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 2017-03-14.

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%
14845
27%
45203
24%
14809
71%
14809
39%
24710

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
60%
716
19%
2372
19%
716
63%
716
29%
1417
January16th to endNight
60%
768
25%
2496
25%
768
63%
768
27%
1537
February1st to 15thNight
57%
699
24%
2283
23%
699
62%
699
27%
1405
February16th to endNight
51%
632
22%
1895
18%
632
58%
632
28%
1201
March1st to 15thNight
54%
716
19%
1996
17%
716
57%
716
28%
1296
March16th to endNight
53%
704
20%
1914
15%
704
58%
704
30%
1233
April1st to 15thNight
49%
659
22%
1649
12%
659
54%
659
32%
1077
April16th to endNight
58%
660
25%
1650
10%
660
63%
660
46%
935
May1st to 15thNight
67%
577
25%
1567
16%
577
70%
577
51%
821
May16th to endNight
67%
368
23%
1395
20%
368
74%
368
40%
643
June1st to 15thNight
76%
330
28%
1320
28%
330
85%
330
46%
546
June16th to endNight
86%
330
33%
1320
41%
330
90%
330
60%
464
July1st to 15thNight
93%
358
35%
1288
40%
358
94%
358
71%
447
July16th to endNight
88%
522
32%
1467
30%
489
89%
489
60%
653
August1st to 15thNight
85%
518
34%
1501
27%
515
85%
515
58%
690
August16th to endNight
87%
700
34%
1750
21%
700
88%
700
69%
849
September1st to 15thNight
89%
660
42%
1650
31%
660
90%
660
73%
778
September16th to endNight
82%
656
38%
1797
35%
656
84%
656
62%
861
October1st to 15thNight
74%
660
29%
1980
30%
660
78%
660
46%
1017
October16th to endNight
72%
704
32%
2112
33%
704
76%
704
43%
1112
November1st to 15thNight
67%
700
29%
2178
29%
700
71%
700
39%
1181
November16th to endNight
66%
720
26%
2415
27%
720
70%
720
34%
1323
December1st to 15thNight
58%
720
22%
2520
20%
720
65%
720
25%
1523
December16th to endNight
49%
768
19%
2688
17%
768
56%
768
21%
1701

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%
45505
Night
6%42442445%8%55%
45391
TransparencyDay
26%39%20%24%15%
45194
Night
27%410%20%21%15%
45204
SeeingDay
8%10%25%34%17%4
5298
Night
8%412%33%32%8%
14856

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
11%6%2443346%7%45%
1564
16th to endDay
14%6%35%4245%46%44%
1728
February1st to 15thDay
11%7%35%6%3435%6%41%
1581
16th to endDay
14%8%36%6%23346%38%
1579
March1st to 15thDay
9%6%37%5%4445%10%36%
1934
16th to endDay
9%5%26%5%46%5%5%7%40%
1958
April1st to 15thDay
12%6%35%5%2425%7%43%
1969
16th to endDay
6%323322447%58%
1980
May1st to 15thDay
3412212348%63%
2051
16th to endDay
5%414423337%58%
2363
June1st to 15thDay
4412213338%62%
2310
16th to endDay
11112236%78%
2310
July1st to 15thDay
11112235%78%
2254
16th to endDay
111112235%77%
2286
August1st to 15thDay
12112237%75%
2120
16th to endDay
11212247%76%
2100
September1st to 15thDay
11212125%80%
1980
16th to endDay
2212212236%70%
1829
October1st to 15thDay
4323323447%61%
1650
16th to endDay
442332445%6%58%
1760
November1st to 15thDay
6%425%434446%51%
1681
16th to endDay
7%6%25%5%335%46%48%
1542
December1st to 15thDay
10%5%46%6%35%446%40%
1440
16th to endDay
12%8%47%5%2345%6%38%
1536
January1st to 15thNight
9%5%35%5%245%5%7%44%
2372
16th to endNight
12%5%25%5%24447%45%
2496
February1st to 15thNight
8%6%36%6%25%46%7%42%
2271
16th to endNight
13%7%35%43435%8%41%
1895
March1st to 15thNight
10%6%36%5%34447%42%
1996
16th to endNight
8%6%35%4245%47%46%
1914
April1st to 15thNight
10%6%245%25%47%7%44%
1649
16th to endNight
5%22332445%8%58%
1650
May1st to 15thNight
1213323349%62%
1567
16th to endNight
231441335%10%59%
1394
June1st to 15thNight
121221235%11%64%
1320
16th to endNight
112236%77%
1320
July1st to 15thNight
1112248%76%
1372
16th to endNight
1131335%10%66%
1575
August1st to 15thNight
1123134410%65%
1510
16th to endNight
1221346%8%69%
1750
September1st to 15thNight
11112238%75%
1650
16th to endNight
222212337%70%
1797
October1st to 15thNight
4213323347%61%
1980
16th to endNight
432443435%6%58%
2112
November1st to 15thNight
5%424324447%55%
2178
16th to endNight
6%4145%34348%52%
2415
December1st to 15thNight
8%6%35%5%2445%7%44%
2520
16th to endNight
13%6%36%434445%42%
2688

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
36%5%11%19%16%10%
1564
16th to endDay
41%5%6%13%19%13%
1728
February1st to 15thDay
42%47%19%20%5%
1581
16th to endDay
45%5%7%22%13%4
1579
March1st to 15thDay
43%5%9%19%14%5%
1934
16th to endDay
43%5%11%19%16%2
1958
April1st to 15thDay
40%411%20%20%2
1969
16th to endDay
26%414%25%22%6%
1980
May1st to 15thDay
20%49%28%29%7%
2051
16th to endDay
27%413%26%21%6%
2367
June1st to 15thDay
21%5%13%22%23%14%
2310
16th to endDay
10%28%18%35%24%
2310
July1st to 15thDay
10%16%13%26%41%
2110
16th to endDay
10%27%14%30%35%
2131
August1st to 15thDay
11%25%16%29%34%
2104
16th to endDay
9%17%20%33%28%
2100
September1st to 15thDay
9%16%17%32%33%
1980
16th to endDay
15%26%23%30%20%
1829
October1st to 15thDay
22%5%8%19%25%17%
1650
16th to endDay
25%410%22%23%13%
1760
November1st to 15thDay
32%49%25%20%7%
1681
16th to endDay
36%410%17%26%5%
1542
December1st to 15thDay
44%311%15%18%5%
1440
16th to endDay
45%312%15%17%5%
1536
January1st to 15thNight
37%411%20%17%9%
2372
16th to endNight
38%5%8%13%17%16%
2496
February1st to 15thNight
39%48%20%18%8%
2283
16th to endNight
39%5%12%24%14%3
1895
March1st to 15thNight
40%412%19%15%7%
1996
16th to endNight
38%5%11%19%18%6%
1914
April1st to 15thNight
36%5%13%23%17%3
1649
16th to endNight
22%5%15%26%21%8%
1650
May1st to 15thNight
19%6%12%21%27%12%
1568
16th to endNight
20%5%16%26%24%6%
1395
June1st to 15thNight
16%5%14%25%19%18%
1320
16th to endNight
10%26%17%29%32%
1320
July1st to 15thNight
8%1417%26%41%
1288
16th to endNight
14%29%20%21%30%
1467
August1st to 15thNight
16%17%21%22%29%
1501
16th to endNight
12%29%17%28%29%
1750
September1st to 15thNight
9%26%16%28%37%
1650
16th to endNight
14%36%19%32%24%
1797
October1st to 15thNight
22%49%21%22%19%
1980
16th to endNight
24%39%21%24%16%
2112
November1st to 15thNight
27%410%25%22%8%
2178
16th to endNight
30%49%22%22%10%
2415
December1st to 15thNight
39%5%9%17%20%8%
2520
16th to endNight
42%5%11%14%17%7%
2688

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
19%13%27%23%14%1
192
16th to endDay
19%7%32%23%13%3
256
February1st to 15thDay
16%13%29%24%13%2
237
16th to endDay
18%15%31%21%11%1
238
March1st to 15thDay
15%20%28%20%12%3
264
16th to endDay
10%16%35%28%8%1
224
April1st to 15thDay
18%22%31%18%8%
209
16th to endDay
8%26%29%27%7%1
210
May1st to 15thDay
8%14%35%29%9%2
228
16th to endDay
8%15%22%31%18%3
266
June1st to 15thDay
5%11%33%35%12%1
255
16th to endDay
1327%42%18%6%
255
July1st to 15thDay
2215%49%24%5%
245
16th to endDay
119%55%24%7%
271
August1st to 15thDay
123%42%25%5%
255
16th to endDay
117%51%20%9%
268
September1st to 15thDay
218%45%22%10%
255
16th to endDay
6%7%17%34%26%7%
255
October1st to 15thDay
6%7%25%37%18%4
255
16th to endDay
9%7%27%35%15%4
272
November1st to 15thDay
10%9%13%26%28%10%
187
16th to endDay
5%14%29%31%16%2
77
December1st to 15thDay
10%21%25%30%13%
60
16th to endDay
10%18%14%28%20%7%
64
January1st to 15thNight
13%411%34%27%8%
720
16th to endNight
15%412%31%25%11%
768
February1st to 15thNight
13%5%14%32%25%7%
704
16th to endNight
17%6%17%32%20%5%
632
March1st to 15thNight
14%7%16%27%28%5%
716
16th to endNight
12%6%18%33%23%4
704
April1st to 15thNight
13%9%20%31%22%3
659
16th to endNight
6%8%21%31%23%8%
660
May1st to 15thNight
2220%35%31%6%
578
16th to endNight
3415%38%32%5%
369
June1st to 15thNight
2213%47%29%4
330
16th to endNight
17%47%39%2
330
July1st to 15thNight
335%52%8%
358
16th to endNight
125%57%14%
522
August1st to 15thNight
15%35%50%7%
518
16th to endNight
6%32%49%10%
700
September1st to 15thNight
15%28%50%13%
660
16th to endNight
318%32%41%12%
656
October1st to 15thNight
6%210%33%35%12%
660
16th to endNight
7%38%29%34%16%
704
November1st to 15thNight
8%114%31%33%10%
700
16th to endNight
8%411%37%29%10%
720
December1st to 15thNight
13%412%35%26%7%
720
16th to endNight
15%8%17%33%21%4
768
Page generated at 2017-03-15 08:32:40. Version ac04

Copyright 2017 A. Danko


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