July Weather in Napa, United States

Last updated: February 24, 2025

July in Napa, United States boasts warm and sunny weather, with maximum temperatures reaching a sweltering 40°C (104°F) and an inviting average of 21°C (70°F). The month is characterized by clear skies and delightful conditions, featuring zero precipitation, ensuring that visitors can enjoy outdoor activities without the threat of rain. Humidity remains comfortably low at 44%, contributing to the pleasure of soaking up the summer sun in this beautiful region. With such ideal conditions, Napa is the perfect destination for wine enthusiasts and adventurers alike.

July Temperature in Napa

In Napa, United States, July marks the height of summer, characterized by warm and inviting temperatures. With a minimum of 11°C (53°F) and a maximum of 40°C (104°F), the climate invites both locals and tourists to enjoy outdoor activities amidst the stunning vineyards. The average temperature remains steady at 21°C (70°F), making it an ideal time for wine tastings and leisurely strolls in the sun. As July follows the peak warmth in June, which can soar to 41°C (106°F), it signifies a slight ease in heat, yet still maintains a robust warmth, contributing to the area's vibrant, sunny ambiance. Overall, July showcases Napa's quintessential summer essence, fostering a lively atmosphere perfect for summer exploration and enjoyment.

July Weather in Napa: Daily Temperature Highs, Lows, and Averages

The chart illustrates July temperature patterns in Napa, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends.
JanFebMarAprMayJunJulAugSepOctNovDec505254596470707070655550
Data source: Temperature data for Napa generated using information from the Copernicus Climate Change Service.
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The average of daily temperatures (24 hours) calculated across all days in the month.

July Precipitation in Napa

In Napa, July marks the peak of summer, characterized by an impressive lack of precipitation, with the month receiving a total of 0 mm of rain across its 30 days. This trend follows a general downward trajectory in precipitation from the wetter months earlier in the year—from 119 mm in January to a mere 2 mm in June. The dry spell continues into August, where rainfall also hovers at 0 mm. Interestingly, this seasonal dryness creates a stark contrast to the previous winter months, illustrating Napa's seasonal climate variations. As summer unfolds, the absence of rain in July allows the sun to dominate, fostering ideal conditions for vineyards, yet also hinting at the arid challenges that may arise later in the year.

July Precipitation Trends in Napa

The chart displays monthly precipitation patterns in Napa, with values for each month alongside July's data, which is highlighted for easy comparison. It shows the amount of precipitation, providing insights into how July's conditions compare to those of other months.
JanFebMarAprMayJunJulAugSepOctNovDec1201138133192001294391
Data source: Precipitation data for July generated using information from the Copernicus Climate Change Service.
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July Humidity in Napa

In July, Napa experiences a notable shift in humidity, with levels dropping to just 44%, a significant decrease from the higher readings earlier in the year. This month marks a transition toward the driest period, as humidity consistently declines from March’s 83%. Following July, August continues this trend, reaching its lowest point at 36%, before a gradual increase begins in the fall. Overall, the data reflects a clear seasonal pattern where humidity peaks in the winter and early spring months, illustrating Napa's transformation into a warmer, drier climate as summer advances.

July Average Humidity in Napa

This chart illustrates the average monthly humidity levels in Napa, with July's data highlighted for easy comparison. It shows the fluctuation in humidity throughout the year, allowing you to see how July's humidity levels compare to other months.
JanFebMarAprMayJunJulAugSepOctNovDec84%84%83%81%74%64%44%37%44%65%84%83%
Data source: Humidity data for July generated using information from the Copernicus Climate Change Service.

July UV Index in Napa

In Napa, United States, the UV Index reaches its peak during the summer months, with July hitting an extreme level of 11. This trend follows a steady increase from moderate readings in January (UV Index 3) to very high levels in May and June, culminating in the intense sun exposure of July. The burn time significantly decreases as the index rises, with only 10 minutes of sun exposure recommended at its peak in July. Following the scorching summer, August sees a slight decline to a UV Index of 10, indicating that while the sun's intensity decreases, caution is still necessary. For a comprehensive understanding of UV trends throughout the year, visit Napa UV Index.

Maximum UV Index Levels in Napa for July

The chart shows the monthly maximum UV Index (UVI) for Napa in July, representing the highest UV radiation level. The UVI measures the intensity of ultraviolet radiation from the sun, indicating the potential risk of sunburn and UV-related health issues.
JanFebMarAprMayJunJulAugSepOctNovDec3579101111109643
Data source: Napa July UVI data generated using information from the Copernicus Climate Change Service.

UV Risk Categories

  •  Extreme (11+): Avoid the sun, stay in shade.
  •  Very High (8-10): Limit sun exposure.
  •  High (6-7): Use SPF 30+ and protective clothing.
  •  Moderate (3-5): Midday shade recommended.
  •  Low (0-2): No protection needed.

July Sunshine in Napa

As July graces Napa, it shines as the sunniest month of the year, boasting an impressive 394 hours of radiant sunshine. This peak in solar abundance follows a steady climb from the year's start, where January begins with only 141 hours of daylight. The gradual increase throughout the spring months highlights Napa's transition into summer, with hours of sunshine soaring from 296 in April to an impressive 384 in June. Following July, a slight decline in sunshine hours occurs in August, yet the overall warmth of the season remains, with 356 hours still illuminating the vineyards. This delightful pattern showcases Napa's inviting climate, making it a perfect destination for summer escapes and sunlit adventures.

Monthly Sunshine Duration in Napa: July Highlighted

The July sunshine duration represents the total number of hours Napa experiences direct sunlight during the month of July, excluding cloudy or obstructed periods. This chart compares the sunshine duration of July with the other months of the year.
JanFebMarAprMayJunJulAugSepOctNovDec141h210h257h296h357h384h394h356h314h280h220h185h
Data source: Napa July Sunshine duration data generated using information from the Copernicus Climate Change Service.

Chance of Sun in Napa During July

In July, Napa enjoys a promising likelihood of sunny weather, with a 73% chance of basking in the sunshine. This marks a slight dip from the previous months of May and June, both boasting an impressive 82% probability of clear skies. However, compared to the earlier months of the year, July remains a favorite for sun-seekers, particularly when juxtaposed with the 38% chance of sunshine in January. As summer peaks, travelers can expect to revel in the warmth, while still enjoying the beautiful unpredictability characteristic of Napa’s climate, where pleasant days transition smoothly into mellow evenings.

Percentage of Sunny Days in July in Napa

The chart illustrates the percentage of sunny days in Napa throughout the year, with July highlighted. It highlights the variation in sunshine across each month and provides an overview of the typical frequency of sunny days, offering insights into how often Napa experiences clear skies throughout the year.
JanFebMarAprMayJunJulAugSepOctNovDec38%58%63%70%82%82%73%79%76%53%45%31%
Data source: Napa July chance of sun data, generated using information from the Copernicus Climate Change Service.

Daylight Hours in Napa in July

In Napa, United States, July welcomes the peak of summer with 14 hours of daylight, reflecting a vibrant trend that starts in late spring. The daylight gradually increases from January's 9 hours to a lush 14 hours by both June and July, offering longer days perfect for exploring the picturesque vineyards and enjoying outdoor adventures. As the year progresses into August, daylight begins to taper off slightly to 13 hours, hinting at the approach of fall. This gradual transition showcases Napa’s beautifully rhythmic seasonal changes, where each month offers a unique opportunity to savor the sun-drenched landscapes and bountiful harvests.

Average Daylight Hours in Napa for July

The chart illustrates the variation in daylight duration in Napa throughout the year, with July highlighted. It shows the monthly changes in daylight hours, calculated by summing the hours between sunrise and sunset.
JanFebMarAprMayJunJulAugSepOctNovDec9h 50m10h 46m11h 59m13h 13m14h 15m14h 46m14h 29m13h 33m12h 22m11h 8m10h 4m9h 32m
Data source: Napa daylight hours, calculated by summing the hours between sunrise and sunset for each day.

July Winds in Napa

In July, the breezes in Napa, United States, gently sway with an average wind speed of 3.0 m/s (7 mph), maintaining the momentum built over the previous months. This is a slight decrease from June's peak of 3.3 m/s, yet still represents a vibrant summer atmosphere. As the year progresses, we see a trend of increasing wind speeds from the calm of January at 2.0 m/s (5 mph) to the energetic gusts of July. Following this mid-summer breeze, there’s an anticipated decline in wind speeds through August, hinting at the transition toward the more tranquil months of fall. Overall, July's winds play a refreshing role in Napa's warm climate, providing a delightful contrast to the sun-drenched vineyards.

Average July Wind Speed in Napa

The chart displays monthly wind speed patterns in Napa, with values for each month shown alongside July's data, which is highlighted for easy comparison. It illustrates the average wind speed, offering insights into how July's wind conditions compare to the rest of the year.
JanFebMarAprMayJunJulAugSepOctNovDec2.02.42.52.73.13.33.0 m/s2.72.42.31.62.0
Data source: Napa July wind data, generated using information from the Copernicus Climate Change Service.

How July Weather in Napa Compares to Other Months

The weather in Napa changes throughout the year, offering a unique experience in each season. Below is a month-by-month comparison of July'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.

When comparing the weather of July and January, the differences are striking. July boasts warm temperatures, with averages around 21°C (70°F) and a maximum reaching up to 40°C (104°F), while January experiences much cooler conditions, averaging only 10°C (50°F) and peaking at 25°C (77°F). Additionally, July is characterized by dry weather, with no recorded precipitation or humid days, while January shows a wetter climate with 119 mm (4.7 in) of rainfall over eight rainy days and a significantly higher humidity level of 84%. For further details about January's weather, you can visit Napa weather in January.

When comparing the weather in July and February, the contrast is striking. July boasts high temperatures that can soar up to 40°C (104°F), with a comfortable average of 21°C (70°F) and no recorded precipitation. In stark contrast, February has a much cooler climate, with temperatures ranging from a frigid minimum of -1°C (30°F) to a maximum of 27°C (80°F), and it experiences significant rainfall of 113 mm (4.5 in) over approximately seven days. Additionally, February’s humidity level is considerably higher at 84%, compared to July’s 44%. For more detailed information on February’s weather, you can visit Napa weather in February.

July and March exhibit stark contrasts in weather conditions. July boasts warmer temperatures, with an average of 21°C (70°F) and maximums soaring up to 40°C (104°F), while March remains cooler, averaging 12°C (55°F) with maximums reaching only 30°C (87°F). Additionally, July experiences dry conditions with no recorded precipitation and a low humidity level of 44%, making it a much more arid month. In contrast, March is characterized by significant rainfall, receiving 81 mm (3.2 in) over about 9 days and higher humidity at 83%. For those interested in exploring the specifics of March weather in Napa, more information can be found here: Napa weather in March.

In comparing the weather of July and April, it is clear that July is characterized by significantly warmer temperatures, with a minimum of 11°C (53°F) and an average high reaching up to 40°C (104°F). In contrast, April experiences cooler temperatures, with a minimum of 3°C (38°F) and an average high of 33°C (92°F). While July boasts completely dry conditions with no recorded precipitation and only 44% humidity, April sees a notable amount of rainfall, totaling 33 mm (1.3 inches) across five days and a much higher humidity level of 81%. For more details on what to expect in April, you can check out Napa weather in April.

In comparing the weather of July and May, July tends to be significantly warmer and drier. July boasts a minimum temperature of 11°C (53°F) and an average of 21°C (70°F), reaching a maximum of 40°C (104°F) without any recorded precipitation. In contrast, May has lower temperatures, with a minimum of 5°C (41°F) and an average of 18°C (64°F), peaking at 37°C (99°F) and experiencing 19 mm (0.8 in) of rain over two days. Additionally, humidity levels in May are noticeably higher at 74%, compared to July's 44%. For more details on the weather patterns in May, you can check Napa weather in May.

In comparing the weather of July and June, both months boast similar average temperatures of 21°C (70°F), but July tends to have slightly higher minimum and maximum temperatures, with lows of 11°C (53°F) and highs reaching up to 40°C (104°F). In contrast, June features a minimum temperature of 10°C (51°F) and a maximum of 41°C (106°F). Additionally, July is quite dry, recording no precipitation, while June experiences minimal rainfall of 2 mm (0.1 in) despite having the higher humidity level of 64%. This makes July feel considerably drier with only 44% humidity. For a more detailed look at June weather specifics, you can visit Napa weather in June.

July and August both feature warm temperatures, with July averaging 21°C (70°F) and reaching a maximum of 40°C (104°F), while August has a similar average of 21°C (71°F) and a slightly higher maximum of 42°C (108°F). Both months enjoy dry conditions with no recorded precipitation or rainy days. However, humidity levels do vary slightly, with July at 44% and August experiencing a lower level at 36%. For more detailed information, you can check out Napa weather in August.

In July, the weather features a minimum temperature of 11°C (53°F), with an average of 21°C (70°F) and a maximum reaching up to 40°C (104°F), making it quite warm. Notably, July experiences no rainfall, resulting in dry conditions with humidity at a steady 44%. In contrast, September sees slightly cooler minimum temperatures at 8°C (46°F) while maintaining an average of 21°C (70°F) and a maximum temperature of 44°C (111°F). While precipitation remains minimal at just 1 mm, there are still no rainy days, and the humidity remains consistent at 44%. For more detailed information, check out this Napa weather in September.

July and October present distinctly different weather patterns. In July, temperatures soar, with highs reaching up to 40°C (104°F) and little to no rainfall, resulting in a dry climate with only 44% humidity. In contrast, October experiences cooler temperatures, with a minimum of 4°C (40°F) and an average of 18°C (65°F). There's a significant increase in precipitation during this month, with 29 mm (1.1 in) over two days and humidity levels rising to 65%. For more information on the specific weather conditions in October, you can check Napa weather in October.

In comparing July and November weather, July is characterized by much warmer temperatures, with minimums around 11°C (53°F) and maximums reaching up to 40°C (104°F), while November sees a cooler range, with minimums dropping to 0°C (32°F) and maximums peaking at 30°C (86°F). While July boasts a dry climate with no recorded precipitation, November experiences a significant increase in rainfall, averaging 43 mm (1.7 in) over about 5 days. Furthermore, humidity levels are considerably higher in November at 84%, compared to July's 44%. For more details on November conditions, you can check Napa weather in November.

July and December present stark contrasts in weather. In July, temperatures can soar, with a minimum of 11°C (53°F) and a maximum reaching up to 40°C (104°F), while average temperatures hover around a comfortable 21°C (70°F). This month experiences virtually no precipitation, with humidity at a moderate 44%. In contrast, December is much cooler, with temperatures ranging from a minimum of 0°C (32°F) to a maximum of 24°C (75°F) and an average of 10°C (50°F). It brings significant rainfall, accumulating 91 mm (3.6 in) over about 9 days, and is characterized by high humidity at 83%. For more details on December's weather in Napa, check out Napa weather in December.

Compare Napa's Climate with Cities Worldwide

Conclusion: What to Expect From July Weather in Napa

July in Napa presents a breathtaking contrast to other months, with the sun gracing the region with warm temperatures, averaging a delightful 21°C (70°F), and soaring highs of 40°C (104°F). This month is characterized by an absence of precipitation, making it the driest part of the year, which results in crisp and clear skies perfect for outdoor activities and wine tasting. With humidity at a comfortable 44%, visitors can enjoy the warmth without feeling overwhelmed. This ideal summer weather makes Napa a sought-after destination during July, showcasing the region's beauty and inviting guests to relish in its unique climate. For more insights on seasonal shifts, explore Napa Climate.