The climate in Mountain View is warm, humid, windy, and partly cloudy. Over the course of the year, the temperature typically varies from 59°F to 80°F and is rarely below 55°F or above 83°F.
Click on each chart for more information.
Based on the tourism score, the best time of year to visit Mountain View for warm-weather activities is from mid May to early October.
The temperature in Mountain View varies so little throughout the year that it is not entirely meaningful to discuss hot and cold seasons.
Average High and Low Temperature
The daily average high (red line) and low (blue line) temperature, with 25th to 75th and 10th to 90th percentile bands. The thin dotted lines are the corresponding average perceived temperatures.
The figure below shows you a compact characterization of the entire year of hourly average temperatures. The horizontal axis is the day of the year, the vertical axis is the hour of the day, and the color is the average temperature for that hour and day.
Average Hourly Temperature
The average hourly temperature, color coded into bands: frigid < 15°F < freezing < 32°F < very cold < 45°F < cold < 55°F < cool < 65°F < comfortable < 75°F < warm < 85°F < hot < 95°F < sweltering. The shaded overlays indicate night and civil twilight.
In Mountain View, the average percentage of the sky covered by clouds experiences significant seasonal variation over the course of the year.
The clearer part of the year in Mountain View begins around May 17 and lasts for 4.1 months, ending around September 20. On August 8, the clearest day of the year, the sky is clear, mostly clear, or partly cloudy77% of the time, and overcast or mostly cloudy23% of the time.
The cloudier part of the year begins around September 20 and lasts for 7.9 months, ending around May 17. On October 28, the cloudiest day of the year, the sky is overcast or mostly cloudy48% of the time, and clear, mostly clear, or partly cloudy52% of the time.
Cloud Cover Categories
The percentage of time spent in each cloud cover band, categorized by the percentage of the sky covered by clouds: clear < 20% < mostly clear < 40% < partly cloudy < 60% < mostly cloudy < 80% < overcast.
A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. The chance of wet days in Mountain View varies throughout the year.
The wetter season lasts 10 months, from September 26 to July 29, with a greater than 29% chance of a given day being a wet day. The chance of a wet day peaks at 34% on April 7.
The drier season lasts 1.9 months, from July 29 to September 26. The smallest chance of a wet day is 24% on August 29.
Among wet days, we distinguish between those that experience rain alone, snow alone, or a mixture of the two. Based on this categorization, the most common form of precipitation throughout the year is rain alone, with a peak probability of 34% on April 7.
Daily Chance of Precipitation
The percentage of days in which various types of precipitation are observed, excluding trace quantities: rain alone, snow alone, and mixed (both rain and snow fell in the same day).
To show variation within the months and not just the monthly totals, we show the rainfall accumulated over a sliding 31-day period centered around each day of the year. Mountain View experiences extreme seasonal variation in monthly rainfall.
Rain falls throughout the year in Mountain View. The most rain falls during the 31 days centered around April 12, with an average total accumulation of 8.0 inches.
The least rain falls around June 6, with an average total accumulation of 2.4 inches.
Average Monthly Rainfall
The average rainfall (solid line) accumulated over the course of a sliding 31-day period centered on the day in question, with 25th to 75th and 10th to 90th percentile bands. The thin dotted line is the corresponding average liquid-equivalent snowfall.
The length of the day in Mountain View varies over the course of the year. In 2018, the shortest day is December 21, with 10 hours, 57 minutes of daylight; the longest day is June 21, with 13 hours, 19 minutes of daylight.
Hours of Daylight and Twilight
The number of hours during which the Sun is visible (black line). From bottom (most yellow) to top (most gray), the color bands indicate: full daylight, twilight (civil, nautical, and astronomical), and full night.
The earliest sunrise is at 5:41 AM on June 6, and the latest sunrise is 1 hour, 16 minutes later at 6:57 AM on January 18. The earliest sunset is at 5:40 PM on November 25, and the latest sunset is 1 hour, 23 minutes later at 7:03 PM on July 5.
Daylight saving time (DST) is not observed in Mountain View during 2018.
Sunrise & Sunset with Twilight
The solar day over the course of the year 2018. From bottom to top, the black lines are the previous solar midnight, sunrise, solar noon, sunset, and the next solar midnight. The day, twilights (civil, nautical, and astronomical), and night are indicated by the color bands from yellow to gray.
We base the humidity comfort level on the dew point, as it determines whether perspiration will evaporate from the skin, thereby cooling the body. Lower dew points feel drier and higher dew points feel more humid. Unlike temperature, which typically varies significantly between night and day, dew point tends to change more slowly, so while the temperature may drop at night, a muggy day is typically followed by a muggy night.
Mountain View experiences extreme seasonal variation in the perceived humidity.
The muggier period of the year lasts for 6.8 months, from May 15 to December 7, during which time the comfort level is muggy, oppressive, or miserable at least 22% of the time. The muggiest day of the year is August 13, with muggy conditions 67% of the time.
The least muggy day of the year is February 14, with muggy conditions 7% of the time.
Humidity Comfort Levels
The percentage of time spent at various humidity comfort levels, categorized by dew point: dry < 55°F < comfortable < 60°F < humid < 65°F < muggy < 70°F < oppressive < 75°F < miserable.
This section discusses the wide-area hourly average wind vector (speed and direction) at 10 meters above the ground. The wind experienced at any given location is highly dependent on local topography and other factors, and instantaneous wind speed and direction vary more widely than hourly averages.
The average hourly wind speed in Mountain View experiences mild seasonal variation over the course of the year.
The windier part of the year lasts for 2.0 months, from March 8 to May 7, with average wind speeds of more than 10.8 miles per hour. The windiest day of the year is April 7, with an average hourly wind speed of 11.8 miles per hour.
The calmer time of year lasts for 10 months, from May 7 to March 8. The calmest day of the year is January 12, with an average hourly wind speed of 9.7 miles per hour.
Average Wind Speed
The average of mean hourly wind speeds (dark gray line), with 25th to 75th and 10th to 90th percentile bands.
The predominant average hourly wind direction in Mountain View is from the east throughout the year.
The percentage of hours in which the mean wind direction is from each of the four cardinal wind directions (north, east, south, and west), excluding hours in which the mean wind speed is less than 1 mph. The lightly tinted areas at the boundaries are the percentage of hours spent in the implied intermediate directions (northeast, southeast, southwest, and northwest).
Mountain View is located near a large body of water (e.g., ocean, sea, or large lake). This section reports on the wide-area average surface temperature of that water.
The average water temperature experiences some seasonal variation over the course of the year.
The time of year with warmer water lasts for 3.2 months, from July 31 to November 6, with an average temperature above 79°F. The day of the year with the warmest water is September 11, with an average temperature of 80°F.
The time of year with cooler water lasts for 4.0 months, from January 7 to May 8, with an average temperature below 76°F. The day of the year with the coolest water is March 1, with an average temperature of 76°F.
Average Water Temperature
The daily average water temperature (purple line), with 25th to 75th and 10th to 90th percentile bands.
Best Time of Year to Visit
To characterize how pleasant the weather is in Mountain View throughout the year, we compute two travel scores.
The tourism score favors clear, rainless days with perceived temperatures between 65°F and 80°F. Based on this score, the best time of year to visit Mountain View for general outdoor tourist activities is from mid May to early October, with a peak score in the last week of July.
The tourism score (filled area), and its constituents: the temperature score (red line), the cloud cover score (blue line), and the precipitation score (green line).
The beach/pool score favors clear, rainless days with perceived temperatures between 75°F and 90°F. Based on this score, the best time of year to visit Mountain View for hot-weather activities is from mid July to early September, with a peak score in the last week of July.
The beach/pool score (filled area), and its constituents: the temperature score (red line), the cloud cover score (blue line), and the precipitation score (green line).
For each hour between 8:00 AM and 9:00 PM of each day in the analysis period (1980 to 2016), independent scores are computed for perceived temperature, cloud cover, and total precipitation. Those scores are combined into a single hourly composite score, which is then aggregated into days, averaged over all the years in the analysis period, and smoothed.
Our cloud cover score is 10 for fully clear skies, falling linearly to 9 for mostly clear skies, and to 1 for fully overcast skies.
Our precipitation score, which is based on the three-hour precipitation centered on the hour in question, is 10 for no precipitation, falling linearly to 9 for trace precipitation, and to 0 for 0.04 inches of precipitation or more.
Our tourism temperature score is 0 for perceived temperatures below 50°F, rising linearly to 9 for 65°F, to 10 for 75°F, falling linearly to 9 for 80°F, and to 1 for 90°F or hotter.
Our beach/pool temperature score is 0 for perceived temperatures below 65°F, rising linearly to 9 for 75°F, to 10 for 82°F, falling linearly to 9 for 90°F, and to 1 for 100°F or hotter.
Definitions of the growing season vary throughout the world, but for the purposes of this report, we define it as the longest continuous period of non-freezing temperatures (≥ 32°F) in the year (the calendar year in the Northern Hemisphere, or from July 1 until June 30 in the Southern Hemisphere).
Temperatures in Mountain View are sufficiently warm year round that it is not entirely meaningful to discuss the growing season in these terms. We nevertheless include the chart below as an illustration of the distribution of temperatures experienced throughout the year.
Time Spent in Various Temperature Bands and the Growing Season
The percentage of time spent in various temperature bands: frigid < 15°F < freezing < 32°F < very cold < 45°F < cold < 55°F < cool < 65°F < comfortable < 75°F < warm < 85°F < hot < 95°F < sweltering. The black line is the percentage chance that a given day is within the growing season.
Growing degree days are a measure of yearly heat accumulation used to predict plant and animal development, and defined as the integral of warmth above a base temperature, discarding any excess above a maximum temperature. In this report, we use a base of 50°F and a cap of 86°F.
Growing Degree Days
The average growing degree days accumulated over the course of the year, with 25th to 75th and 10th to 90th percentile bands.
This section discusses the total daily incident shortwave solar energy reaching the surface of the ground over a wide area, taking full account of seasonal variations in the length of the day, the elevation of the Sun above the horizon, and absorption by clouds and other atmospheric constituents. Shortwave radiation includes visible light and ultraviolet radiation.
The average daily incident shortwave solar energy experiences some seasonal variation over the course of the year.
The brighter period of the year lasts for 4.5 months, from April 22 to September 7, with an average daily incident shortwave energy per square meter above 6.8 kWh. The brightest day of the year is July 27, with an average of 7.4 kWh.
The darker period of the year lasts for 2.6 months, from November 6 to January 27, with an average daily incident shortwave energy per square meter below 5.0 kWh. The darkest day of the year is December 6, with an average of 4.4 kWh.
Average Daily Incident Shortwave Solar Energy
The average daily shortwave solar energy reaching the ground per square meter (orange line), with 25th to 75th and 10th to 90th percentile bands.
For the purposes of this report, the geographical coordinates of Mountain View are 19.556 deg latitude, -155.108 deg longitude, and 1,519 ft elevation.
The topography within 2 miles of Mountain View contains very significant variations in elevation, with a maximum elevation change of 850 feet and an average elevation above sea level of 1,496 feet. Within 10 miles contains very significant variations in elevation (4,232 feet). Within 50 miles also contains extreme variations in elevation (13,816 feet).
The area within 2 miles of Mountain View is covered by cropland (56%), trees (18%), and artificial surfaces (17%), within 10 miles by trees (67%) and shrubs (15%), and within 50 miles by water (59%) and shrubs (11%).
This report illustrates the typical weather in Mountain View, based on a statistical analysis of historical hourly weather reports and model reconstructions from January 1, 1980 to December 31, 2016.
Temperature and Dew Point
There are 2 weather stations near enough to contribute to our estimation of the temperature and dew point in Mountain View.
The estimated value at Mountain View is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Mountain View and a given station.
All other weather data, including cloud cover, precipitation, wind speed and direction, and solar flux, come from NASA's MERRA-2 Modern-Era Retrospective Analysis . This reanalysis combines a variety of wide-area measurements in a state-of-the-art global meteorological model to reconstruct the hourly history of weather throughout the world on a 50-kilometer grid.
The information on this site is provided as is, without any assurances as to its accuracy or suitability for any purpose. Weather data is prone to errors, outages, and other defects. We assume no responsibility for any decisions made on the basis of the content presented on this site.
We draw particular cautious attention to our reliance on the MERRA-2 model-based reconstructions for a number of important data series. While having the tremendous advantages of temporal and spatial completeness, these reconstructions: (1) are based on computer models that may have model-based errors, (2) are coarsely sampled on a 50 km grid and are therefore unable to reconstruct the local variations of many microclimates, and (3) have particular difficulty with the weather in some coastal areas, especially small islands.
We further caution that our travel scores are only as good as the data that underpin them, that weather conditions at any given location and time are unpredictable and variable, and that the definition of the scores reflects a particular set of preferences that may not agree with those of any particular reader.