How Many Days Until Summer Calculator
Count exact days remaining until the first day of summer for your hemisphere. Enter values for instant results with step-by-step formulas.
Reviewed by Daniel Agrici, Founder & Lead Developer
Formula
Days Until Summer = Summer Solstice Date - Current Date
The summer solstice occurs around June 20-21 in the Northern Hemisphere and December 21-22 in the Southern Hemisphere. The calculator finds the next upcoming summer start date relative to your reference date and computes the difference in days, weeks, months, hours, and minutes.
Worked Examples
Example 1: Counting Down from March 1
Problem:It is March 1 in the Northern Hemisphere. How many days until the first day of summer (June 20)?
Solution:From March 1 to June 20:\nMarch: 31 - 1 = 30 days remaining\nApril: 30 days\nMay: 31 days\nJune 1-20: 20 days\nTotal = 30 + 30 + 31 + 20 = 111 days\nWeeks = 111 / 7 = 15 weeks and 6 days\nMonths = approximately 3.6 months
Result:111 days | 15 weeks 6 days | ~3.6 months until summer
Example 2: Southern Hemisphere Summer Countdown
Problem:It is September 15 in Australia (Southern Hemisphere). How many days until summer starts on December 21?
Solution:From September 15 to December 21:\nSeptember: 30 - 15 = 15 days remaining\nOctober: 31 days\nNovember: 30 days\nDecember 1-21: 21 days\nTotal = 15 + 31 + 30 + 21 = 97 days\nWeeks = 97 / 7 = 13 weeks and 6 days\nMonths = approximately 3.2 months
Result:97 days | 13 weeks 6 days | ~3.2 months until summer
Frequently Asked Questions
When is the first day of summer?
The first day of summer in the Northern Hemisphere is the summer solstice, which typically falls on June 20 or 21 each year. This is the longest day of the year when the sun reaches its highest point in the sky. In the Southern Hemisphere, summer begins on December 21 or 22, which is the winter solstice in the north. The exact date varies slightly each year because the Earth orbit around the sun takes approximately 365.25 days, causing calendar dates to shift. Meteorological summer, used by weather services, begins on June 1 in the Northern Hemisphere and December 1 in the Southern Hemisphere.
What is the difference between astronomical and meteorological summer?
Astronomical summer is defined by the Earth position relative to the sun, beginning on the summer solstice (around June 20-21 in the Northern Hemisphere) and ending on the autumnal equinox (around September 22-23). Meteorological summer is defined by calendar months for simpler weather record-keeping, running from June 1 through August 31 in the Northern Hemisphere. Meteorologists prefer this definition because it aligns with temperature patterns and makes seasonal comparisons more consistent. How Many Days Until Summer Calculator uses the astronomical definition based on the solstice, which is what most people think of as the official start of summer. The difference between the two definitions is typically about 3 weeks at the start.
Why does the summer solstice date change each year?
The summer solstice date shifts slightly each year because Earth takes approximately 365.2422 days to orbit the sun, not exactly 365 days. This fractional difference means the solstice can fall on June 20, 21, or rarely June 22 depending on the year. Leap years add a day to February every four years to compensate for this drift, which shifts the solstice earlier by about one day. Century years that are not divisible by 400, like 1900 and 2100, skip the leap day, causing additional variation. The Gregorian calendar system keeps the solstice within a narrow two-day window, but over centuries the exact timing gradually shifts before being corrected by leap year adjustments.
How long does summer last?
Astronomical summer lasts approximately 93 days and 15 hours in the Northern Hemisphere, making it the longest season of the year. This is because Earth is near its farthest point from the sun during Northern Hemisphere summer, causing it to move more slowly in its orbit. In the Southern Hemisphere, summer is slightly shorter at about 89 days because Earth is closer to the sun during that period and moves faster. Meteorological summer is exactly 92 days, covering June, July, and August. The perceived length of summer varies by latitude, with regions closer to the poles experiencing longer days but shorter warm periods, while tropical regions have relatively consistent day length year-round.
References
Reviewed by Daniel Agrici, Founder & Lead Developer · Editorial policy