DESCRIPTIONS OF CLIMATE GRAPHS:

Richmond Historical Annual Average Temperature:

Period of Record: 1881-Present

(City and Park Office 1881-1929, Airport 1930-Present)

This graph shows the annual average temperature for each year. Note that average temperature refers to the average of the high and low temperature. The long term average temperature shown in text in the bottom portion of the graph is based on this entire period of record and will differ slightly from the 1971-2000 normal.


Richmond Historical Annual Precipitation:

Period of Record: 1872-Present

(City and Park Office 1872-1937, Airport 1938-Present)

This graph shows the total precipitation (in inches) for each year. The long term average yearly precipitation shown in text in the bottom portion of the graph is based on this entire period of record and will differ slightly from the 1971-2000 normal.


Richmond Historical Snowfall:

Period of Record: 1897/98 Season-Present

(City and Park Office 1897/98-1936/37, Airport 1937/38-Present)

This graph shows the total snowfall (in inches) for each season. A season begins in the fall and ends in the spring of the following year. The long term average snowfall shown in text in the bottom portion of the graph is based on this entire period of record and will differ slightly from the 1971-2000 normal.


Richmond Historical Daily Temperatures:

Period of Record: 1897-Present

(City and Park Office 1897-1929, Airport 1930-Present)

For every date of the year, the thin brown line depicts the record high temperature, the red line shows the average high temperature, the blue line shows the average low temperature, and the thin dark line gives the record low temperature. This data is based on the entire period of record and will differ slightly from the normals. In addition, this data is strictly determined from the averages unlike the 1971-2000 normals which involve a smoothing function.


Richmond Historical Daily Precipitation:

 Period of Record: 1887-Present

(City and Park Office 1887-1937, Airport 1938-Present)

The data for this graph is based on a period of record from 1887 through the current year. The thin dark line depicts the actual percent chance of measurable precipitation (at least 0.01) for every day of the year and is plotted against the left axis. The thick dark line is a best fit curve of the data. The brown bars at the bottom are plotted against the right axis and show the number of times when a daily total of 2 inches or more of precipitation was recorded. For example, on September 5 th, there is a 28% chance of measurable precipitation (33 times out of the 119-year period saw measurable precipitation), and in 3 cases (out of 119 times) at least 2 inches of daily precipitation fell.


Richmond Historical 90-Degree Days:

Period of Record: 1897-Present

(City and Park Office 1897-1929, Airport 1930-Present)

The graph shows the 10 years with the greatest number of 90 degree (or warmer) days, the 10 years with the least amount of 90 degree days, and the average number of 90-degree days. Since records began in 1897, the year with the most is 1977 when 70 days reached 90 degrees or higher, the years with the least were 1971, 1927, and 1917 when only 14 days topped out at 90 or higher. The long term average (1897-present) is 40 such days, and will differ slightly from the 1971-2000 normal.


Richmond Precipitation by Month Breakdown:

Period of Record: 1971-2000 (Airport)

For each month of the year, this graph depicts the average precipitation (in inches) with green bars and is plotted against the left axis. In addition, the black line shows the number of days per month that receive measurable (0.01 or more) precipitation and is plotted against the right axis. The graph shows that February is the driest month of the year in terms of total precipitation (2.98 average). However on average, October records the fewest number of days with measurable precipitation (7.5 days).


Richmond Snowfall by Month Breakdown:

Period of Record: 1971-2000 (Airport)

For each month of the year, this graph depicts the average snowfall (in inches) with purple bars and is plotted against the left axis. In addition, the black line shows the number of days per month that receive measurable (0.1 or more) snowfall and is plotted against the right axis.  The graph shows that on average, February is the snowiest month of the year in terms of total snowfall with 4.9. Both January and February average just over 2 days per month with measurable snowfall.


Richmond Temperature Top 10 List:

Period of Record: 1881-Present

(City and Park Office 1881-1929, Airport 1930-Present)

This table shows the 10 warmest and coldest months, seasons, and years on record for average temperature.  Note that average temperature refers to the average of the high and  low temperatures for a given time frame. The values given in the yellow rows labeled AVG are the averages of the average temperatures based on the entire period of record and will differ slightly from the 1971-2000 normals.


Richmond Precipitation Top 10 List:

Period of Record: 1872-Present

(City and Park Office 1872-1937, Airport 1938-Present)

This table shows the 10 wettest and driest months, seasons, and years on record. The values given in the yellow rows labeled AVG depict the average precipitation based on the entire period of record and will differ slightly from the 1971-2000 normals.