QUESTION:
QA: South Pole

What are  the general  weather conditions at Mars' south pole during early
summer?  Is it the dust storm season, or are things generally calm at 
that time?

ANSWER from Bruce Jakosky on September 6, 1999:
Southern-hemisphere summer is historically the time that global dust
storms occur.  I suspect that you are asking about the conditions that
will be present at the time of the Mars Polar Lander landing on December
3rd.  At that time, the sun is almost as high above the horizon as it's
going to get, and it will stay high for a couple of months before it begins
to drop.  If there is a global dust storm at the time of the landing, it
is unlikely that much dust will be carried as far south as where the landing
will occur; historically, the polare regions have remained relatively clear
even while global dust storms are occurring, and they are the first places
to clear up afterwards.

While the landing site should be free of solid CO2 ice on the ground, the
residual polar cap itself should still be covered with CO2 ice.  As the
CO2 ice has very low temperatures, the contrast between the "covered"
and "uncovered" ground should drive strong winds at the vicinity of the edge
of the cap.  The landing site, however, should be far enough away from this
boundary that it would not be affected.

However, one thing that we've discovered is that every Mars year is different
in some ways from every other one, and Mars always has surprises in store
for us.  Thus, we cannot know until the time of the landing what the conditions
will be.