Saratoga
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Saratoga clear sky chart from 2005-11-05 to 2018-03-21.

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
67%
16175
27%
49246
24%
16139
71%
16139
39%
26802

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 15thNight
59%
776
19%
2571
19%
776
62%
776
27%
1569
January16th to endNight
60%
832
24%
2704
24%
832
63%
832
27%
1676
February1st to 15thNight
59%
759
26%
2477
26%
759
65%
759
29%
1477
February16th to endNight
52%
684
24%
2051
19%
684
60%
684
29%
1277
March1st to 15thNight
53%
780
19%
2174
17%
780
56%
780
28%
1428
March16th to endNight
52%
792
20%
2154
15%
792
57%
792
30%
1394
April1st to 15thNight
50%
719
22%
1799
12%
719
54%
719
32%
1176
April16th to endNight
58%
720
26%
1800
11%
720
63%
720
44%
1032
May1st to 15thNight
67%
629
24%
1709
15%
629
70%
629
51%
895
May16th to endNight
68%
402
25%
1525
23%
402
74%
402
40%
702
June1st to 15thNight
75%
360
26%
1440
27%
360
83%
360
46%
593
June16th to endNight
87%
360
35%
1440
44%
360
90%
360
61%
501
July1st to 15thNight
93%
393
33%
1413
38%
393
95%
393
73%
483
July16th to endNight
89%
564
34%
1593
32%
531
89%
531
61%
702
August1st to 15thNight
85%
565
32%
1638
25%
562
86%
562
58%
753
August16th to endNight
87%
764
37%
1910
24%
764
89%
764
70%
917
September1st to 15thNight
89%
720
40%
1800
29%
720
89%
720
71%
858
September16th to endNight
82%
716
41%
1961
37%
716
84%
716
64%
923
October1st to 15thNight
75%
720
29%
2160
30%
720
79%
720
49%
1077
October16th to endNight
74%
768
34%
2304
36%
768
77%
768
45%
1192
November1st to 15thNight
68%
760
28%
2365
28%
760
72%
760
39%
1294
November16th to endNight
66%
780
26%
2616
28%
780
69%
780
33%
1452
December1st to 15thNight
60%
780
24%
2730
22%
780
66%
780
27%
1598
December16th to endNight
50%
832
21%
2912
18%
832
57%
832
21%
1833

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
6%423323347%58%
49601
Night
6%42442445%7%55%
49434
TransparencyDay
26%39%20%24%16%
49290
Night
27%410%20%21%15%
49247
SeeingDay
8%10%24%33%18%5%
6639
Night
8%412%33%33%8%
16186

By Month

Percentage Cloud Cover SW (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 15thDay
12%6%244345%5%8%42%
1695
16th to endDay
13%6%244245%47%43%
1872
February1st to 15thDay
10%7%346%3445%6%43%
1717
16th to endDay
13%7%36%6%24346%40%
1709
March1st to 15thDay
10%6%37%5%45%46%10%35%
2115
16th to endDay
10%6%26%6%45%5%5%7%39%
2197
April1st to 15thDay
12%6%35%5%2435%7%43%
2149
16th to endDay
7%423322447%57%
2160
May1st to 15thDay
3312212348%64%
2238
16th to endDay
5%414423337%59%
2584
June1st to 15thDay
4412213338%63%
2520
16th to endDay
11112236%79%
2520
July1st to 15thDay
11112235%79%
2459
16th to endDay
111112235%78%
2468
August1st to 15thDay
112212237%74%
2313
16th to endDay
1112246%77%
2292
September1st to 15thDay
11212135%78%
2160
16th to endDay
3212212246%70%
1995
October1st to 15thDay
3323323447%63%
1800
16th to endDay
442232445%6%59%
1920
November1st to 15thDay
6%425%4245%47%50%
1824
16th to endDay
7%5%25%5%335%47%47%
1670
December1st to 15thDay
10%5%46%6%35%446%42%
1560
16th to endDay
11%8%47%42345%7%38%
1664
January1st to 15thNight
10%6%35%5%345%6%8%41%
2571
16th to endNight
12%5%25%5%24447%44%
2704
February1st to 15thNight
7%5%36%5%25%45%7%45%
2465
16th to endNight
12%7%25%33435%8%43%
2051
March1st to 15thNight
10%6%36%5%345%5%7%41%
2174
16th to endNight
9%6%35%5%245%47%45%
2154
April1st to 15thNight
10%5%24425%47%7%45%
1799
16th to endNight
5%22332445%8%58%
1800
May1st to 15thNight
1213323349%63%
1709
16th to endNight
231441335%10%59%
1524
June1st to 15thNight
121221235%10%65%
1440
16th to endNight
1112236%78%
1440
July1st to 15thNight
112247%78%
1497
16th to endNight
1131335%9%68%
1701
August1st to 15thNight
1123143410%65%
1647
16th to endNight
1121335%8%70%
1910
September1st to 15thNight
11112338%74%
1800
16th to endNight
222212237%72%
1961
October1st to 15thNight
3213323347%64%
2160
16th to endNight
431342435%6%59%
2304
November1st to 15thNight
5%42432445%7%54%
2365
16th to endNight
6%5%245%34348%51%
2616
December1st to 15thNight
8%6%35%5%2445%8%46%
2730
16th to endNight
12%6%36%434446%42%
2912

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 15thDay
38%5%11%19%15%9%
1695
16th to endDay
40%5%7%14%19%12%
1872
February1st to 15thDay
39%47%19%21%7%
1717
16th to endDay
44%5%8%22%15%4
1709
March1st to 15thDay
44%5%10%20%14%5%
2115
16th to endDay
44%5%12%18%16%2
2197
April1st to 15thDay
40%411%21%19%2
2149
16th to endDay
27%413%25%22%7%
2160
May1st to 15thDay
19%49%30%29%7%
2238
16th to endDay
26%413%25%23%6%
2588
June1st to 15thDay
21%412%22%24%13%
2520
16th to endDay
10%27%17%34%27%
2520
July1st to 15thDay
9%15%12%24%45%
2315
16th to endDay
9%26%13%28%39%
2313
August1st to 15thDay
12%25%16%30%33%
2297
16th to endDay
8%16%20%32%29%
2292
September1st to 15thDay
10%16%17%31%31%
2160
16th to endDay
15%26%24%31%18%
1995
October1st to 15thDay
21%47%18%24%22%
1800
16th to endDay
24%410%21%23%15%
1920
November1st to 15thDay
31%5%10%25%20%6%
1824
16th to endDay
35%410%18%26%5%
1670
December1st to 15thDay
42%311%14%18%10%
1560
16th to endDay
44%411%15%18%5%
1664
January1st to 15thNight
38%5%11%19%16%8%
2571
16th to endNight
39%5%9%14%16%15%
2704
February1st to 15thNight
37%48%19%21%9%
2477
16th to endNight
37%5%12%25%15%3
2051
March1st to 15thNight
41%411%20%15%6%
2174
16th to endNight
39%5%12%19%17%5%
2154
April1st to 15thNight
36%5%13%23%17%3
1799
16th to endNight
23%5%14%26%20%9%
1800
May1st to 15thNight
19%5%12%22%28%11%
1710
16th to endNight
20%5%16%26%24%6%
1525
June1st to 15thNight
16%413%25%22%17%
1440
16th to endNight
10%26%16%30%33%
1440
July1st to 15thNight
7%1415%24%45%
1413
16th to endNight
14%28%19%20%34%
1593
August1st to 15thNight
17%27%20%22%30%
1638
16th to endNight
11%19%16%29%30%
1910
September1st to 15thNight
10%27%16%27%35%
1800
16th to endNight
13%26%20%33%23%
1961
October1st to 15thNight
21%39%19%22%24%
2160
16th to endNight
23%39%20%24%18%
2304
November1st to 15thNight
28%411%25%21%7%
2365
16th to endNight
32%49%22%22%9%
2616
December1st to 15thNight
36%49%16%19%12%
2730
16th to endNight
42%5%11%14%19%7%
2912

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 15thDay
22%11%24%24%15%1
233
16th to endDay
16%7%30%24%16%3
304
February1st to 15thDay
13%12%28%25%14%4
283
16th to endDay
16%17%31%20%12%2
290
March1st to 15thDay
16%18%27%21%13%2
330
16th to endDay
13%16%31%27%8%1
311
April1st to 15thDay
17%21%30%18%10%1
269
16th to endDay
9%25%30%24%8%1
270
May1st to 15thDay
7%16%32%30%10%2
288
16th to endDay
7%13%21%32%19%5%
330
June1st to 15thDay
5%12%32%33%12%4
315
16th to endDay
323%43%20%7%
315
July1st to 15thDay
2112%47%28%6%
305
16th to endDay
111%50%25%10%
327
August1st to 15thDay
120%39%30%7%
315
16th to endDay
115%45%24%13%
332
September1st to 15thDay
317%44%23%10%
315
16th to endDay
6%7%18%34%25%7%
315
October1st to 15thDay
5%8%26%35%18%5%
315
16th to endDay
8%6%23%33%19%8%
336
November1st to 15thDay
10%7%17%28%25%10%
240
16th to endDay
6%9%26%32%21%2
115
December1st to 15thDay
6%17%18%25%23%7%
90
16th to endDay
10%16%14%23%21%12%
96
January1st to 15thNight
14%411%33%28%7%
780
16th to endNight
15%412%31%26%10%
832
February1st to 15thNight
12%5%13%33%26%7%
764
16th to endNight
16%6%17%33%21%4
684
March1st to 15thNight
14%7%16%28%28%5%
780
16th to endNight
13%6%19%33%23%3
792
April1st to 15thNight
13%9%20%31%21%3
719
16th to endNight
6%8%21%32%22%7%
720
May1st to 15thNight
2320%36%31%6%
630
16th to endNight
3414%38%32%5%
403
June1st to 15thNight
2213%45%31%3
360
16th to endNight
117%46%40%2
360
July1st to 15thNight
332%55%7%
393
16th to endNight
126%55%15%
564
August1st to 15thNight
15%33%51%7%
565
16th to endNight
5%31%50%10%
764
September1st to 15thNight
15%31%48%13%
720
16th to endNight
218%33%40%12%
716
October1st to 15thNight
5%210%35%34%11%
720
16th to endNight
7%28%27%36%17%
768
November1st to 15thNight
8%113%33%33%9%
760
16th to endNight
8%411%37%29%9%
780
December1st to 15thNight
12%412%35%27%7%
780
16th to endNight
15%7%16%32%22%4
832
Page generated at 2018-03-22 08:34:23. Version ac04

Copyright 2018 A. Danko


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