Last updated: February 24, 2025
August in Napa, United States, showcases ample sunshine and striking temperatures, with a scorching maximum of 42°C (108°F) that highlights the warmth of summer. The month presents an average temperature of 21°C (71°F), providing a pleasant respite for outdoor activities. Notably, residents and visitors alike enjoy zero precipitation, as the city remains dry throughout the month, complemented by a humidity level of 36% that enhances the summer atmosphere. Whether exploring vineyards or enjoying the vibrant local culture, Napa's August weather sets the stage for an unforgettable experience.
In August, Napa experiences its warmest temperatures of the year, with minimums around 12°C (53°F) and maximums peaking at 42°C (108°F). The average temperature hovers at a pleasant 21°C (71°F), creating ideal conditions for vineyard visits and outdoor festivities. This month marks a continuation of the summer heat, following the peak in July, where temperatures remain consistently high. As the season transitions into September, we can expect a slight decrease in warmth, but August’s sun-soaked days ensure that Napa remains vibrant and lively, perfect for enjoying the region’s renowned wine and picturesque landscapes.
August in Napa is characterized by a notable dry spell, as the region receives no precipitation during this month, mirroring the trend seen in July. This lack of rain is part of a broader pattern, with the peak rainfall occurring in the winter months, particularly January and February, which collectively see over 230 mm of precipitation. As temperatures rise and summer sets in, rainfall dwindles significantly, with zero precipitation days recorded from June through August. This shift towards a drier climate in the heart of summer is typical for Napa, allowing for ample sunshine and ideal conditions for the region's renowned vineyards. However, the transition into September marks a slight uptick, as even a mere 1 mm of rain hints at the potential return of moisture as the seasons change.
As summer unfolds in Napa, August marks a significant dip in humidity, reaching a low of 36%, the driest month of the year. This trend of decreasing humidity begins in May at 74% and continues through July, when it hits a mere 44%. The dry heat of August contrasts sharply with the high humidity levels typical of the winter months, where figures hover around 84% from January to March. As the year progresses, the humidity gradually rises again, starting in September and peaking once more in late fall and winter. This seasonal ebb and flow creates a unique climate, making Napa Valley not just a feast for the senses, but also a striking example of nature's rhythm.
In August, Napa experiences a very high UV Index of 10, requiring residents and visitors to remain vigilant about sun exposure, with a burn time of just 15 minutes. This pattern continues the trend observed throughout summer, where UV levels peak in June and July at an extreme 11. As the month progresses into September, the Index begins to decline slightly to 9, signaling the transition to the more moderate conditions of autumn. Notably, the UV Index fluctuates significantly throughout the year, starting at a moderate 3 in January and rising sharply to its summer highs. For detailed UV Index forecasts and safety tips, visit Napa UV Index.
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August in Napa, United States, is a breathtaking continuation of the summer sun, boasting 356 hours of glorious sunlight. This month stands out after a peak in July, which recorded 394 hours—the highest insolation of the year. Following the radiant July, August still holds strong, contributing to a vibrant backdrop for vineyards and outdoor pursuits. The trend of increasing hours from the colder months culminates in a sunny crescendo just before a gentle decline begins in September. With the sun-drenched warmth lingering, August perfectly encapsulates the essence of Napa's summer charm, inviting both visitors and locals alike to bask in its golden glow.
In Napa, the month of August boasts a 79% chance of sunny weather, making it one of the sunniest months of the year. This trend highlights a gradual increase in sunshine from the chill of January, which starts at just 38%, steadily rising through the spring with April reaching 70%. As summer unfolds, both May and June remain high at 82%, before a slight dip in July to 73%. However, August maintains a robust likelihood of clear skies, offering sun-soaked days that invite exploration of the region’s famed vineyards and outdoor activities. As summer wanes, the probability of sunny weather begins to decrease again in September, but August remains a peak period for enjoying the warm, golden rays of the California sun.
In August, Napa baskes in an inviting 13 hours of daylight, a slight decline from the peak 14 hours experienced in the summer months of June and July. This month serves as a transition, as the daylight begins to wane with the approach of fall. The extended hours of sunlight earlier in the year—starting from just 9 hours in January and steadily increasing to 14 by June—highlight the region's gradual march toward longer summer days. As August rolls in, the fading daylight hints at the cooler months ahead, yet it still offers plentiful opportunities to enjoy the picturesque vineyards and vibrant sunsets that Napa is famous for. The trend continues into September, where daylight decreases to 12 hours, reminding us of nature's cyclical rhythm as the seasons shift.
In Napa, United States, the August winds whisper at an average speed of 2.7 m/s (6 mph), reflecting a gentle shift from the peak summer breezes. As the summer months unfold, we see a gradual increase in wind speed from January's calm 2.0 m/s to a summer high of 3.3 m/s in June. However, August marks a slight retreat, returning to a more moderate pace similar to earlier months. This trend continues into September, where winds ease to 2.4 m/s (5 mph), signaling the transition toward the cooler autumn days ahead. Overall, Napa's winds throughout the year demonstrate a rhythmic oscillation, where warmth invites breezy comfort before the year begins to slow down.
The weather in Napa changes throughout the year, offering a unique experience in each season. Below is a month-by-month comparison of August's weather with other months, highlighting differences in temperature, precipitation, and other key factors. Click on each section to discover seasonal trends in Napa and find detailed weather information for every month.
August and January present starkly contrasting weather conditions. In August, temperatures soar with a minimum of 12°C (53°F) and an average of 21°C (71°F), peaking at a blistering 42°C (108°F). The month is dry, featuring no precipitation and low humidity at 36%. In contrast, January brings a chill, with temperatures ranging from a minimum of -2°C (29°F) to a maximum of 25°C (77°F) and an average of only 10°C (50°F). This winter month is also considerably wetter, with total precipitation reaching 119 mm (4.7 in) over 8 days, and humidity levels climbing to 84%. For more insights into January weather, you can visit Napa weather in January.
August and February present stark contrasts in weather conditions. August boasts warm temperatures, with averages around 21°C (71°F) and soaring highs that can reach up to 42°C (108°F), while experiencing virtually no rainfall. In sharp contrast, February features cooler temperatures, with daily averages around 11°C (53°F) and nighttime lows dipping to -1°C (30°F). Additionally, February is significantly wetter, accumulating about 113 mm (4.5 in) of precipitation over an average of seven rainy days and higher humidity levels at 84%. For more detailed insights, you can check Napa weather in February.
August and March present a stark contrast in weather conditions. In August, the temperatures soar with a minimum of 12°C (53°F) and can reach a scorching maximum of 42°C (108°F), while the average temperature settles around 21°C (71°F). The month is characterized by dry conditions, with no recorded precipitation and a lower humidity level of 36%. Conversely, March experiences much cooler temperatures, ranging from a chilly minimum of 1°C (34°F) to a warm maximum of 30°C (87°F), with an average of 12°C (55°F). This month also sees significant rainfall, totaling 81 mm (3.2 in) over 9 rainy days, along with higher humidity levels at 83%. For more detailed insights, you can check out Napa weather in March.
When comparing the weather in August and April, it’s clear that August is significantly warmer and drier. August showcases a minimum temperature of 12°C (53°F) and can soar to a scorching maximum of 42°C (108°F), with humidity at a comfortable 36% and no recorded precipitation. In contrast, April starts cooler with a minimum of 3°C (38°F), an average temperature of 15°C (60°F), and a maximum of 33°C (92°F). April also sees more moisture, with 33 mm (1.3 in) of precipitation over 5 days and much higher humidity at 81%. For more details on April's climate, check out Napa weather in April.
August weather in Napa features a warm climate with temperatures ranging from a minimum of 12°C (53°F) to a scorching maximum of 42°C (108°F) and an average of 21°C (71°F). In stark contrast, May experiences milder temperatures, with a minimum of 5°C (41°F) and a maximum of 37°C (99°F), averaging around 18°C (64°F). While August remains dry with no recorded precipitation and low humidity at 36%, May sees a bit more moisture, with 19 mm of precipitation over 2 days and significantly higher humidity at 74%. For more details, check out Napa weather in May.
In comparison to June, August typically features slightly warmer temperatures, with August recording a minimum of 12°C (53°F) and a maximum of 42°C (108°F), while June has a minimum of 10°C (51°F) and a maximum of 41°C (106°F). Both months maintain an average temperature of around 21°C (71°F). However, August stands out for its lack of precipitation, recording 0 mm, whereas June experiences a modest 2 mm of rainfall. Notably, the humidity levels also differ, with August being drier at 36% compared to the higher humidity of 64% in June. For more detailed information, you can visit Napa weather in June.
In comparing the weather between August and July, both months exhibit similar averages with minimum temperatures of 12°C (53°F) in August and 11°C (53°F) in July. However, August experiences slightly higher maximum temperatures, reaching up to 42°C (108°F), compared to July’s peak of 40°C (104°F). Both months are notably dry, recording 0 mm of precipitation and maintaining a consistent lack of rainy days. One notable difference is the humidity level, which is lower in August at 36%, compared to July's 44%. For more detailed information, you can refer to Napa weather in July.
August typically experiences warmer temperatures, with a minimum of 12°C (53°F) and a maximum reaching up to 42°C (108°F), while September starts to cool down slightly with a minimum of 8°C (46°F) but can still reach a maximum of 44°C (111°F). Both months boast low precipitation, with August recording no rainfall and September only seeing a minimal 1 mm (0.0 in), keeping conditions dry. However, humidity levels tend to rise in September to 44%, compared to August's 36%, indicating a slight increase in moisture in the air as the seasons shift. For more detailed insights, check out Napa weather in September.
August tends to be hot and dry, with temperatures reaching a peak of 42°C (108°F) and an average of 21°C (71°F). The humidity remains relatively low at 36%, and the month sees no precipitation at all. In contrast, October brings a notable shift in weather patterns; the temperatures drop significantly, with a maximum of 36°C (98°F) and an average of 18°C (65°F). This month also sees increased humidity at 65% and recorded precipitation of 29 mm (1.1 in) over two days, signaling a transition to cooler, wetter conditions. For more details on the specifics, you can visit Napa weather in October.
August and November exhibit stark contrasts in weather conditions. In August, temperatures soar, with a minimum of 12°C (53°F) and a blistering maximum reaching 42°C (108°F), while humidity is relatively low at 36% and there’s no recorded precipitation. In contrast, November sees a marked drop in temperature, with a minimum of 0°C (32°F) and an average of 13°C (56°F). Additionally, November is wetter, experiencing 43 mm (1.7 in) of precipitation over five days and significantly higher humidity at 84%. For more details on November’s climate, you can check Napa weather in November.
August and December present strikingly different weather conditions. In August, temperatures can soar, with minimums around 12°C (53°F) and maximums reaching a scorching 42°C (108°F), yet the humidity remains relatively low at 36%. The month is characterized by a dry climate, recording no precipitation. In contrast, December brings much cooler temperatures, with averages around 10°C (50°F) and maximums of 24°C (75°F). This month is also significantly wetter, with 91 mm (3.6 in) of precipitation spread over 9 days, and humidity levels rise to a high 83%. For more details on December weather, check out Napa weather in December.
August in Napa stands out with its exceptionally warm temperatures, boasting a maximum heat that can reach up to a sweltering 42°C (108°F). This month typically experiences dry conditions, with no precipitation days reported and a low humidity level of just 36%. In contrast to the cooler, more variable weather of other months, August offers a consistent warmth that makes it an ideal time for outdoor activities and exploring the region’s renowned vineyards. Dive deeper into the specifics of Napa's climate and discover what makes each month unique by visiting Napa Climate.