Which novel's opening line mentions a bright cold day in April and clocks striking thirteen?

1984 (MCMLXXXIV) was a leap year starting on Sunday of the Gregorian calendar, the 1984th year of the Common Era (CE) and Anno Domini (AD) designations, the 984th year of the 2nd millennium, the 84th year of the 20th century, and the 5th year of the 1980s decade.