This report describes the historical weather record at the Boeing Field/King County International Airport (Seattle, Washington, United States) during 1955. This station has records back to January 1948.
Seattle, Washington has a mediterranean climate with dry warm summers and mild winters. The area within 25 mi of this station is covered by forests (61%), built-up areas (17%), oceans and seas (17%), and croplands (3%)
Daylight saving time (DST) was observed at Seattle, Washington during 1955. There were two time changes during 1955:
1955 was not a leap year, so it has 365 days and no February 29th. The first leap year before 1955 was 1952 and the first after was 1956.
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 1955 they occurred on:
|Spring Equinox||Monday, 21 March 1955.|
|Summer Solstice||Wednesday, 22 June 1955.|
|Fall Equinox||Friday, 23 September 1955.|
|Winter Solstice||Thursday, 22 December 1955.|
The hottest day of 1955 was June 9, with a high temperature of 98°F. For reference, on that day the average high temperature is 69°F and the high temperature exceeds 79°F only one day in ten. The hottest month of 1955 was August with an average daily high temperature of 72°F.
Relative to the average, the hottest day was June 9. The high temperature that day was 98°F, compared to the average of 69°F, a difference of 29°F. In relative terms the warmest month was January, with an average high temperature of 46°F, compared to an typical value of 47°F.
The longest warm spell was from June 6 to June 12, constituting 7 consecutive days with warmer than average high temperatures. The month of October had the largest fraction of warmer than average days with 39% days with higher than average high temperatures.
The coldest day of 1955 was November 15, with a low temperature of 9°F. For reference, on that day the average low temperature is 41°F and the low temperature drops below 33°F only one day in ten. The coldest month of 1955 was March with an average daily low temperature of 35°F.
Relative to the average, the coldest day was November 15. The low temperature that day was 9°F, compared to the average of 41°F, a difference of 32°F. In relative terms the coldest month was March, with an average low temperature of 35°F, compared to an typical value of 41°F.
The longest cold spell was from June 11 to August 30, constituting 81 consecutive days with cooler than average low temperatures. The month of July had the largest fraction of cooler than average days with 100% days with lower than average low temperatures.
The clearest month of 1955 was August, with 52% of days being more clear than cloudy. The longest spell of clear weather was from September 1 to September 6, constituting 6 consecutive days that were clearer than they were cloudy.
The cloudiest month of 1955 was January, with 94% of days being more cloudy than clear. The longest spell of cloudy weather was from June 12 to July 12, constituting 31 consecutive days that were cloudier than they were clear.
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.
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 1955 with the most precipitation observations was November 26. There were 23 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 November, with 226 hourly present weather reports involving some form of precipitation.
As determined by the present weather reports, the longest dry spell was from August 31 to September 13, constituting 14 consecutive days with no observed precipitation. The month with the largest fraction of days without observed precipitation was August, with 84% of days reporting no observed precipitation at all.
The month with the largest fraction of days with at least some observed precipitation was November, with 80% of days reporting some observed precipitation.
In this section we consider only those weather reports that indicate liquid precipitation. For the purposes of this analysis, we include thunderstorms even though some thunderstorms are not accompanied by liquid precipitation.
The month of 1955 with the largest number of those reports was November, with a total of 208 reports. The day with the largest number of those reports was November 26, with a total of 23 reports.
This station reports both when snow is observed to be falling and the measured depth of the snow on the ground. Both are subject to erroneous reports, but the latter is significantly less reliable. Please bear this in mind when reading this section.
In this section we consider hourly weather reports that contain an observation of falling snow. These reports do not necessarily correspond to accumulation.
The first reported snow fall in 1955 was on November 11; the last was on March 25. The month of 1955 with the largest number of those reports was March, with a total of 41 reports. The day with the largest number of those reports was February 26, with a total of 11 reports.
Snow depth on the ground is an optional and inconsistently reported part of standard weather reports. It is rarely reported more often than every six hours, it is often skipped, it is often reported erroneously, and a snow depth of zero is normally not distinguished from a missing report. These issues (particularly the last one) make it hard to collect statistics on snow depth with any confidence. To overcome this issue, we base our statistics on only those reports with present non-zero measurements of snow depth. Reports that fail to mention snow that is present, and reports that do not report snow depth because there is no snow on the ground are excluded because they cannot be distinguished from one another.
The first reported accumulation in 1955 was on November 12. The last day of the snow season with snow reported on the ground was March 4. The day with the deepest snow depth was November 18, with an average snow depth of 3.9" over the course of the day. The longest stretch of time during which there was always snow on the ground was from November 12 to November 15 (4 consecutive days).
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 1955 was May with an average daily low humidity of 45%, and the most humid month was January with an average daily low humidity of 68%.
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.
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 1955, January had 31 dry days, no comfortable days, and no humid days; April had 30 dry days, no comfortable days, and no humid days; July had 3 dry days, 28 comfortable days, and no humid days; and October had 14 dry days, 17 comfortable days, and no humid days.
The highest sustained wind speed was 37 mph, occurring on March 21; the highest daily mean wind speed was 21 mph (February 28);
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 6 mph.
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 1955 with the lowest average visibility was January 28, with an average visibility of 1.2 mi. The month with the lowest average visibility was January, with an average visibility of 7.7 mi. With an average visibility of 13.2 mi, the month of May had the highest average visibility.
This station did not reliably report the cloud ceiling during 1955.