23 October to 21 November
The arc is two hundred and ten to two hundred and forty degrees of ecliptic longitude, which currently corresponds to 22 or 23 October through 21 or 22 November. The degrees are fixed and the dates are what the degrees happen to fall on in a given year.
Because the Sun takes about six hours longer than a calendar year to complete its circuit, both crossings arrive progressively later until the leap day resets them. The full excursion is close to a day and a half, which is why one table prints the 23rd and another the 22nd.
Ophiuchus, and why it changes nothing here
These dates draw the thirteenth sign argument more than any others. The Sun does pass through the constellation Ophiuchus in late November, and it spends only about a week inside the borders of Scorpius as astronomers draw them.
Both statements are true and neither affects the sign. Constellations are unequal patches of sky whose modern boundaries date from the nineteen twenties; signs are twelve equal divisions of thirty degrees measured from the equinox. They share names for historical reasons and have not shared positions for a long time.
A fixed water season in the middle of the autumn quarter
Scorpio sits between the September equinox and the December solstice, at neither of them, which is what a fixed sign does. The Sun's southern declination increases throughout, and in the north the month is the steepest part of the decline into winter.
Mars is the traditional ruler; modern practice adds Pluto, which is a twentieth century assignment rather than part of the classical scheme. The sign has no exaltation, and its decans fall to Mars, the Sun and Venus.
What has to be calculated instead
For a birth close to either edge, the year, the clock time and the birthplace are the only reliable inputs, and they yield a single sign with no partial or blended outcome available.
Sidereal astrology gives a different answer again, placing most of this range in Libra, since it counts from the stars while the Western zodiac counts from the equinox and the two anchors are now about twenty four degrees apart. That is a little over three weeks of solar motion.
Questions people ask about this
What are the Scorpio dates?
Approximately 23 October to 21 November. The exact start falls on 22 or 23 October and the end on 21 or 22 November, varying with the year and with the time zone the birth is dated in.
Why do the dates change from year to year?
Because the tropical year is not a whole number of days. The ingress slips about six hours later each year and is pulled back by each leap day, so it oscillates across roughly a day and a half.
When is Scorpio season this year?
Within the range above, at a minute that has to be calculated for the specific year. Anyone born close to either edge needs the actual solar position rather than a table.
Why does Vedic astrology not make me Scorpio?
It measures from the fixed stars rather than from the equinox, and the two references have separated by about twenty four degrees. That moves every sidereal boundary later by a little over three weeks.
Does being born on the first day of Scorpio mean anything special?
It puts the Sun in the first degree of the sign, which matters for aspects and house placement. The tradition does not read it as a weaker or stronger version of the sign itself.