Late in a sign is not the same as near a boundary
People often hear that a birthday falls at the end of a sign and assume the answer is shaky. The two ideas are separate. What matters is the distance in time to the ingress, and from twenty six degrees the Sun still has about four degrees to travel, which takes it roughly four days.
Since the position on a fixed date only wanders by about a degree and a half across a century, no year comes anywhere near closing that gap. A 15 February birth is Aquarius in every year on record and will stay so for a long time yet.
The confusion usually comes from the habit of printing sign dates as fixed ranges. A range with hard edges invites the reader to imagine a rule that switches over at midnight, when in fact the change happens at a specific instant that shifts by hours from year to year.
What the last degrees of a sign carry
Twenty six degrees is well inside the third decan, the band from twenty to thirty that the Chaldean order gives to the Moon. Some older material treats the final degrees of any sign as a place of handing over, where the sign's business is finishing rather than beginning.
That is a traditional reading and should be marked as one. In technical terms a Sun at twenty six degrees is exactly as much in Aquarius as a Sun at six, and the only measurable consequence of the higher figure is which aspects it forms with other bodies in the chart.
Why the position holds year after year
The calendar runs slightly short of the tropical year, so the Sun's longitude on a fixed date advances by around a quarter of a degree annually. The leap day undoes that accumulation, pulling the date back by close to a full day and returning the Sun to nearly its earlier place.
The pattern is a small sawtooth rather than a drift, which is why an ephemeris for 1935 and one for 2030 will agree on this date to within a degree and a half. Your own year decides where inside that narrow band you fall.
The century rule refines the correction further by skipping the leap day in most years divisible by a hundred. Over the span from 1930 to 2035 only the year 2000 was affected, and it kept its leap day, so the pattern here is undisturbed.
The faster placements, which the date cannot fix
The Moon covers about thirteen degrees a day, so it changes sign every two and a half days and will be in one of two signs on any given 15 February, depending on the hour and the time zone. The rising sign turns through all twelve signs in a day, so it is open until a birth time and place are supplied.
The widget above computes the exact solar degree for your year and birthplace and reports how far your birth fell from the nearest sign boundary. Here the answer will be about four days, which is enough to settle the sign without argument.
Beyond those, the house framework rests entirely on the horizon, so an unknown birth time leaves most of a chart unbuilt even when the Sun is certain.
Questions people ask about this
Is 15 February Aquarius or Pisces?
Aquarius. The Sun crosses into Pisces around 18 or 19 February, so this date sits about four days clear of the change in every year.
Does being late in a sign weaken it?
No. Membership of a sign is not graded by degree. The figure affects aspects and house placement rather than whether the sign applies.
What degree is the Sun on this date?
Around twenty six degrees of Aquarius, within a window a little over a degree wide across the last century at noon.
What is the decan here?
The third decan of Aquarius, twenty to thirty degrees, which the Chaldean order assigns to the Moon.
Could a different time zone change my sign?
Not on this date. Time zones shift a birth by hours at most, and the nearest boundary is several days away.
What actually differs between two people born on this date?
Usually the Moon, the Ascendant and the entire house structure, since all of those depend on the hour and the place rather than the calendar date.