Historical Weather For 1976 in San Jose, California, USA

Location

This report describes the historical weather record at the San Jose International Airport (San Jose, California, United States) during 1976. This station has records back to January 1968.

San Jose, California has a mediterranean climate with dry warm summers and mild winters. The area within 25 mi of this station is covered by grasslands (44%), forests (30%), built-up areas (14%), shrublands (8%), and oceans and seas (3%)

Calendar

Daylight saving time (DST) was observed at San Jose, California during 1976. There were two time changes during 1976:

  • DST started on Sunday April 25, 1976 at 3:00 am, from PST (GMT-8) to PDT (GMT-7).
  • DST ended on Sunday October 31, 1976 at 1:00 am, from PDT (GMT-7) to PST (GMT-8).

1976 was a leap year and thus has 366 days rather than the normal 365. Leap years occur every fourth year and the extra day is always February 29th. In 1976 February 29th falls on a Sunday.

The summer and winter solstices and the spring and fall equinoxes mark the passing of the seasons. They fall on nearly the same day each year, with differences of a day or two depending on the year. In 1976 they occurred on:

Spring Equinox Saturday, 20 March 1976.
Summer Solstice Monday, 21 June 1976.
Fall Equinox Wednesday, 22 September 1976.
Winter Solstice Tuesday, 21 December 1976.

Temperature

The hottest day of 1976 was June 27, with a high temperature of 103°F. For reference, on that day the average high temperature is 80°F and the high temperature exceeds 90°F only one day in ten. The hottest month of 1976 was June with an average daily high temperature of 81°F.

Relative to the average, the hottest day was May 12. The high temperature that day was 100°F, compared to the average of 74°F, a difference of 26°F. In relative terms the warmest month was December, with an average high temperature of 63°F, compared to an typical value of 60°F.

The longest warm spell was from January 14 to February 3, constituting 21 consecutive days with warmer than average high temperatures. The month of December had the largest fraction of warmer than average days with 87% days with higher than average high temperatures.

Temperature

The daily low (blue) and high (red) temperature during 1976 with the area between them shaded gray and superimposed over the corresponding averages (thick lines), and with percentile bands (inner band from 25th to 75th percentile, outer band from 10th to 90th percentile). The bar at the top of the graph is red where both the daily high and low are above average, blue where they are both below average, and white otherwise.

The coldest day of 1976 was January 2, with a low temperature of 30°F. For reference, on that day the average low temperature is 43°F and the low temperature drops below 35°F only one day in ten. The coldest month of 1976 was January with an average daily low temperature of 38°F.

Relative to the average, the coldest day was February 6. The low temperature that day was 30°F, compared to the average of 45°F, a difference of 15°F. In relative terms the coldest month was January, with an average low temperature of 38°F, compared to an typical value of 44°F.

The longest cold spell was from March 23 to April 6, constituting 15 consecutive days with cooler than average low temperatures. The month of January had the largest fraction of cooler than average days with 94% days with lower than average low temperatures.

Hourly Temperature Bands

The full year of hourly temperature reports with the days of the year on the horizontal and the hours of the day on the vertical. The hourly temperature measurement is color coded into meaningful temperature bands: frigid is purple (below 15°F), freezing is blue (15°F to 32°F), cold is dark green (32°F to 50°F), cool is light green (50°F to 65°F), comfortable is yellow (65°F to 75°F), warm is light red (75°F to 85°F), hot is medium red (85°F to 100°F), sweltering is dark red (above 100°F), and missing data is pink.

Clouds

The clearest month of 1976 was July, with 65% of days being more clear than cloudy. The longest spell of clear weather was from August 26 to September 4, constituting 10 consecutive days that were clearer than they were cloudy.

Cloud Coverage

The fraction of time spent in each of the five sky cover categories over the course of 1976 on a daily basis. From top (most blue) to bottom (most gray), the categories are clear, mostly clear, partly cloudy, mostly cloudy, and overcast. Pink indicates missing data. Outside of the United States clear skies are often reported ambiguously, leading them to be lumped in with the missing data. The bar at the top of the graph is gray if the sky was cloudy or mostly cloudy for more than half the day, blue if it is clear or mostly clear for more than half the day, and blue-gray otherwise.

The cloudiest month of 1976 was February, with 66% of days being more cloudy than clear. The longest spell of cloudy weather was from November 16 to November 26, constituting 11 consecutive days that were cloudier than they were clear.

Hourly Cloud Coverage

The full year of hourly cloud coverage reports with the days of the year on the horizontal and the hours of the day on the vertical. The sky cover is color coded: from most blue to most gray, the categories are clear, mostly clear, partly cloudy, mostly cloudy, and overcast. Pink indicates missing data. Outside of the United States clear skies are often reported ambiguously, leading them to be lumped in with the missing data.

Precipitation

This station provides hourly reports of significant weather events at and around the station, but does not report the quantity of precipitation at the station itself. This is common for weather stations located outside of the United States, and for a small subset of stations in the United States that are located at lesser used and smaller airports.

Present Weather Reports

This station reports when significant weather events (including precipitation) are visually observed at or near the station. Such events do not always correspond to measured quantities of liquid equivalent precipitation, such as when the event is near by not at the station, or in the case of solid precipitation that does not melt in the collection basin.

The day in 1976 with the most precipitation observations was February 8. There were 18 hourly weather reports that day (out of a maximum of 24) in which some form of precipitation was observated at or near the station. The month with the most precipitation observations was February, with 54 hourly present weather reports involving some form of precipitation.

Precipitation Reports

The daily number of hourly observed precipitation reports during 1976, color coded according to precipitation type, and stacked in order of severity. From the bottom up, the categories are thunderstorms (orange); heavy, moderate, and light snow (dark to light blue); heavy, moderate, and light rain (dark to light green); and drizzle (lightest green). Not all categories are necessarily present in this particular graph. The faint shaded areas indicate climate normals. The bar at the top of the graph is green if any precipitation was observed that day and white otherwise.

As determined by the present weather reports, the longest dry spell was from April 16 to June 10, constituting 56 consecutive days with no observed precipitation. The month May was completely without observed precipitation.

The month with the largest fraction of days with at least some observed precipitation was February, with 41% of days reporting some observed precipitation.

Hourly Weather Reports

The full year of hourly present weather reports with the days of the year on the horizontal and the hours of the day on the vertical. The color-coded categories are thunderstorms (orange); heavy, moderate, and light snow (dark to light blue); heavy, moderate, and light rain (dark to light green); drizzle (lightest green); freezing rain and sleet (light and dark cyan); snow grains (lightest blue); hail (red); fog (gray); and haze (brownish gray).

Snow

Either snow is exceptionally rare at this location or this station did not reliably report it during 1976.

Humidity

Humidity is an important factor in determining how weather conditions feel to a person experiencing them. Hot and humid days feel even hotter than hot and dry days because the high level of water content in humid air discourages the evaporation of sweat from a person's skin.

When reading the graph below, keep in mind that the hottest part of the day tends to be the least humid, so the daily low (brown) traces are more relevant for understanding daytime comfort than the daily high (blue) traces, which typically occur during the night. Applying that observation, the least humid month of 1976 was June with an average daily low humidity of 32%, and the most humid month was September with an average daily low humidity of 48%.

But it is important to keep in mind that humidity does not tell the whole picture and the dew point is often a better measure of how comfortable a person will find a given set of weather conditions. Please see the next section for continued discussion of this point.

Humidity

The daily low (brown) and high (blue) relative humidity during 1976 with the area between them shaded gray and superimposed over the corresponding averages (thick lines), and with percentile bands (inner band from 25th to 75th percentile, outer band from 10th to 90th percentile).

Dew Point

Dew point is the temperature below which water vapor will condense into liquid water. It is therefore also related to the rate of evaporation of liquid water. Since the evaporation of sweat is an important cooling mechanism for the human body, the dew point is an important measurement for understanding how dry, comfortable, or humid a given set of weather conditions will feel.

Generally speaking, dew points below 50°F will feel a bit dry to some people, but comfortable to people accustomed to dry conditions; dew points from 50°F to 68°F are fairly comfortable to most people, and dew points above 68°F are increasingly uncomfortable, becoming oppressive around 77°F.

To take some examples, and basing our categorization on the daily high dew point in 1976, January had 30 dry days, 1 comfortable day, and no humid days; April had 20 dry days, 10 comfortable days, and no humid days; July had no dry days, 30 comfortable days, and 1 humid day; and October had 1 dry day, 30 comfortable days, and no humid days.

Dew Point

The daily low (blue) and high (red) dew point during 1976 with the area between them shaded gray and superimposed over the corresponding averages (thick lines), and with percentile bands (inner band from 25th to 75th percentile, outer band from 10th to 90th percentile).

Wind

The highest sustained wind speed was 40 mph, occurring on February 7; the highest daily mean wind speed was 17 mph (April 16); and the highest wind gust speed was 40 mph (April 15).

The windiest month was April, with an average wind speed of 10 mph. The least windy month was January, with an average wind speed of 4 mph.

Wind Speed

The daily low and high wind speed (light gray area) and the maximum daily wind gust speed (tiny blue dashes).

Visibility

Visibility is the maximum distance at which a given reference object or light can be clearly discerned. In the United States, visibilities that are greater than or equal to 10 miles are typically reported as 10 miles.

The day of 1976 with the lowest average visibility was November 20, with an average visibility of 1.9 mi. The month with the lowest average visibility was December, with an average visibility of 7.0 mi. With an average visibility of 22.8 mi, the month of June had the highest average visibility.

Visibility

The daily average visibility, depicted as gray bars encroaching down from the top of the graph.

Cloud Ceiling

The cloud ceiling is the altitude of the lowest layer of clouds that are at categorized as broken (mostly cloudy) or overcast (cloudy). If no such cloud layer exists then the ceiling is unlimited and no value is reported.

The day of 1976 with the lowest average cloud ceiling was January 8, with an average cloud ceiling of 49'. The month with the lowest average cloud ceiling was December, with an average cloud ceiling of 3594'. The month of June has the highest average cloud ceiling, with an average cloud ceiling of 11398'.

Cloud Ceiling

The daily average cloud ceiling, depicted as gray bars encroaching down from the top of the graph. Missing data or days with insufficient clouds to define a cloud ceiling are shown as white columns.