This page made possible by the sponsorship of: David & Wendee Levy
(Jarnac Observatory).

Adirondack Astronomy Retreat
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Adirondack Astronomy Retreat clear sky chart from 2005-11-05 to 2017-09-10.

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
26%
14704
13%
46770
7%
14673
33%
14673
14%
33137

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
14%
720
9%
2506
3%
716
21%
716
8%
1934
January16th to endNight
15%
768
12%
2688
4%
768
26%
768
10%
1928
February1st to 15thNight
12%
704
9%
2268
2%
701
20%
701
8%
1760
February16th to endNight
18%
631
13%
1893
5%
631
28%
631
11%
1411
March1st to 15thNight
17%
720
13%
2160
6%
720
25%
720
11%
1613
March16th to endNight
19%
768
18%
1998
5%
768
29%
768
15%
1436
April1st to 15thNight
18%
718
14%
1796
4%
718
24%
718
15%
1342
April16th to endNight
23%
633
16%
1713
4%
633
31%
633
16%
1205
May1st to 15thNight
22%
435
15%
1515
8%
435
33%
435
13%
1037
May16th to endNight
30%
374
12%
1497
9%
374
41%
374
15%
965
June1st to 15thNight
29%
360
10%
1440
6%
360
41%
360
13%
984
June16th to endNight
40%
360
10%
1440
10%
360
49%
360
18%
882
July1st to 15thNight
44%
340
11%
1360
13%
340
51%
340
21%
781
July16th to endNight
45%
376
14%
1418
14%
354
55%
354
23%
810
August1st to 15thNight
49%
404
15%
1475
13%
402
54%
402
21%
881
August16th to endNight
52%
764
19%
1910
10%
764
55%
764
34%
1209
September1st to 15thNight
44%
700
15%
1750
7%
700
46%
700
28%
1191
September16th to endNight
42%
657
21%
1815
13%
657
47%
657
30%
1130
October1st to 15thNight
30%
660
17%
1928
10%
660
38%
660
17%
1348
October16th to endNight
23%
704
10%
2252
4%
704
31%
704
12%
1711
November1st to 15thNight
23%
700
14%
2277
9%
700
30%
700
13%
1647
November16th to endNight
20%
720
14%
2463
7%
720
29%
720
10%
1787
December1st to 15thNight
13%
720
6%
2520
1%
720
18%
720
6%
1977
December16th to endNight
10%
768
8%
2688
2%
768
18%
768
6%
2168

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%8%36%6%35%5%5%7%33%
47868
Night
14%8%37%6%35%45%6%34%
46940
Cloud CoverDay
13%8%37%6%35%5%5%7%32%
47878
Night
14%8%37%6%35%45%6%34%
46945
TransparencyDay
49%9%12%17%9%1
47556
Night
48%8%12%18%9%1
46770
SeeingDay
18%23%27%18%8%3
5625
Night
16%27%25%20%8%
14705

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 15thDay
12%11%5%10%8%45%6%46%23%
1432
16th to endDay
8%10%49%8%5%7%45%6%29%
1536
February1st to 15thDay
10%12%5%8%9%46%5%7%5%24%
1591
16th to endDay
12%9%6%11%7%3445%430%
1580
March1st to 15thDay
13%11%5%8%6%45%5%6%427%
1790
16th to endDay
12%10%46%5%35%445%37%
2224
April1st to 15thDay
17%9%35%5%24346%35%
2152
16th to endDay
16%8%26%6%24446%37%
2247
May1st to 15thDay
18%8%37%5%3445%6%33%
2445
16th to endDay
15%6%25%6%45%5%6%7%33%
2618
June1st to 15thDay
20%6%35%6%35%5%5%7%29%
2520
16th to endDay
16%5%26%6%45%5%6%9%31%
2520
July1st to 15thDay
10%6%25%6%47%6%6%10%33%
2520
16th to endDay
11%426%6%46%6%6%9%35%
2654
August1st to 15thDay
10%5%25%7%46%6%7%9%33%
2461
16th to endDay
9%425%5%45%5%6%8%41%
2292
September1st to 15thDay
13%7%2343445%7%43%
2098
16th to endDay
10%4244345%6%7%47%
1815
October1st to 15thDay
19%8%26%5%345%5%6%32%
1702
16th to endDay
18%9%46%6%25%5%5%6%28%
1620
November1st to 15thDay
14%11%25%6%4445%6%34%
1581
16th to endDay
14%9%46%5%35%5%5%6%33%
1494
December1st to 15thDay
17%16%5%7%6%45%446%22%
1440
16th to endDay
19%17%6%9%433445%20%
1536
January1st to 15thNight
12%10%410%7%46%5%5%6%23%
2506
16th to endNight
9%11%5%9%7%45%45%7%30%
2688
February1st to 15thNight
9%11%6%11%8%37%6%6%5%23%
2267
16th to endNight
11%8%5%10%7%35%45%5%31%
1893
March1st to 15thNight
16%10%48%6%3434432%
2147
16th to endNight
13%8%47%5%34345%39%
1998
April1st to 15thNight
16%8%37%6%45%446%32%
1796
16th to endNight
18%6%25%6%24446%39%
1713
May1st to 15thNight
18%6%25%6%34446%35%
1515
16th to endNight
14%5%35%5%245%6%8%38%
1495
June1st to 15thNight
21%5%25%5%345%47%34%
1440
16th to endNight
14%315%436%5%5%9%40%
1440
July1st to 15thNight
10%4244335%6%9%44%
1440
16th to endNight
10%4145%2446%9%46%
1514
August1st to 15thNight
9%315%5%35%6%6%8%44%
1485
16th to endNight
9%4243345%6%8%49%
1910
September1st to 15thNight
14%4245%34447%45%
1750
16th to endNight
14%31342335%7%49%
1815
October1st to 15thNight
18%7%25%5%3445%6%37%
1928
16th to endNight
21%9%26%6%35%445%29%
2252
November1st to 15thNight
16%9%36%5%25%45%5%33%
2277
16th to endNight
16%8%47%5%35%445%33%
2463
December1st to 15thNight
18%13%5%7%6%45%445%23%
2520
16th to endNight
18%15%6%9%7%3434422%
2688

Percentage Cloud Cover SE (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%11%5%9%9%5%5%6%5%6%21%
1432
16th to endDay
8%9%310%8%5%7%45%7%28%
1536
February1st to 15thDay
9%11%6%7%9%6%6%5%5%6%24%
1591
16th to endDay
12%9%6%11%8%3345%5%29%
1580
March1st to 15thDay
14%11%5%8%7%46%5%5%5%26%
1800
16th to endDay
12%9%47%5%4444437%
2224
April1st to 15thDay
16%9%46%5%24446%35%
2152
16th to endDay
15%8%37%5%24446%36%
2247
May1st to 15thDay
17%7%46%5%3445%6%33%
2445
16th to endDay
14%7%35%6%35%5%6%8%33%
2618
June1st to 15thDay
19%6%46%5%45%5%5%7%29%
2520
16th to endDay
14%5%26%6%46%6%6%9%30%
2520
July1st to 15thDay
9%6%26%5%47%6%7%10%34%
2520
16th to endDay
10%436%6%36%6%7%9%34%
2654
August1st to 15thDay
8%6%26%6%46%6%8%9%33%
2461
16th to endDay
8%425%6%35%5%6%9%41%
2292
September1st to 15thDay
13%6%25%43445%7%42%
2098
16th to endDay
10%4244245%6%7%46%
1815
October1st to 15thDay
18%8%26%6%3446%6%32%
1702
16th to endDay
16%10%47%6%346%5%6%28%
1620
November1st to 15thDay
13%9%37%6%35%45%6%33%
1581
16th to endDay
14%9%46%6%45%46%5%33%
1494
December1st to 15thDay
16%16%5%8%6%35%45%7%21%
1440
16th to endDay
18%18%6%9%43445%5%19%
1536
January1st to 15thNight
12%11%5%10%8%46%5%6%7%22%
2506
16th to endNight
9%11%5%10%7%45%5%5%6%30%
2688
February1st to 15thNight
8%11%6%11%8%36%6%6%6%22%
2260
16th to endNight
11%8%412%7%35%45%5%30%
1893
March1st to 15thNight
15%10%48%7%35%34431%
2160
16th to endNight
12%9%38%5%34346%38%
1997
April1st to 15thNight
15%9%36%6%35%45%6%32%
1796
16th to endNight
17%7%25%5%2435%6%39%
1713
May1st to 15thNight
17%8%25%6%34447%34%
1515
16th to endNight
13%6%26%5%345%5%8%37%
1495
June1st to 15thNight
20%6%345%2446%7%34%
1440
16th to endNight
13%414446%5%5%9%40%
1440
July1st to 15thNight
9%4245%245%7%10%43%
1440
16th to endNight
10%4145%25%46%9%45%
1514
August1st to 15thNight
8%325%6%36%5%6%8%44%
1485
16th to endNight
8%414335%5%6%8%48%
1910
September1st to 15thNight
14%4245%3435%6%45%
1750
16th to endNight
12%4235%2335%7%49%
1815
October1st to 15thNight
16%8%35%5%3445%6%36%
1928
16th to endNight
20%10%36%6%35%5%45%29%
2252
November1st to 15thNight
16%9%36%6%35%445%33%
2277
16th to endNight
16%8%48%5%35%446%32%
2463
December1st to 15thNight
17%13%5%8%7%45%45%5%22%
2520
16th to endNight
17%15%6%9%7%4444421%
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
59%9%10%14%5%
1433
16th to endDay
52%8%14%13%9%
1536
February1st to 15thDay
58%10%10%14%5%
1594
16th to endDay
55%7%12%11%11%1
1580
March1st to 15thDay
57%8%12%12%7%1
1800
16th to endDay
49%6%10%16%14%3
2224
April1st to 15thDay
49%7%10%18%11%2
2152
16th to endDay
48%7%9%18%12%3
2247
May1st to 15thDay
51%6%9%17%12%1
2445
16th to endDay
47%9%13%16%12%1
2622
June1st to 15thDay
53%8%12%16%8%
2520
16th to endDay
47%10%14%17%9%
2520
July1st to 15thDay
43%9%15%22%8%
2371
16th to endDay
43%11%16%19%8%
2487
August1st to 15thDay
43%12%16%19%8%
2447
16th to endDay
38%9%16%24%11%
2292
September1st to 15thDay
40%8%11%27%11%
2098
16th to endDay
35%8%15%25%14%1
1815
October1st to 15thDay
50%8%12%19%8%
1702
16th to endDay
54%9%13%16%5%
1620
November1st to 15thDay
49%7%14%17%9%1
1581
16th to endDay
50%9%11%18%8%1
1494
December1st to 15thDay
62%8%11%12%4
1440
16th to endDay
66%8%9%8%6%
1536
January1st to 15thNight
56%11%11%13%6%
2506
16th to endNight
51%9%11%16%10%1
2688
February1st to 15thNight
57%9%12%12%7%
2268
16th to endNight
53%8%10%16%9%
1893
March1st to 15thNight
55%6%9%18%8%1
2160
16th to endNight
47%6%10%17%14%3
1998
April1st to 15thNight
50%7%10%18%12%1
1796
16th to endNight
45%8%10%19%13%2
1713
May1st to 15thNight
48%7%8%16%17%2
1515
16th to endNight
43%8%14%19%11%1
1497
June1st to 15thNight
48%8%13%19%8%
1440
16th to endNight
37%9%16%24%10%
1440
July1st to 15thNight
33%10%17%26%11%
1360
16th to endNight
32%9%18%25%12%1
1418
August1st to 15thNight
34%10%18%24%11%
1475
16th to endNight
31%7%17%30%12%
1910
September1st to 15thNight
38%8%14%27%10%
1750
16th to endNight
33%7%14%29%14%1
1815
October1st to 15thNight
46%7%12%20%11%
1928
16th to endNight
55%9%12%15%6%
2252
November1st to 15thNight
51%8%12%14%10%2
2277
16th to endNight
52%9%12%18%6%1
2463
December1st to 15thNight
61%8%12%13%3
2520
16th to endNight
64%8%9%12%4
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
13%38%21%11%13%1
60
16th to endDay
23%26%34%10%4
64
February1st to 15thDay
29%30%31%6%2
116
16th to endDay
20%30%29%15%3
239
March1st to 15thDay
22%30%24%20%2
270
16th to endDay
18%35%22%14%6%2
288
April1st to 15thDay
22%30%26%14%5%1
270
16th to endDay
21%32%21%13%7%3
270
May1st to 15thDay
27%25%24%13%6%3
288
16th to endDay
17%26%31%17%5%1
331
June1st to 15thDay
23%25%31%14%5%
315
16th to endDay
14%22%36%18%5%1
315
July1st to 15thDay
13%17%30%21%15%1
305
16th to endDay
10%16%34%26%9%2
326
August1st to 15thDay
10%14%32%23%14%5%
313
16th to endDay
11%15%20%24%16%11%
332
September1st to 15thDay
15%13%25%22%13%9%
294
16th to endDay
11%16%27%17%13%12%
254
October1st to 15thDay
20%21%21%20%14%2
255
16th to endDay
23%23%27%20%4
247
November1st to 15thDay
18%20%27%22%9%1
235
16th to endDay
19%31%24%14%7%2
114
December1st to 15thDay
13%31%38%8%6%1
60
16th to endDay
37%26%29%41
64
January1st to 15thNight
12%33%33%16%3
720
16th to endNight
13%35%31%16%3
768
February1st to 15thNight
13%31%36%16%2
704
16th to endNight
15%35%25%19%3
631
March1st to 15thNight
20%33%26%17%2
720
16th to endNight
16%35%25%16%5%
768
April1st to 15thNight
17%34%25%18%3
718
16th to endNight
17%31%24%18%6%
633
May1st to 15thNight
19%27%26%18%8%
435
16th to endNight
13%25%28%22%9%
375
June1st to 15thNight
19%24%24%21%10%
360
16th to endNight
12%19%24%32%10%1
360
July1st to 15thNight
9%14%25%30%18%2
340
16th to endNight
9%19%21%34%15%
376
August1st to 15thNight
11%11%21%36%18%1
404
16th to endNight
10%13%19%32%22%2
764
September1st to 15thNight
14%15%22%30%15%2
700
16th to endNight
12%17%24%23%18%3
657
October1st to 15thNight
20%22%21%23%11%
660
16th to endNight
23%24%24%20%5%
704
November1st to 15thNight
17%27%28%18%7%1
700
16th to endNight
17%36%22%13%9%
720
December1st to 15thNight
21%35%25%13%4
720
16th to endNight
22%33%27%13%3
768
Page generated at 2017-09-11 19:35:26. Version ac04

Copyright 2017 A. Danko


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