The figure, and how firm it is
Noon positions on 5 September have fallen between about 12.0 and 13.4 degrees of Virgo in every year from 1930 to 2035. The thirteenth degree covers most births on the date, and the band is narrow for the same reason it is narrow on every fixed date, namely that the leap year rule keeps the calendar tracking the orbit instead of sliding away from it.
What decides your place inside the band is the year, the hour and the meridian of the birthplace, since a local clock reading has to be converted to a universal instant before the Sun's longitude can be worked out. The widget above handles that conversion and returns the result to minutes of arc.
An hour recorded to the nearest quarter of an hour is enough for most purposes here, since the Sun moves only a couple of arcminutes in that time. The Ascendant is the placement that punishes a vague birth time, not the Sun.
What a degree is for
Sign membership is a coarse fact. The degree is what aspects are measured from, and aspects are most of what a working chart consists of. A planet near thirteen degrees of Pisces opposes this Sun, one near thirteen degrees of Taurus or Capricorn trines it, and one near thirteen degrees of Gemini or Sagittarius squares it.
Those relationships hold whatever hour you were born at, which makes them the part of a chart that survives a missing birth time. Progressions and solar returns also start from the exact longitude. None of it can be read from the word Virgo, which is why the degree is the more useful thing to know.
The face around it
Thirteen degrees sits in the middle of Virgo's second decan, the band from ten to twenty. The Chaldean order, looping Mars, Sun, Venus, Mercury, Moon, Saturn and Jupiter from the start of Aries, hands that face to Venus. The triplicity order, taking the earth signs Taurus, Virgo and Capricorn in sequence, hands it to Capricorn and so to Saturn.
Traditionally the face is read as a modifier rather than a substitute. Virgo remains mutable earth under Mercury, and the face tilts the description towards form and proportion under one scheme or towards structure and patience under the other. Both are interpretation attached to a measured band, and neither says anything about fortune.
What the date will never tell you
The Moon covers roughly thirteen degrees of the zodiac each day, so on any 5 September it occupies one of two signs and the hour decides which one. The date narrows the field and no more. The Ascendant runs the whole circle daily, so all twelve signs remain available, and it shifts by a degree for every four minutes of birth time.
Because the house cusps are built from the Ascendant, a chart without a birth time has planets at known longitudes and nowhere to put them. That is the honest limit of a birthday page. It can give you a precise Sun and an accurate face, and it cannot give you the frame those sit in.
Questions people ask about this
What sign is 5 September?
Virgo, and not near an edge. The Sun is around thirteen degrees into the sign, with the Leo boundary a fortnight behind and the Libra boundary a fortnight ahead.
What degree is the Sun on 5 September?
Close to thirteen degrees of Virgo. Noon values across 1930 to 2035 run from about 12.0 to 13.4, and your own figure inside that band depends on your year, hour and birthplace.
Which decan does this fall in?
Virgo's second face, from ten to twenty degrees, with the Sun near its centre. That face answers to Venus in the Chaldean scheme and to Saturn in the triplicity scheme.
Why does the exact degree matter?
Because aspects, progressions and solar returns are all measured from it. Two Virgos ten degrees apart make entirely different aspects to the same planet, which sign level description cannot capture.
Can I work out my Moon sign from the date?
Only to two candidates, since the Moon crosses about half a sign in a day. Choosing between them needs the hour, and the pair itself changes from year to year.
What is missing without a birth time?
The Ascendant and every house cusp, and often the Moon. The Sun's longitude and the aspects to it stay reliable, so an untimed chart is partial rather than useless.