Bay Area Storm Index (BASI)
ARCHIVE

Jan Null, CCM
Golden Gate Weather Services

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All Storms greater than 6.0 since 1950

    SF City SFO Max Bay Area Max
24-hour Rain   Sustained Wind Wind Gust*
Date BASI in. pts mph pts mph pts
11/18/1950 8.2 1.88 3.3 36 2.6 71 2.3
12/1/1951 8.7 1.59 3.0 43 3.0 85 2.7
12/3/1951 8.2 1.58 3.0 38 2.8 76 2.4
1/14/1952 8.7 1.71 3.2 41 3.0 83 2.5
12/22/1955 9.8 2.57 4.0 42 3.0 90 2.8
12/23/1955 9.1 2.18 3.6 41 3.0 83 2.5
1/12/1957 6.8 1.25 1.8 37 2.7 74 2.3
1/5/1959 7.2 1.44 2.6 35 2.5 69 2.1
9/18/1959 8.4 2.01 3.5 36 2.6 71 2.3
12/1/1960 8.8 1.68 3.1 44 3.0 87 2.7
10/12/1962 9.7 3.11 4.0 43 3.0 86 2.7
10/13/1962 9.5 3.56 4.0 41 3.0 83 2.5
1/30/1963 9.3 1.87 3.3 51 3.0 101 3.0
1/31/1963 7.3 1.26 2.0 39 2.9 78 2.4
1/20/1964 9.1 1.86 3.3 45 3.0 90 2.8
1/21/1967 9.2 2.45 3.9 39 2.9 78 2.4
11/13/1981 8.3 1.43 2.6 45 3.0 89 2.7
3/31/1982 9.5 2.57 4.0 40 3.0 81 2.5
12/22/1982 9.3 2.00 3.5 47 3.0 94 2.8
11/12/1984 7.7 1.68 3.1 35 2.5 69 2.1
2/8/1985 7.8 1.70 3.2 35 2.5 69 2.1
2/14/1986 9.2 1.83 3.3 48 3.0 97 2.9
2/15/1986 8.8 1.88 3.3 41 3.0 83 2.5
2/16/1986 8.2 1.74 3.2 37 2.7 74 2.3
2/17/1986 8.8 1.68 3.1 44 3.0 87 2.7
2/18/1986 9.0 1.87 3.3 44 3.0 87 2.7
2/13/1987 8.6 2.22 3.7 36 2.6 71 2.3
2/16/1990 8.6 1.40 2.6 55 3.0 110 3.0
1/13/1993 8.4 1.94 3.4 37 2.7 74 2.3
1/10/1995 6.8 1.33 2.2 35 2.5 69 2.1
3/22/1995 6.6 1.28 2.0 35 2.5 69 2.1
12/11/1995 9.7 3.61 4.0 43 3.0 85 2.7
12/12/1995 10.0 3.27 4.0 54 3.0 108 3.0
1/16/1996 6.6 1.27 2.0 35 2.5 69 2.1
1/1/1997 8.3 2.00 3.5 35 2.5 70 2.3
2/3/1998 8.0 3.00 4.0 30 2.0 60 2.0
2/14/2000 9.3 2.50 4.0 39 2.9 79 2.4
12/1/2001 7.8 2.00 3.5 32 2.2 65 2.1
12/2/2001 8.8 2.14 3.6 38 2.8 76 2.4
11/7/2002 8.7 1.47 2.8 40 3.0 96 2.9
12/16/2002 9.3 2.07 3.5 43 3.0 91 2.8
12/29/2003 7.9 2.15 3.6 33 2.3 61 2.0
1/1/2004 8.6 1.84 3.3 44 3.0 72 2.3
2/25/2004 8.6 2.01 3.5 38 2.8 73 2.3
12/1/2005 7.1 1.16 1.6 43 3.0 81 2.5
12/18/2005 8.9 2.99 4.0 36 2.6 71 2.3
12/31/2005 9.2 2.80 4.0 38 2.8 77 2.4
2/27/2006 7.9 1.29 2.0 55 3.0 97 2.9
1/4/2008 9.2 2.01 3.5 53 3.0 87 2.7
10/13/2009 9.3 2.48 3.9 41 3.0 77 2.4
12/28/2010 6.7 1.30 2.2 35 2.5 60 2.0
3/24/2011 7.3 1.56 3.0 33 2.3 61 2.0
12/11/2014 8.2 3.40 4.0 29 1.9 71 2.3
1/8/2017 8.5 1.62 3.1 44 3.0 77 2.4
2/20/2017 6.3 1.84 3.3 25 1.5 53 1.5


Criteria Used to Calculate BASI

San Francisco
24-hour Rain

SF Airport Max
Sustained Wind

Max Bay Area
Wind Gust (below 1500')

Criteria Points
2.50" or more4
2.40" to 2.49"3.9
2.30" to 2.39"3.8
2.20" to 2.29"3.7
2.10" to 2.19"3.6
2.00" to 2.09"3.5
1.90" to 1.99"3.4
1.80" to 1.89"3.3
1.70" to 1.79"3.2
1.60" to 1.69"3.1
1.50" to 1.59"3.0
1.45" to 1.49"2.8
1.40" to 1.44"2.6
1.35" to 1.39"2.4
1.30" to 1.34"2.2
1.25" to 1.29"2.0
1.20" to 1.24"1.8
1.15" to 1.19"1.6
1.10" to 1.14"1.4
1.05" to 1.09"1.2
1.00" to 1.04"1.0
0.95" to 0.99"0.9
0.90" to 0.94"0.8
0.85" to 0.89"0.7
0.80" to 0.84"0.6
0.75" to 0.79"0.5
CriteriaPoints
40 mph or more 3
392.9
38 2.8
372.7
36 2.6
352.5
34 2.4
332.3
32 2.2
312.1
30 2
291.9
28 1.8
271.7
26 1.6
251.5
24 1.4
231.3
22 1.2
211.1
20 1
CriteriaPoints
100 mph or more3
95 mph to 99 mph2.875
90 mph to 94 mph2.75
85 mph to 89 mph2.675
80 mph to 84 mph2.5
75 mph to 79 mph2.375
70 mph to 74 mph2.25
65 mph to 69 mph2.125
60 mph to 64 mph2.0
55 mph to 59 mph1.75
50 mph to 54 mph1.5
45 mph to 49 mph1.25
40 mph to 44 mph1.00
Less than 40 mph0

* below 1500' elevation
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o Bay Area Storm Index

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