SUNY Ulster
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the SUNY Ulster clear sky chart from 2005-11-05 to 2017-10-06.

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
38%
15009
18%
47064
11%
14978
46%
14978
23%
30658

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
28%
720
18%
2506
8%
716
41%
716
19%
1592
January16th to endNight
27%
768
19%
2618
9%
768
41%
768
20%
1676
February1st to 15thNight
22%
704
15%
2246
4%
701
35%
701
17%
1525
February16th to endNight
24%
631
23%
1893
9%
631
40%
631
22%
1234
March1st to 15thNight
27%
720
17%
2154
8%
720
37%
720
21%
1454
March16th to endNight
28%
768
22%
1994
9%
768
38%
768
24%
1355
April1st to 15thNight
25%
718
16%
1796
5%
718
31%
718
21%
1301
April16th to endNight
32%
690
16%
1770
5%
690
39%
690
26%
1225
May1st to 15thNight
33%
471
18%
1551
11%
471
41%
471
20%
1031
May16th to endNight
46%
374
15%
1497
14%
374
52%
374
20%
928
June1st to 15thNight
47%
360
13%
1440
13%
360
56%
360
18%
915
June16th to endNight
61%
360
14%
1440
17%
360
66%
360
28%
803
July1st to 15thNight
61%
340
13%
1360
18%
340
63%
340
23%
793
July16th to endNight
62%
376
15%
1418
18%
354
67%
354
24%
822
August1st to 15thNight
62%
512
17%
1583
14%
510
64%
510
31%
968
August16th to endNight
62%
764
19%
1910
12%
764
64%
764
33%
1280
September1st to 15thNight
52%
720
22%
1800
12%
720
55%
720
33%
1188
September16th to endNight
56%
717
27%
1968
20%
717
61%
717
36%
1191
October1st to 15thNight
45%
684
21%
2006
17%
684
51%
684
26%
1301
October16th to endNight
32%
704
17%
2208
9%
704
42%
704
21%
1485
November1st to 15thNight
36%
700
20%
2277
12%
700
47%
700
22%
1466
November16th to endNight
33%
720
18%
2421
13%
720
42%
720
19%
1585
December1st to 15thNight
28%
720
15%
2520
8%
720
38%
720
17%
1706
December16th to endNight
24%
768
15%
2688
6%
768
36%
768
16%
1834

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%6%25%5%35%5%5%7%39%
48147
Night
15%6%2442445%6%42%
47234
Cloud CoverDay
15%6%25%5%35%45%7%39%
48156
Night
15%6%25%42445%6%41%
47240
TransparencyDay
43%7%13%20%13%1
47835
Night
42%6%13%22%14%1
47064
SeeingDay
18%9%24%26%14%5%
5806
Night
19%9%28%31%11%1
15010

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%7%35%5%345%6%6%38%
1432
16th to endDay
11%6%25%6%345%5%7%39%
1605
February1st to 15thDay
12%7%37%6%45%45%6%34%
1615
16th to endDay
14%7%35%5%345%45%39%
1580
March1st to 15thDay
15%7%46%4345%5%6%36%
1796
16th to endDay
14%7%36%433336%42%
2229
April1st to 15thDay
17%7%35%43435%5%39%
2152
16th to endDay
17%4245%2435%5%43%
2190
May1st to 15thDay
20%6%25%5%3445%6%34%
2411
16th to endDay
15%5%25%5%25%6%6%8%36%
2618
June1st to 15thDay
19%4245%35%5%6%7%34%
2520
16th to endDay
12%5%25%6%45%6%7%9%35%
2520
July1st to 15thDay
9%5%25%5%47%6%7%8%36%
2520
16th to endDay
10%425%6%36%6%7%9%37%
2654
August1st to 15thDay
12%5%25%5%36%5%7%9%37%
2353
16th to endDay
11%4245%25%5%7%7%43%
2292
September1st to 15thDay
14%425%5%2435%6%44%
2160
16th to endDay
13%41342445%7%49%
1992
October1st to 15thDay
17%6%24424445%43%
1750
16th to endDay
18%5%25%5%25%5%5%6%37%
1664
November1st to 15thDay
15%7%24424345%45%
1581
16th to endDay
17%7%23424346%41%
1537
December1st to 15thDay
16%6%37%6%35%5%45%35%
1440
16th to endDay
18%7%35%5%3445%6%35%
1536
January1st to 15thNight
15%5%35%33446%6%40%
2506
16th to endNight
12%8%35%5%345%5%6%40%
2618
February1st to 15thNight
12%8%46%4345%5%6%37%
2245
16th to endNight
13%8%25%434436%43%
1893
March1st to 15thNight
16%6%25%5%24446%41%
2141
16th to endNight
13%7%35%424445%44%
1994
April1st to 15thNight
17%7%26%5%3445%6%36%
1796
16th to endNight
18%42443345%6%42%
1770
May1st to 15thNight
18%6%34433447%38%
1551
16th to endNight
14%5%15%4245%5%7%40%
1495
June1st to 15thNight
20%42342445%7%40%
1440
16th to endNight
12%31332446%10%47%
1440
July1st to 15thNight
11%423435%47%8%44%
1440
16th to endNight
10%324435%6%5%9%44%
1514
August1st to 15thNight
10%4234145%5%8%47%
1593
16th to endNight
13%31443445%7%46%
1910
September1st to 15thNight
14%423424346%49%
1800
16th to endNight
11%423423436%53%
1968
October1st to 15thNight
18%5%24424335%45%
2006
16th to endNight
20%5%25%423445%40%
2208
November1st to 15thNight
15%7%34424445%44%
2277
16th to endNight
17%6%245%2445%6%39%
2421
December1st to 15thNight
19%6%25%424446%37%
2520
16th to endNight
18%8%35%434447%35%
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
13%6%25%5%35%6%6%6%37%
1432
16th to endDay
11%7%26%6%3445%8%38%
1605
February1st to 15thDay
13%8%37%7%25%5%5%6%33%
1615
16th to endDay
14%8%25%5%45%446%38%
1580
March1st to 15thDay
16%8%36%5%25%5%46%35%
1806
16th to endDay
15%7%36%5%24335%42%
2228
April1st to 15thDay
17%7%35%43435%5%38%
2152
16th to endDay
16%415%5%24346%43%
2190
May1st to 15thDay
20%6%35%6%34346%34%
2411
16th to endDay
15%5%26%425%5%6%7%36%
2618
June1st to 15thDay
20%425%435%46%8%34%
2520
16th to endDay
12%5%25%6%35%6%7%10%35%
2520
July1st to 15thDay
10%5%246%46%6%7%9%36%
2520
16th to endDay
10%325%5%36%6%7%9%37%
2654
August1st to 15thDay
12%5%25%5%35%6%6%9%38%
2353
16th to endDay
11%4245%3446%8%44%
2292
September1st to 15thDay
14%6%145%3445%6%43%
2160
16th to endDay
13%41342445%6%49%
1992
October1st to 15thDay
17%6%2433445%5%42%
1750
16th to endDay
18%5%25%435%446%37%
1664
November1st to 15thDay
16%6%24424345%45%
1581
16th to endDay
18%6%33414436%41%
1537
December1st to 15thDay
16%7%37%5%345%45%35%
1440
16th to endDay
19%8%345%2445%6%34%
1536
January1st to 15thNight
15%5%35%43445%6%39%
2506
16th to endNight
12%8%35%5%245%6%7%39%
2618
February1st to 15thNight
13%8%36%436%446%37%
2238
16th to endNight
13%7%35%434345%42%
1893
March1st to 15thNight
16%8%245%24346%39%
2154
16th to endNight
14%8%34424445%43%
1994
April1st to 15thNight
17%8%26%6%3345%6%35%
1796
16th to endNight
18%5%24424346%43%
1770
May1st to 15thNight
18%6%35%4245%36%39%
1551
16th to endNight
15%5%25%4345%5%7%40%
1495
June1st to 15thNight
20%424325%35%8%38%
1440
16th to endNight
12%313425%46%10%46%
1440
July1st to 15thNight
11%5%25%5%25%5%6%9%43%
1440
16th to endNight
10%4145%35%5%7%8%42%
1514
August1st to 15thNight
10%4245%2347%9%45%
1593
16th to endNight
13%414425%5%5%7%44%
1910
September1st to 15thNight
14%5%24324347%47%
1800
16th to endNight
11%42342335%6%52%
1968
October1st to 15thNight
17%6%15%422345%45%
2006
16th to endNight
20%6%25%423445%40%
2208
November1st to 15thNight
14%8%35%423335%43%
2277
16th to endNight
18%6%25%5%2445%6%38%
2421
December1st to 15thNight
20%7%25%5%24446%36%
2520
16th to endNight
19%8%35%424447%34%
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
42%6%16%21%10%1
1433
16th to endDay
43%6%14%23%11%2
1605
February1st to 15thDay
48%7%12%18%11%1
1618
16th to endDay
45%5%11%22%12%1
1580
March1st to 15thDay
47%6%14%19%10%1
1806
16th to endDay
45%5%9%18%17%3
2229
April1st to 15thDay
46%5%10%21%13%3
2152
16th to endDay
42%5%8%22%17%3
2190
May1st to 15thDay
49%6%9%19%12%2
2411
16th to endDay
43%9%14%19%12%1
2622
June1st to 15thDay
46%8%15%18%10%
2520
16th to endDay
42%10%13%22%10%1
2520
July1st to 15thDay
42%9%12%19%14%1
2371
16th to endDay
39%9%16%19%13%1
2487
August1st to 15thDay
39%10%15%21%12%
2339
16th to endDay
35%8%14%24%16%
2292
September1st to 15thDay
40%6%11%20%18%1
2160
16th to endDay
33%6%11%23%22%2
1992
October1st to 15thDay
42%6%11%22%14%2
1750
16th to endDay
46%5%13%20%11%1
1664
November1st to 15thDay
41%5%14%20%15%2
1581
16th to endDay
43%411%25%12%1
1537
December1st to 15thDay
49%7%15%19%8%1
1440
16th to endDay
49%6%15%18%9%
1536
January1st to 15thNight
43%5%15%20%12%2
2506
16th to endNight
42%6%12%24%12%2
2618
February1st to 15thNight
46%7%14%18%10%2
2246
16th to endNight
41%5%12%22%15%2
1893
March1st to 15thNight
44%5%14%20%12%2
2154
16th to endNight
42%5%10%20%17%3
1994
April1st to 15thNight
47%6%10%19%13%1
1796
16th to endNight
42%6%9%19%19%2
1770
May1st to 15thNight
45%6%10%19%16%2
1551
16th to endNight
41%7%16%20%12%1
1497
June1st to 15thNight
43%7%14%21%11%1
1440
16th to endNight
32%7%17%29%11%1
1440
July1st to 15thNight
36%7%14%26%13%2
1360
16th to endNight
35%8%15%23%13%3
1418
August1st to 15thNight
33%8%15%25%15%1
1583
16th to endNight
36%8%11%25%17%
1910
September1st to 15thNight
36%6%12%24%18%
1800
16th to endNight
32%5%10%23%26%1
1968
October1st to 15thNight
41%5%10%21%18%1
2006
16th to endNight
45%5%13%23%12%
2208
November1st to 15thNight
42%5%12%19%15%3
2277
16th to endNight
45%5%14%22%10%1
2421
December1st to 15thNight
47%6%15%20%10%
2520
16th to endNight
49%5%15%18%10%
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
20%18%30%23%8%
60
16th to endDay
21%18%38%18%2
75
February1st to 15thDay
19%27%33%16%1
131
16th to endDay
19%15%33%27%4
239
March1st to 15thDay
23%15%27%25%7%
270
16th to endDay
19%13%30%26%6%3
288
April1st to 15thDay
24%12%30%18%11%2
270
16th to endDay
20%11%30%19%10%7%
270
May1st to 15thDay
31%11%22%22%9%2
288
16th to endDay
19%8%24%25%17%3
331
June1st to 15thDay
24%9%22%27%14%2
315
16th to endDay
16%9%27%26%18%1
315
July1st to 15thDay
13%227%33%18%4
305
16th to endDay
12%323%33%20%7%
326
August1st to 15thDay
14%317%33%19%11%
313
16th to endDay
12%315%28%26%13%
332
September1st to 15thDay
16%9%17%25%20%10%
315
16th to endDay
14%421%21%21%17%
314
October1st to 15thDay
21%416%27%24%6%
278
16th to endDay
18%12%28%30%10%
255
November1st to 15thDay
20%9%20%32%13%2
235
16th to endDay
19%12%29%28%7%3
157
December1st to 15thDay
15%23%30%21%10%
60
16th to endDay
28%14%42%15%
64
January1st to 15thNight
18%12%34%29%4
720
16th to endNight
18%11%36%31%2
768
February1st to 15thNight
17%14%38%28%1
704
16th to endNight
18%16%35%25%3
631
March1st to 15thNight
22%13%33%27%3
720
16th to endNight
17%15%34%22%8%
768
April1st to 15thNight
23%12%34%24%4
718
16th to endNight
20%12%30%25%10%
690
May1st to 15thNight
21%10%29%29%8%
471
16th to endNight
16%325%38%15%1
375
June1st to 15thNight
19%5%19%40%15%
360
16th to endNight
13%119%47%17%
360
July1st to 15thNight
14%215%47%20%
340
16th to endNight
10%315%43%23%2
376
August1st to 15thNight
13%115%43%24%2
512
16th to endNight
15%112%36%29%4
764
September1st to 15thNight
17%320%35%20%2
720
16th to endNight
14%220%31%25%6%
717
October1st to 15thNight
21%6%21%32%16%2
684
16th to endNight
24%8%29%31%6%
704
November1st to 15thNight
17%9%31%31%9%1
700
16th to endNight
22%11%28%27%9%1
720
December1st to 15thNight
23%11%30%26%7%
720
16th to endNight
24%10%34%26%2
768
Page generated at 2017-10-07 14:07:47. Version ac04

Copyright 2017 A. Danko


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