While the upcoming weather pattern seems to be “falling back” toward winter, we still “spring forward” when daylight saving time returns this weekend. At 2 a.m. Eastern time Sunday (March 12), clocks move ahead one hour as we leave standard time behind until November.
In most of the United States, daylight saving time will push sunrise back to 7 a.m. or later, about as late as we saw in January. However, unlike two months ago, we now have nearly 12 hours of daylight as we approach the spring equinox. In exchange for darker mornings, we’ll see even more evening light: once we “spring forward,” the sun won’t set until 7 p.m. or later in many parts of the country.
How do sunrise times change after daylight saving time begins?
Since 2007, daylight saving time has been observed from the second Sunday in March until the first Sunday in November. The March start date coincides with our fastest weekly gains in morning and evening daylight. This means the darker mornings we experience after the time change will only last a few weeks.
The table below shows how much earlier the sun rises between March 12 — our first day of daylight saving time — and the summer solstice on June 21.
The change in sunrise is affected by latitude (greater in the north and more gradual in the southern U.S.). In Washington, D.C., sunrise will arrive 1 hour 41 minutes earlier over the next three months. Seattle and Minneapolis will gain more than 2 hours of morning light, while in Los Angeles, Atlanta, Houston and Miami the difference is less than 90 minutes.
If we abolished daylight saving time and stayed on standard time all year, the total amount of daylight would not change. However, it would mean sunrise would occur an hour earlier during summer. With year-round standard time, Washington would see sunrise at 4:43 a.m. on the summer solstice. In Boston, sunrise would be at 4:11 a.m. instead of 5:11 a.m., and in Chicago the sun would rise at 4:15 instead of 5:15 a.m.
How do sunset times change after daylight saving time begins?
The start of daylight saving time feels like flipping on a light switch: it immediately brightens our evenings. While sleep experts say this disrupts our circadian rhythms, a majority of Americans still seem to prefer having more sunlight after work. After we spring forward, sunset continues to advance later until the summer solstice (as shown below).
Sunset times change at a slightly slower pace than sunrise over the next three months. (For example, Washington, D.C., gains 1 hour 41 minutes of morning light, but only 1 hour 25 minutes in the evening.)
Without daylight saving time, sunset on June 21 — the longest day of the year — would occur before 8 p.m. in most of the country. If we stayed on year-round standard time, Washington, D.C.'s sunset would be at 7:36 p.m. instead of 8:36 p.m. on the summer solstice. In Boston and Chicago, the latest sunset of the year would occur before 7:30 p.m.
When do we recover the lost hour of morning daylight?
After daylight saving time begins Sunday, we’ll be getting up in the dark — but in a few weeks, mornings will turn brighter again. The table below shows when different cities regain the lost hour of morning light. As daylight continues to increase, it will take little over a month until sunrise “catches up” to the same time we see the day before the time change.
How long it takes to regain the lost hour of morning light depends on latitude. The northern tier regains an hour of morning light in only 4 to 5 weeks, while in the South — where daylight changes more slowly — it can take about 7 weeks or longer.
Sunrise in Washington, D.C., on March 11 is at 6:25 a.m. After daylight saving time begins, the sun won’t rise that early again in the nation’s capital until April 19, more than five weeks later. In Miami, Saturday’s 6:34 a.m. sunrise won’t be matched again until May 16.
How long does it take to recover the lost hour of daylight in the morning after the change to Daylight Saving Time??? pic.twitter.com/4HojRHbat1— Brian Brettschneider (@Climatologist49) March 11, 2018
The return of morning light is inevitable as we head into spring. Without daylight saving time, many parts of the country would see sunrise before 6 a.m. for several months of the year. If you generally prefer more evening light and would rather not be awakened by the sun before 5 a.m. during the summer months, then daylight saving time is arguably worth keeping.