Months

January is the first month of the year in the Julian and Gregorian calendars. Its length is 31 days. The first day of the month is known as New Year's Day. It is, on average, the coldest month of the year within most of the Northern Hemisphere (where it is the second month of winter) and the warmest month of the year within most of the Southern Hemisphere (where it is the second month of summer). In the Southern hemisphere, January is the seasonal equivalent of July in the Northern hemisphere and vice versa.

April is the fourth month of the year in the Gregorian and Julian calendars. Its length is 30 days.

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thumb|Red maple (Acer rubrum) leaf in October (Northern hemisphere). thumb |In recent decades, the number of warm temperature records in October has outpaced cold temperature records over a growing portion of Earth's surface. thumb |Chart shows changes in global average temperature annually in October of each year

March is the current month, and the third month of the year in both the Julian and Gregorian calendars. Its length is 31 days. In the Northern Hemisphere, the meteorological beginning of spring occurs on the first day of March. The March equinox on the 20 or 21 marks the astronomical beginning of spring in the Northern Hemisphere and the beginning of autumn in the Southern Hemisphere, where September is the seasonal equivalent of the Northern Hemisphere's March.

May is the fifth month of the year in the Julian and Gregorian calendars. Its length is 31 days.

thumb|Depiction of harvesting in the August calendar page of the Queen Mary Psalter (fol. 78v), ca. 1310 thumb |In recent decades, the number of warm temperature records in August has outpaced cold temperature records over a growing portion of Earth's surface. thumb |Chart shows changes in global average temperature annually in August of each year

November is the 11th and penultimate month of the year in the Julian and Gregorian calendars. Its length is 30 days. November was the ninth month of the calendar of Romulus . November retained its name (from the Latin novem meaning "nine") when January and February were added to the Roman calendar. November is a month of late spring in the Southern Hemisphere and late autumn in the Northern Hemisphere. Therefore, November in the Southern Hemisphere is the seasonal equivalent of May in the Northern Hemisphere and vice versa. In Ancient Rome, Ludi Plebeii was held from November 4–17, Epulum Jovi

February is the second month of the year in the Julian and Gregorian calendars. The month has 28 days in common years and 29 in leap years, with the 29th day being called the leap day. February is the third and last month of meteorological winter in the Northern Hemisphere. In the Southern Hemisphere, February is the third and last month of meteorological summer, being the seasonal equivalent of August in the Northern Hemisphere. February is preceded by the first month of the year, January, and is succeeded by the third month of the year, March.

December is the 12th and final month of the year in the Julian and Gregorian calendars. Its length is 31 days. right|thumb|December, from the Très Riches Heures du duc de Berry thumb |In recent decades, the number of warm temperature records in December has outpaced cold temperature records over a growing portion of Earth's surface. thumb |Chart shows changes in global average temperature annually in December of each year

July is the seventh month of the year in the Julian and Gregorian calendars. Its length is 31 days. It was named by the Roman Senate in honour of Roman general and statesman Julius Caesar in 44 B.C., being the month of his birth. Before then it was called Quintilis, being the fifth month of the calendar that started with March.

September is the ninth month of the year in the Julian and Gregorian calendars. Its length is 30 days. right|thumb|September, from the Très Riches Heures du Duc de Berry thumb |In recent decades, the number of warm temperature records in September has outpaced cold temperature records over a growing portion of Earth's surface. thumb |Chart shows changes in global average temperature annually in September of each year

A month is a unit of time, used with calendars, that is approximately as long as a natural phase cycle of the Moon; the words month and Moon are cognates. The traditional concept of months arose with the cycle of Moon phases; such lunar months ("lunations") are synodic months and last approximately 29.53 days, making for roughly 12.37 such months in one Earth year. From excavated tally sticks, researchers have deduced that people counted days in relation to the Moon's phases as early as the Paleolithic age. Synodic months, based on the Moon's orbital period with respect to the Earth–Sun line,

units of time based on the Moon

thumb|300px|Detail of Menologium, showing saints and martyrs of December, January and February, painted by John Tokhabi, 11th century [[tetraptych, kept at the Saint Catherine's Monastery.]] A menologium (, pl. menologia), also known by other names, is any collection of information arranged according to the days of a month, usually a set of such collections for all the months of the year. In particular, it is used for ancient Roman farmers' almanacs (); for the untitled Old English poem on the Julian calendar that appears in a manuscript of the Anglo-Saxon Chronicle; for the liturgical books (

renaming of months and days of week in Turkmenistan

calendar

Mercedonius (Latin for "Work Month"), also known as Mercedinus, Interkalaris or Intercalaris (), was the intercalary month of the Roman calendar. The resulting leap year was either 377 or 378 days long. It theoretically occurred every two (or occasionally three) years, but was sometimes avoided or employed by the Roman pontiffs for political reasons regardless of the state of the solar year. Mercedonius was eliminated by Julius Caesar when he introduced the Julian calendar in 45 BC.

four months of the Islamic calendar

Undecimber or Undecember is a name for a thirteenth month in a calendar that normally has twelve months.

names of Macedonian months

Arabic names of calendar months

Navasard is the first month of the Armenian calendar. Navasard has 30 days, starting on 11 August and ending on 9 September. In ancient Armenia, the first day of Navasard was a holiday. In Armenian mythology, the Navasardian god was considered protector of the crops and the feeder of the hungry. His statue is currently standing in Bagavan, which today is considered a Pagan sanctuary.

Þorri () is the Icelandic name of the personification of frost or winter in Norse mythology, and also the name of the fourth winter month (mid January to mid February) in the Icelandic calendar.

month in the babylonian calendar