UV index is February (UV index 1).
Average cloud cover
Lewiston, ID
The month with the most cloud cover is February (Cloud cover 48).
The months with the least cloud cover are July and August (Cloud cover 12).
Average visibility
Lewiston, ID
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, February and December (5mi).
