Climate and monthly weather forecastBoise, ID

The climate of Boise

Boise, Idaho, USA, experiences a prominent Mediterranean warm-summer climate, labelled as Csb under the Köppen climate classification. Sitting along the river and foothills, the geographical position of Boise contributes to a moderate climate with four distinct seasons throughout the year.

A fluctuation in weather parameters is observed, where temperatures rise from January's 23.4°F (-4.8°C) to July's 87.8°F (31°C), indicating a diverse range of warmth. On the contrary, the temperatures dip towards December, cracking the mid-thirties. Accumulated snowfall, peaking to 6.65" (169mm) in December, and the substantial drop in daylight hours to 9 hours in December, confirm the arrival of winter.

Relatively high humidity is observed in January, at 80%, reducing to 30% by the heat of July. Rainfall reaches a zenith in March with 2.2" (56mm), progressively descending to 0.2" (5mm) in July. The lowest humidity and rainfall notably correlate to the most extensive sunlight experienced, amounting to a generous 12.1 hours per day in July. Moreover, the significant increase in UV index during summer is notable, peaking at 7 in July from a humble 2 at the beginning of the year.

The best time to visit Boise

Tourists looking to relish the warm, bright, and dry summer may consider visiting Boise from June to August. During these months, temperatures climb up to the mid-seventies°F, ushering in a pleasant climate suitable for outdoor activities. This period acquaints one with Boise's longest hours of daylight, spanning nearly 15 to 15.4 hours in June and July, with almost no snowfall. Further, the UV index hovers around 6-7, suggesting a need for sunscreen, hats, and comfortable clothing.

The worst time to visit Boise

The period between December and February could be deemed unfavorable for travel. As cold winters grip Boise, temperatures plunge to the twenties°F, experiencing a spike in snowfall, particularly 6.65" (169mm) in December. Daylight hours are at their lowermost during these months, roughly 9-10 hours per day, translating to shorter excursion times. Travel preparations would have to consider heavy clothing and gear suitable for snowy weather conditions.

Spring weather in Boise

In Boise, the onset of spring from March to May carries with it an increase in temperatures, from 48.9°F (9.4°C) in March to 67.1°F (19.5°C) in May. Rainfall and humidity levels fall between medium to high, peaking in March at 2.2" (56mm) and 68% respectively. Frequencies of rainfall lower in May, with an average of 1.46" (37mm) spread over 11 days. Longer daylight amongst blooming flora makes the city picturesque during this period.

Summer weather in Boise

Summers in Boise, from June to August, are characterized by high temperatures often above 75.7°F (24.3°C). A significant drop in rainfall and humidity levels is observed, reaching a yearly minimum of 0.2" (5mm) and 30%, respectively, in July. This period is known for extended daylight hours, rising to a high of 15.4 hours in June. Visitors can enjoy the warm months under clear, cloud-free skies, as cloud cover falls considerably, reaching the lowest value of 8% in July.

Autumn weather in Boise

Autumn months from September to November mark a gradual decrease in temperature, with September seeing an appreciable dip to 76.1°F (24.5°C) from summers high. Rainfall begins to increase and reaches 1.18" (30mm) in November. Humidity rises as July’s dry air recedes, and by November, it tallies up to 65%. Daylight hours decrease over these months, dipping to 9.7 hours by November, signaling the onset of Winter.

Winter weather in Boise

Boise's winter, stretching from December to February, witnesses the year's coldest temperatures, dropping to 23.2°F (-4.9°C) in both January and February. A drastic increase in snowfall occurs, peaking at 6.65" (169mm) in December, with snowfall days reaching a high of 9.2 days. While daylight hours remain low, typically around 9 to 10 hours, the sun's appearance is less frequent and shorter compared to other months. Despite the cold weather, persons appreciative of snow-filled landscapes might find this time enticing.

Weather in January

Boise, Idaho, starts the year quite chilly. Winter is at its prime, the sky is mostly cloudy which makes days shorter with just about nine hours of daylight. The inclement weather can make visibility slightly challenging which being at 5 miles due to icy or foggy conditions while UV index remains quite low at this time. Weather in January »

Weather in February

As Boise, Idaho moves towards welcoming spring, slight changes in the weather begin. The city begins to see a decent increase in daylight hours and gradually the temperatures begin to rise. With a decline in snowfall, rainfall slightly dominates the overall precipitation. Weather in February »

Weather in March

With March, Boise, Idaho, witnesses the spring effect. Rainfall still rules, overshadowing snowfall considerably. Noticeably, the days start to feel longer with increased sunshine and longer daylight hours. A noticeable warming can be felt as temperatures continue to increase, but these changes are gradual and do not trigger an abrupt change in the weather. Weather in March »

Weather in April

April in Boise, Idaho, brings a more pronounced spring climate. Precipitation shifts entirely from snow to rain as the season moves forward. Sunshine duration surpasses rainfall days, providing more clear and sunny days. The UV index begins to escalate but remains within fairly tolerable limits. Weather in April »

Weather in May

May marks the end of spring and the beginning of the summer in Boise, Idaho. The rise in temperatures becomes more evident with a marked increase in sunshine hours. While the season remains predominantly dry, occasional showers add a refreshing touch to the weather. Weather in May »

Weather in June

Entering summer, June experiences warm and dry weather in Boise, Idaho. The rise in temperatures is often balanced out by a marked decrease in relative humidity. Having the highest daylight duration, the city enjoys around 15.4 hours of sun. Weather in June »

Weather in July

July brings the heatwave to Boise, Idaho, with peak summer temperatures. Although it's the dry season, occasional thunderstorms can bring a rapid change in the weather. Despite being the hottest month, the comfortable wind speed makes the searing heat bearable during the day. Weather in July »

Weather in August

August sees the last phase of summer in Boise, Idaho. Despite lingering heat, slow but gradual temperature declines commence. The daylight duration decreases slightly while relative humidity doesn’t see a significant change. With increased cloud cover, the sunshine duration reduces, yet the heat continues to sustain due to lower precipitation. Weather in August »

Weather in September

September in Boise, Idaho, brings a transitional phase: summer’s end and autumn's start. The falling temperatures are evident while the humidity begins to creep up. The sky becomes less clear with increased cloud cover leading to a reduction in sunshine hours. Weather in September »

Weather in October

October brings distinct autumn vibes to Boise, Idaho. Temperatures continue to drop steadily, creating an invigorating atmosphere in the city as tree leaves take on beautiful fall colors. Cloud cover and humidity continue to increase while daylight hours become noticeably shorter. Weather in October »

Weather in November

November in Boise, Idaho, is the peak of fall, with temperatures continuing to plummet. The city begins to prepare for winter as the dry, sunny days give way to colder, rain-dominated weather. Snowfall makes its initial appearance of the season, although rainfall shares equal prominence. Weather in November »

Weather in December

The month of December introduces Boise, Idaho, to winter. Snowfall sees a significant boost, dominating overall precipitation. Falling temperatures, shorter daylight hours, and increased cloud cover underscore the typical winter environment. Weather in December »