"First" and "Last" Events of the Season 
(see notes below the table for more info on the categories)
Event
1999-2000
2000-2001
 2001-2002 2002-2003 2003-2004 2004-2005 2005-2006 2006-2007 2007-2008
First Frost Aug. 30 Sept 5 (a) Sept 14 Oct 10 Sept 5 Sept 29 Sept 23 Sept 10 Oct 11
First Hard Freeze Oct. 3 Sept 28 Sept 29 Oct 3 Oct 2 Sept 29 Oct 9 Oct 6 Oct 25
First Flakes Oct. 2 Oct. 6 Oct 6 Oct 13 Sept 30 Oct 4 Oct 7 Oct 11 Oct 24
First Trace of Snow Oct. 2 Oct. 7 Oct 6 Oct 13 Sept 30 Oct 16 Nov 16 Oct 11 Oct 24
First 1" of Snow Nov. 23 Oct. 7 Oct 6 Oct 13 Nov 4 Oct 16 Nov 16 Oct 11 Nov 6
Groomers in Action Dec. 21  Dec 7 Dec. 26 Dec 8 Dec 10 Dec 2 Dec 2 Dec 6 Dec 1
Snowfall by Jan. 1 54.5"  134" 71" 68.5" 64.0" 82" 125" 34.5" 91.5"
Snowfall by March 31 144.2" 301.6" 246"  220" 228.5" 201" 246.5" 161.5" 234.0"
Total For Season 152.7" 303.6" 252.0" 225.0" 232.0" 202.5" 247.5" 205.5" 256.5"
Grooming Ends Feb 21 ! March 31 April 7  March 14 March 24 March 30 March 28 March 14 April 6
Last Snowfall April 17 April 23 May 8 April 3 April 3 May 2 March 13 April 7 May 3
Last Ride March 28 Feb 4 (b)  April 16 March 29(c) April 3 April 9 April 9 April 14 April 12
Last Flakes April 28 April 23  May 19 April 5 April 27 May 11 May 12 May 20 May 26
Last day with snow on ground. April 17 April 23 May 9 April 18 April 15 May 2 April 11 April 20 May 7
Laurium Glacier Melts N/A May 18  May 22 May 26 May 25 May 15 May 15 May 18 May 28
    "First Frost" is the first sign of frost in Lake Linden outside John Dee's house (usually seen on the roof top of neighbors house!).  Many times a frost will occur with temps above freezing and it is possible to have a hard freeze occur without frost forming.
    "First Hard Freeze" is defined as the first time the temperature dips below freezing.  A hard freeze is usually defined as temps of 28 or below, as this in the threshold for many plants before they die.  I will just stick to temps below 32 for this purpose.
    "First Flakes" represents the first flakes of the season seen by John Dee in the Keweenaw.  Some snow may fall in the higher elevations before I see it, but that does not count in this case.  Also the flakes only have to be seen, not accumulate.  The first accumulation is defined here as "First Trace of Snow".
    "Groomers in Action" defines the first day that the snowmobile trail groomers take to the trails (the earliest it can be any year is December 1 as that is when the trails open).  "Grooming Ends" is just the opposite and the last day that can possibly be is March 31 as that is the last day they will be paid to groom.
    "Last Snowfall" is the latest date when snow falls and accumulates to at least an inch.
    "Last Ride" is the last ride taken by John Dee (on snow!)

FOOT NOTES:
Data up until Spring of 2006 was for Lake Linden, after that for Allouez Township in Keweenaw County
(*) Not final yet
(a) A very scattered frost occurred July 19, but was so localized I decided not to count it.
(b) I broke my leg on this day, but friends were riding on April 19th.
(c) I broke the sled, but could have ridden until about April 10th.