Los Gatos B&B
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Los Gatos B&B clear sky chart from 2005-11-06 to 2024-01-27.

This page is a summary of past forecasts. Even though it's based only on forecasts, some people use these pages as clue to a site's climate. But climate data based on actual observation should be preferred (if you can find it!).

Cloud, Transparency and Seeing forecasts are summarized individually. But because good observing conditions require a combination of minimum cloud cover, transparency and seeing, the individual forecast summaries can be difficult to interpret. The observing conditions section counts the combinations of conditions needed for common types of astronomical observation.

Observing Conditions

The following tables count the occurrence of the combinations of forecast and darkness conditions needed for different observations. Conditions are rated by by what percentage of the hours the observation would likely be attempted are usable.
Observation TypeMinimum conditions for hour to be usableOut of hours
Clear of CloudsTransparencySeeingSky Brightness
Planetary:50%(no limit)Average(no limit)Nighttime Hours
Deep Sky:70%Average(no limit)5.9Nighttime Hours
CCD Imaging:70%Below AveragePoor(no limit)Nighttime Hours

Percentages are of nighttime hours per month, or per year, when a particular observing conditions was met. Deep Sky percentages never exceed 50% because the moon is up half the time. Deep sky percentages are much lower for charts at high latitudes because of fewer dark hours in the summer.

Overall

PlanetaryData
Pts
Deep Sky
Max 60%
Data
Pts
Both Planetary and Deep Sky
Max 60%
Data
Pts
Either Planetary or Deep SkyData
Pts
CCD ImagingData
Pts
Night
29%
22962
13%
74974
8%
22916
35%
22916
15%
54200

By Month

MonthDays of MonthPlanetaryData
Pts
Deep Sky
Max 60%
Data
Pts
Both Planetary and Deep Sky
Max 60%
Data
Pts
Either Planetary or Deep SkyData
Pts
CCD ImagingData
Pts
January1st to 10thNight
11%
759
8%
2649
4%
757
17%
757
6%
2145
January11th to 20thNight
15%
760
7%
2615
4%
760
19%
760
7%
2164
January21st to endNight
14%
820
9%
2664
4%
820
20%
820
8%
2147
February1st to 10thNight
11%
720
8%
2340
2%
720
18%
720
8%
1852
February11th to 20thNight
12%
703
9%
2275
2%
700
20%
700
8%
1781
February21st to endNight
14%
592
11%
1784
4%
592
23%
592
10%
1391
March1st to 10thNight
17%
720
12%
2066
6%
720
24%
720
12%
1599
March11th to 20thNight
20%
720
14%
1980
7%
720
26%
720
14%
1496
March21st to endNight
21%
792
15%
2120
6%
792
28%
792
17%
1600
April1st to 10thNight
21%
720
14%
1800
4%
720
27%
720
18%
1346
April11th to 20thNight
26%
711
14%
1775
6%
711
29%
711
21%
1314
April21st to endNight
30%
662
16%
1742
6%
662
36%
662
22%
1245
May1st to 10thNight
37%
451
14%
1531
9%
451
42%
451
15%
1070
May11th to 20thNight
38%
354
19%
1416
16%
354
48%
354
20%
869
May21st to endNight
46%
388
15%
1551
15%
388
53%
388
22%
910
June1st to 10thNight
43%
360
16%
1440
16%
360
53%
360
20%
892
June11th to 20thNight
46%
360
14%
1440
15%
360
53%
360
20%
851
June21st to endNight
51%
360
15%
1440
17%
360
58%
360
22%
849
July1st to 10thNight
60%
350
15%
1400
19%
350
64%
350
25%
816
July11th to 20thNight
57%
348
18%
1392
25%
348
61%
348
26%
784
July21st to endNight
55%
443
17%
1533
16%
419
58%
419
25%
930
August1st to 10thNight
56%
537
17%
1600
13%
534
60%
534
31%
983
August11th to 20thNight
56%
538
17%
1602
12%
538
59%
538
28%
1033
August21st to endNight
55%
792
20%
1980
11%
792
58%
792
34%
1294
September1st to 10thNight
48%
720
16%
1800
8%
720
52%
720
31%
1206
September11th to 20thNight
50%
720
23%
1800
15%
720
54%
720
33%
1186
September21st to endNight
43%
720
19%
2060
15%
720
47%
720
25%
1380
October1st to 10thNight
34%
720
13%
2160
10%
720
39%
720
20%
1497
October11th to 20thNight
28%
720
13%
2160
8%
720
36%
720
18%
1502
October21st to endNight
18%
792
13%
2401
6%
792
27%
792
13%
1832
November1st to 10thNight
28%
740
17%
2407
11%
740
36%
740
18%
1648
November11th to 20thNight
21%
760
15%
2624
9%
760
29%
760
14%
1849
November21st to endNight
20%
760
10%
2660
5%
760
27%
760
11%
2004
December1st to 10thNight
15%
760
6%
2660
3%
760
19%
760
7%
2128
December11th to 20thNight
13%
759
7%
3250
2%
759
18%
759
5%
2550
December21st to endNight
10%
831
4%
4857
2%
817
16%
817
3%
4057

Individual Forecasts

The length of each colored bar in the "occurrence of each Forecast" column is proportional to the number of times the chart forecast that color. The percentages are of the total number of hours per month, or per year, with a particular forecast. The colors as the same as those used in clear sky charts.

Note: Transparency probabilities are only counted for those hours that have 30% or less cloud cover. Seeing probabilities are only counted for those hours that have 80% or less cloud cover. If that's too tricky, try Observing Conditions instead.

Overall

Occurrence of each ForecastData
Points
Cloud CoverDay
14%10%48%7%45%5%6%7%30%
74824
Night
15%10%48%7%45%5%6%7%31%
75213
TransparencyDay
52%8%12%18%9%1
74533
Night
52%8%13%18%9%1
75039
SeeingDay
21%16%30%20%10%3
13544
Night
20%15%30%24%9%1
22970

By Month

Percentage Cloud Cover NE (2006-)
Color Meanings:
Overcast 90% covered 80% covered 70% covered 60% covered 50% covered 40% covered 30% covered 20% covered 10% covered Clear
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 10thDay
10%17%7%11%10%5%7%6%5%5%17%
1517
11th to 20thDay
13%17%7%13%10%46%5%6%415%
1562
21st to endDay
10%14%8%14%13%5%6%5%5%5%14%
1836
February1st to 10thDay
16%16%7%11%10%46%5%4417%
1620
11th to 20thDay
11%16%8%15%9%46%5%45%18%
1573
21st to endDay
18%13%5%12%10%44445%21%
1471
March1st to 10thDay
12%12%8%12%8%45%45%6%23%
1887
11th to 20thDay
13%14%6%10%7%25%445%28%
1980
21st to endDay
17%11%5%9%7%3445%6%28%
2235
April1st to 10thDay
15%12%5%7%7%35%46%7%29%
2160
11th to 20thDay
17%10%47%6%345%5%6%35%
2134
21st to endDay
19%10%47%6%35%45%7%32%
2232
May1st to 10thDay
15%10%47%7%46%446%33%
2426
11th to 20thDay
15%7%36%6%45%6%6%8%35%
2478
21st to endDay
12%5%26%7%46%7%5%8%39%
2725
June1st to 10thDay
16%6%36%5%35%6%6%8%35%
2520
11th to 20thDay
13%5%26%6%45%6%7%9%37%
2520
21st to endDay
11%5%36%6%46%6%6%9%38%
2520
July1st to 10thDay
9%5%36%6%46%5%7%10%40%
2520
11th to 20thDay
10%5%25%7%46%6%8%9%37%
2520
21st to endDay
10%5%36%7%48%6%7%9%35%
2690
August1st to 10thDay
10%5%26%7%46%7%6%10%37%
2327
11th to 20thDay
11%7%27%7%5%7%6%8%9%31%
2281
21st to endDay
13%6%37%7%46%5%7%9%33%
2376
September1st to 10thDay
15%6%35%5%35%6%6%8%37%
2160
11th to 20thDay
13%6%35%5%45%46%7%43%
2160
21st to endDay
16%6%37%7%36%5%6%7%35%
1897
October1st to 10thDay
18%7%38%6%445%7%7%33%
1800
11th to 20thDay
19%9%37%7%45%5%6%7%29%
1800
21st to endDay
23%12%48%5%45%45%6%24%
1954
November1st to 10thDay
12%11%48%7%46%5%46%33%
1671
11th to 20thDay
12%13%5%8%7%5%5%6%6%7%26%
1554
21st to endDay
16%14%410%8%45%5%6%6%23%
1520
December1st to 10thDay
16%18%7%12%7%35%5%5%5%18%
1520
11th to 20thDay
17%15%7%11%7%45%5%6%5%19%
1906
21st to endDay
22%20%6%11%7%35%44412%
2772
January1st to 10thNight
13%14%6%12%9%5%6%6%5%6%17%
2649
11th to 20thNight
14%16%7%13%10%45%5%5%5%17%
2615
21st to endNight
11%12%6%12%11%5%7%5%5%7%19%
2664
February1st to 10thNight
14%15%7%11%7%45%5%6%5%21%
2340
11th to 20thNight
11%12%6%13%9%5%6%5%5%6%21%
2273
21st to endNight
16%10%411%9%46%5%5%7%23%
1784
March1st to 10thNight
12%12%7%10%8%5%5%5%6%6%25%
2056
11th to 20thNight
16%11%5%9%7%345%5%6%29%
1979
21st to endNight
16%12%5%8%6%36%45%5%31%
2120
April1st to 10thNight
16%10%47%6%35%5%6%7%31%
1800
11th to 20thNight
17%10%47%6%3445%6%36%
1775
21st to endNight
16%7%47%6%445%6%7%35%
1742
May1st to 10thNight
17%9%36%5%5%5%5%5%7%32%
1531
11th to 20thNight
11%6%26%6%35%5%7%8%40%
1415
21st to endNight
10%5%25%5%345%6%8%46%
1550
June1st to 10thNight
14%5%36%5%36%5%6%9%38%
1440
11th to 20thNight
9%5%36%6%345%6%8%44%
1440
21st to endNight
9%5%35%6%35%6%6%10%43%
1440
July1st to 10thNight
5%6%25%6%45%6%6%10%46%
1440
11th to 20thNight
10%425%4347%6%8%49%
1440
21st to endNight
12%5%35%5%35%5%7%10%41%
1623
August1st to 10thNight
8%426%5%346%6%9%47%
1611
11th to 20thNight
11%6%26%6%45%6%6%8%43%
1602
21st to endNight
10%5%25%5%35%47%9%46%
1980
September1st to 10thNight
13%5%25%5%35%5%5%8%45%
1800
11th to 20thNight
13%436%5%345%5%6%46%
1800
21st to endNight
13%7%245%446%7%8%40%
2060
October1st to 10thNight
16%8%36%6%35%46%6%37%
2160
11th to 20thNight
17%9%35%6%35%46%8%34%
2160
21st to endNight
24%9%37%6%3445%6%27%
2401
November1st to 10thNight
14%10%36%6%35%5%5%6%37%
2407
11th to 20thNight
15%10%46%7%35%5%6%8%30%
2624
21st to endNight
14%12%5%8%7%46%5%6%7%25%
2660
December1st to 10thNight
16%15%6%9%8%5%6%5%6%6%19%
2660
11th to 20thNight
17%15%6%10%8%45%445%22%
3288
21st to endNight
25%18%6%9%6%45%46%6%13%
4884

Transparency (when cloud cover <= 30%)
Color Meanings:
Too cloudy to forecast Poor Below Average Average Above average Transparent
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 10thDay
67%7%10%12%4
1518
11th to 20thDay
71%8%9%9%3
1562
21st to endDay
71%6%10%9%3
1836
February1st to 10thDay
71%6%10%10%4
1620
11th to 20thDay
69%5%7%14%4
1582
21st to endDay
66%5%10%13%6%1
1471
March1st to 10thDay
61%6%12%15%5%1
1890
11th to 20thDay
58%6%10%15%9%2
1980
21st to endDay
58%6%7%18%10%2
2235
April1st to 10thDay
55%5%10%19%9%2
2160
11th to 20thDay
50%7%10%18%14%1
2134
21st to endDay
53%5%9%19%12%2
2232
May1st to 10thDay
52%6%10%18%12%2
2426
11th to 20thDay
46%8%12%20%13%2
2482
21st to endDay
41%10%14%22%12%1
2725
June1st to 10thDay
45%8%12%20%15%1
2520
11th to 20thDay
41%9%15%23%11%1
2520
21st to endDay
41%9%14%22%13%1
2520
July1st to 10thDay
38%10%13%26%12%2
2450
11th to 20thDay
38%11%16%22%12%
2445
21st to endDay
42%11%14%22%11%1
2540
August1st to 10thDay
40%10%16%23%11%1
2314
11th to 20thDay
45%11%14%22%7%1
2281
21st to endDay
44%9%13%22%10%1
2376
September1st to 10thDay
43%8%13%24%11%1
2160
11th to 20thDay
39%6%12%25%16%1
2160
21st to endDay
46%8%12%21%12%1
1897
October1st to 10thDay
49%7%13%18%12%1
1800
11th to 20thDay
53%7%13%18%8%1
1800
21st to endDay
60%7%12%14%6%2
1954
November1st to 10thDay
51%8%13%16%11%2
1671
11th to 20thDay
55%8%13%15%7%1
1554
21st to endDay
61%7%14%14%3
1520
December1st to 10thDay
68%7%11%11%3
1520
11th to 20thDay
67%7%14%9%31
1906
21st to endDay
74%8%7%10%1
2772
January1st to 10thNight
65%8%11%10%5%
2649
11th to 20thNight
68%8%11%10%4
2615
21st to endNight
65%8%12%12%41
2664
February1st to 10thNight
63%6%12%12%5%
2340
11th to 20thNight
63%5%11%14%5%1
2275
21st to endNight
59%8%11%13%8%1
1784
March1st to 10thNight
59%6%12%17%5%1
2066
11th to 20thNight
56%6%11%18%9%1
1980
21st to endNight
55%6%10%16%12%2
2120
April1st to 10thNight
52%6%12%19%9%2
1800
11th to 20thNight
49%7%11%18%14%1
1775
21st to endNight
47%6%12%19%13%3
1742
May1st to 10thNight
52%6%11%17%11%2
1531
11th to 20thNight
40%8%13%24%14%1
1416
21st to endNight
36%9%17%22%14%2
1551
June1st to 10thNight
42%7%12%25%14%1
1440
11th to 20thNight
36%10%15%23%13%3
1440
21st to endNight
35%10%13%26%15%1
1440
July1st to 10thNight
33%10%14%24%17%3
1400
11th to 20thNight
32%10%13%28%17%1
1392
21st to endNight
36%9%15%24%15%2
1533
August1st to 10thNight
32%11%15%29%13%1
1600
11th to 20thNight
37%9%16%30%8%
1602
21st to endNight
33%9%16%27%13%2
1980
September1st to 10thNight
36%9%16%24%12%2
1800
11th to 20thNight
36%7%13%26%16%1
1800
21st to endNight
41%8%14%22%13%1
2060
October1st to 10thNight
47%8%14%18%12%1
2160
11th to 20thNight
47%8%16%18%10%1
2160
21st to endNight
59%6%13%14%7%1
2401
November1st to 10thNight
47%8%12%21%11%2
2407
11th to 20thNight
51%8%14%18%8%2
2624
21st to endNight
56%9%16%15%4
2660
December1st to 10thNight
65%7%15%11%2
2660
11th to 20thNight
65%6%11%14%4
3288
21st to endNight
71%8%9%10%1
4884

Seeing (when cloud cover <= 80%)
Color Meanings:
Too cloudy to forecast Bad 1/5 Poor 2/5 Average 3/5 Good 4/5 Excellent 5/5
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 10thDay
24%23%36%12%5%
180
11th to 20thDay
30%27%34%8%11
200
21st to endDay
23%26%38%10%3
282
February1st to 10thDay
35%30%28%8%
240
11th to 20thDay
34%26%34%6%
240
21st to endDay
33%24%29%14%1
337
March1st to 10thDay
25%25%31%16%3
420
11th to 20thDay
24%26%32%13%5%
420
21st to endDay
31%20%31%13%5%1
462
April1st to 10thDay
26%22%31%15%5%1
420
11th to 20thDay
26%22%28%13%9%2
412
21st to endDay
29%17%30%18%6%1
420
May1st to 10thDay
23%21%28%16%9%2
423
11th to 20thDay
17%15%33%23%10%2
447
21st to endDay
15%11%31%24%16%4
485
June1st to 10thDay
18%13%31%25%10%2
450
11th to 20thDay
13%12%28%32%12%3
450
21st to endDay
13%12%34%28%9%4
450
July1st to 10thDay
10%7%27%33%18%5%
445
11th to 20thDay
11%6%25%32%21%5%
444
21st to endDay
12%7%32%32%13%4
488
August1st to 10thDay
9%6%25%31%21%8%
446
11th to 20thDay
14%5%30%26%17%9%
439
21st to endDay
12%10%28%25%15%10%
495
September1st to 10thDay
18%10%24%23%16%9%
450
11th to 20thDay
11%9%24%26%19%11%
450
21st to endDay
17%14%28%21%16%5%
450
October1st to 10thDay
21%10%30%18%14%6%
450
11th to 20thDay
25%16%29%21%7%2
450
21st to endDay
29%18%31%18%4
482
November1st to 10thDay
20%21%30%19%10%1
365
11th to 20thDay
25%23%31%17%3
214
21st to endDay
24%31%32%12%1
180
December1st to 10thDay
29%19%36%11%31
180
11th to 20thDay
32%24%31%12%11
180
21st to endDay
30%21%37%12%1
198
January1st to 10thNight
24%25%33%16%3
760
11th to 20thNight
23%23%33%18%31
760
21st to endNight
19%22%38%18%3
820
February1st to 10thNight
26%23%33%18%1
720
11th to 20thNight
21%24%37%16%2
703
21st to endNight
26%22%33%16%3
592
March1st to 10thNight
23%20%35%19%3
720
11th to 20thNight
25%20%31%20%3
720
21st to endNight
24%18%32%20%6%1
792
April1st to 10thNight
23%19%32%22%3
720
11th to 20thNight
23%15%32%21%7%1
711
21st to endNight
20%13%31%26%9%
662
May1st to 10thNight
20%12%23%32%12%1
451
11th to 20thNight
14%9%34%33%10%1
354
21st to endNight
12%7%30%33%18%
389
June1st to 10thNight
16%6%29%32%18%1
360
11th to 20thNight
11%10%26%38%16%
360
21st to endNight
11%8%26%42%11%1
360
July1st to 10thNight
8%421%45%21%2
350
11th to 20thNight
11%124%40%23%1
348
21st to endNight
11%424%42%17%2
443
August1st to 10thNight
10%323%38%22%3
537
11th to 20thNight
12%5%20%36%25%4
538
21st to endNight
11%6%22%36%23%2
792
September1st to 10thNight
14%8%23%33%19%4
720
11th to 20thNight
14%7%22%28%24%5%
720
21st to endNight
15%10%26%27%18%3
720
October1st to 10thNight
19%12%29%20%17%3
720
11th to 20thNight
21%16%30%26%7%
720
21st to endNight
31%14%32%20%3
792
November1st to 10thNight
22%15%31%24%8%
740
11th to 20thNight
23%20%33%18%5%2
760
21st to endNight
22%22%29%22%41
760
December1st to 10thNight
28%22%32%16%3
760
11th to 20thNight
25%22%33%17%3
760
21st to endNight
26%22%35%15%1
836
Page generated at 2024-01-24 09:37:25. Version ac07

Copyright 2024 Attilla Danko


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