So Monday will be the seventeenth.
St Valentine’s Day is on the fourteenth.
There is more information about ordinals in the Reference Section.
months, seasons, and dates
4.89 The twelve months of the year are proper nouns:
January
February
March
April
May
June
July
August
September
October
November
December
There are four seasons: spring, summer, autumn (usually fall in American English) and winter. Springtime, summertime, and wintertime are also used.
Some periods of the year have special names; for example, Christmas, Easter, and the New Year.
years, decades, and centuries
4.90 Years are referred to in English by numbers. When you are speaking, you refer to years before 2000 as nineteen sixty-seven (1967), or seventeen hundered (1700), for example.
…the eleventh of January, 1967.
A second conference was held in February 1988.
My mother died in 1945.
When you are speaking, you refer to years between 2000 and 2009 as two thousand (2000) or two thousand and eight (2008), for example.
Years after 2009 are said as either two thousand and ten (2010), two thousand and eleven (2011), etc. or as twenty ten (2010), twenty eleven (2011), etc.
To refer to periods longer than a year, decades (ten years) and centuries (a hundred years) are used. Decades start with a year ending in zero and finish with a year ending in nine: the 1960s (1960 to 1969), the 1820s (1820 to 1829). If the century is already known, it can be omitted: the 20s, the twenties, the Twenties.
To be more specific, for example in historical dates, AD is added before or after the numbers for years or centuries after Jesus is believed to have been born: 1650 AD, AD 1650, AD 1650-53, 1650-53 AD. Some writers who prefer to avoid referring to religion use CE, which stands for the Common Era: 1650 CE.
BC (which stands for Before Christ) is added after the numbers for years or centuries before Jesus is believed to have been born: 1500 BC, 15–1200 BC. An alternative abbreviation that does not refer to religion is BCE, which stands for Before the Common Era.
Centuries start with a year ending in two zeroes and finish with a year ending in two nines. Ordinals are used to refer to them. The first century was from 0 AD to 99 AD, the second century was 100–199 AD, and so on, so the period 1800–1899 AD was the nineteenth century and the current century is the twenty-first century (2000–2099 AD). Centuries can also be written using numbers: the 21st century.
at for specific times
4.91 If you want to say when something happens, you use at with clock times, periods of the year, and periods of the day except for morning, evening, afternoon, and daytime.
Our train went at 2.25.
I got up at eight o’clock.
The train should arrive at a quarter to one.
We go to church at Easter and Christmas.
I went down and fetched her back at the weekend.
On Tuesday evening, just at dusk, Brody had received an anonymous phone call.
He regarded it as his duty to come and read to me at bedtime.
At night we kept them shut up in a wire enclosure.
Let the fire burn out now. Who would see smoke at night-time anyway?
You can also use at with time and similar words such as moment and juncture and with units of clock time such as hour and minute.
General de Gaulle duly attended the military ceremony at the appointed time.
It was at this juncture that his luck temporarily deserted him.
If I could have done it at that minute I would have killed him.
There were no lights at this hour, and roads, bungalows, and gardens lay quiet.
at for relating events
4.92 You can also use at when you want to relate the time of one event to another event such as a party, journey, election, and so on.
I had first met Kruger at a party at the British Embassy.
She represented the Association at the annual meeting of the American Medical Association in Chicago.
It is to be reopened at the annual conference in three weeks’ time.
4.93 At is also used with ages, stages of development, and points within a larger period of time.
At the age of twenty, she married another Spanish dancer.
He left school at seventeen.
At an early stage of the war the British Government began recruiting a team of top mathematicians and electronics experts.
We were due to return to the United Kingdom at the beginning of March.
in for periods of time
4.94 If you want to mention the period of time in which something happens, you use in with centuries, years, seasons, months, and the periods of the day morning, afternoon, and evening. You also use in with daytime and night-time.
In the sixteenth century there were three tennis courts.
It’s true that we expected a great deal in the sixties.
Americans visiting Sweden in the early 1950s were astounded by its cleanliness.
If you were to go on holiday on the continent in wintertime what sport could you take part in?
To be in Cornwall at any time is a pleasure; to be here in summer is a bonus.
It’s a lot cooler in the autumn.