Robert Moses State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Robert Moses State Park clear sky chart from 2005-11-05 to 2017-03-21.

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
32%
14517
18%
45245
9%
14486
43%
14486
20%
29411

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
19%
720
19%
2506
8%
716
34%
716
15%
1602
January16th to endNight
16%
768
19%
2622
6%
768
33%
768
15%
1676
February1st to 15thNight
16%
704
16%
2189
4%
701
30%
701
17%
1463
February16th to endNight
21%
631
24%
1893
9%
631
41%
631
20%
1200
March1st to 15thNight
22%
720
18%
2160
8%
720
35%
720
20%
1413
March16th to endNight
25%
728
23%
1899
8%
728
37%
728
24%
1247
April1st to 15thNight
27%
658
17%
1646
6%
658
34%
658
22%
1146
April16th to endNight
33%
624
18%
1614
5%
624
40%
624
24%
1095
May1st to 15thNight
34%
495
17%
1485
8%
495
42%
495
18%
1026
May16th to endNight
41%
349
14%
1376
13%
349
48%
349
14%
897
June1st to 15thNight
40%
330
14%
1320
15%
330
46%
330
15%
871
June16th to endNight
56%
330
14%
1320
15%
330
62%
330
20%
775
July1st to 15thNight
52%
310
13%
1240
16%
310
55%
310
19%
758
July16th to endNight
53%
348
16%
1306
15%
326
62%
326
20%
765
August1st to 15thNight
57%
513
20%
1494
14%
511
61%
511
28%
921
August16th to endNight
61%
700
17%
1750
9%
700
63%
700
31%
1159
September1st to 15thNight
53%
660
23%
1664
14%
660
56%
660
31%
1111
September16th to endNight
50%
657
23%
1815
15%
657
56%
657
28%
1154
October1st to 15thNight
37%
660
21%
1895
14%
660
45%
660
23%
1252
October16th to endNight
29%
704
18%
2222
8%
704
43%
704
21%
1444
November1st to 15thNight
28%
700
20%
2277
12%
700
41%
700
20%
1426
November16th to endNight
25%
720
17%
2344
8%
720
37%
720
17%
1525
December1st to 15thNight
20%
720
13%
2520
5%
720
30%
720
12%
1704
December16th to endNight
15%
768
18%
2688
4%
768
32%
768
13%
1781

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
15%5%2442445%7%42%
45627
Night
16%6%24424447%41%
45415
Cloud CoverDay
15%5%2442445%7%42%
45637
Night
16%6%2442445%7%41%
45420
TransparencyDay
39%6%13%22%15%1
45315
Night
42%5%12%21%15%2
45245
SeeingDay
17%14%20%27%17%3
5147
Night
17%21%23%24%12%1
14518

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
15%6%25%5%3435%5%41%
1432
16th to endDay
15%6%34423449%41%
1601
February1st to 15thDay
16%5%25%43435%7%40%
1672
16th to endDay
14%5%25%5%35%35%6%42%
1580
March1st to 15thDay
17%7%24424448%39%
1790
16th to endDay
16%7%33423346%44%
2093
April1st to 15thDay
19%5%34424347%41%
1972
16th to endDay
15%5%1432445%7%45%
2016
May1st to 15thDay
20%7%23434348%37%
2140
16th to endDay
16%5%244245%6%8%39%
2394
June1st to 15thDay
20%5%24324448%37%
2310
16th to endDay
9%324435%5%5%8%46%
2310
July1st to 15thDay
8%4345%35%5%6%8%44%
2310
16th to endDay
11%4244345%6%9%42%
2458
August1st to 15thDay
9%41432446%8%49%
2114
16th to endDay
12%32432346%6%49%
2100
September1st to 15thDay
12%42442346%7%47%
1966
16th to endDay
14%5%24422347%46%
1815
October1st to 15thDay
17%6%14424346%43%
1733
16th to endDay
17%42332436%7%44%
1650
November1st to 15thDay
18%5%24333335%46%
1581
16th to endDay
14%5%25%5%2446%8%41%
1614
December1st to 15thDay
17%7%24335%5%6%5%39%
1440
16th to endDay
22%7%2442345%6%35%
1536
January1st to 15thNight
18%5%24424347%40%
2506
16th to endNight
18%7%23324436%41%
2622
February1st to 15thNight
15%8%35%4245%5%6%39%
2188
16th to endNight
17%5%23424347%44%
1893
March1st to 15thNight
18%6%25%423347%43%
2147
16th to endNight
16%7%33313346%46%
1899
April1st to 15thNight
18%7%24434447%38%
1646
16th to endNight
17%6%2442235%7%41%
1614
May1st to 15thNight
17%8%35%435%35%6%36%
1485
16th to endNight
18%5%26%3245%5%8%36%
1374
June1st to 15thNight
22%5%35%323347%38%
1320
16th to endNight
9%425%5%345%5%10%42%
1320
July1st to 15thNight
10%5%34425%5%7%10%39%
1320
16th to endNight
9%435%5%35%5%7%8%40%
1402
August1st to 15thNight
8%4244346%6%7%45%
1504
16th to endNight
12%4245%3445%9%43%
1750
September1st to 15thNight
14%42442446%6%45%
1664
16th to endNight
15%5%25%433345%48%
1815
October1st to 15thNight
17%6%25%423335%43%
1895
16th to endNight
18%5%15%433336%43%
2222
November1st to 15thNight
17%6%24423235%47%
2277
16th to endNight
17%6%25%42445%6%40%
2344
December1st to 15thNight
20%7%25%42335%7%36%
2520
16th to endNight
20%6%25%42345%6%37%
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
15%7%15%434346%40%
1432
16th to endDay
15%7%24424349%40%
1601
February1st to 15thDay
16%5%36%435%35%6%40%
1672
16th to endDay
14%5%25%5%3445%6%42%
1580
March1st to 15thDay
17%7%2442345%8%38%
1800
16th to endDay
16%7%23423345%44%
2093
April1st to 15thDay
18%5%34423347%41%
1972
16th to endDay
15%5%144235%5%6%45%
2016
May1st to 15thDay
20%7%2343425%7%37%
2140
16th to endDay
15%5%244345%6%8%39%
2394
June1st to 15thDay
20%5%243245%48%37%
2310
16th to endDay
9%325%5%35%5%5%8%46%
2310
July1st to 15thDay
8%4345%35%5%6%10%43%
2310
16th to endDay
10%5%34435%5%7%9%42%
2458
August1st to 15thDay
9%5%2433436%8%49%
2114
16th to endDay
11%42442345%7%49%
2100
September1st to 15thDay
11%5%244135%6%7%47%
1966
16th to endDay
14%6%24423347%46%
1815
October1st to 15thDay
17%6%24423345%44%
1733
16th to endDay
17%42333346%8%43%
1650
November1st to 15thDay
18%6%24333336%45%
1581
16th to endDay
14%5%245%2445%8%41%
1614
December1st to 15thDay
16%7%24425%5%6%5%39%
1440
16th to endDay
21%7%245%2335%6%36%
1536
January1st to 15thNight
18%6%2442435%8%39%
2506
16th to endNight
18%7%23324446%41%
2622
February1st to 15thNight
14%8%35%4245%5%6%38%
2181
16th to endNight
17%5%23423447%44%
1893
March1st to 15thNight
18%6%24423347%42%
2160
16th to endNight
16%7%33313346%45%
1898
April1st to 15thNight
18%7%24424447%38%
1646
16th to endNight
17%6%3443335%6%42%
1614
May1st to 15thNight
17%8%25%435%45%6%36%
1485
16th to endNight
18%6%25%42446%8%36%
1374
June1st to 15thNight
22%435%423347%37%
1320
16th to endNight
8%425%6%25%5%6%10%42%
1320
July1st to 15thNight
10%5%35%435%5%7%9%39%
1320
16th to endNight
8%5%35%426%6%6%9%40%
1402
August1st to 15thNight
8%424435%6%6%7%45%
1504
16th to endNight
12%425%5%3435%9%44%
1750
September1st to 15thNight
14%4145%345%5%6%44%
1664
16th to endNight
14%5%25%424245%48%
1815
October1st to 15thNight
18%6%35%423335%43%
1895
16th to endNight
18%5%25%434345%42%
2222
November1st to 15thNight
17%6%2432323447%
2277
16th to endNight
17%6%25%42345%7%39%
2344
December1st to 15thNight
21%6%2442345%8%35%
2520
16th to endNight
20%6%25%43345%7%37%
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
44%6%14%22%10%2
1433
16th to endDay
41%5%16%23%11%2
1601
February1st to 15thDay
43%6%14%21%13%
1675
16th to endDay
42%5%11%26%12%1
1580
March1st to 15thDay
43%5%15%23%10%1
1800
16th to endDay
41%5%11%22%16%2
2093
April1st to 15thDay
41%411%22%16%3
1972
16th to endDay
37%410%23%20%3
2016
May1st to 15thDay
46%5%10%20%15%1
2140
16th to endDay
41%8%15%19%13%2
2398
June1st to 15thDay
43%7%14%21%11%
2310
16th to endDay
34%7%16%26%14%1
2310
July1st to 15thDay
34%8%14%24%16%1
2161
16th to endDay
33%8%15%26%13%2
2291
August1st to 15thDay
30%7%16%27%15%1
2100
16th to endDay
33%7%11%25%19%2
2100
September1st to 15thDay
34%6%14%21%20%1
1966
16th to endDay
38%5%11%22%21%1
1815
October1st to 15thDay
41%5%11%22%17%1
1733
16th to endDay
38%5%14%24%16%1
1650
November1st to 15thDay
42%5%12%21%17%1
1581
16th to endDay
41%6%15%23%11%2
1614
December1st to 15thDay
44%6%16%17%13%
1440
16th to endDay
49%416%18%11%
1536
January1st to 15thNight
44%414%21%12%2
2506
16th to endNight
44%413%23%13%1
2622
February1st to 15thNight
44%5%13%22%11%1
2189
16th to endNight
39%5%11%24%17%2
1893
March1st to 15thNight
43%414%20%13%3
2160
16th to endNight
40%49%22%18%4
1899
April1st to 15thNight
44%5%12%19%15%3
1646
16th to endNight
42%5%9%16%22%3
1614
May1st to 15thNight
46%5%11%17%14%3
1485
16th to endNight
44%8%14%15%14%1
1376
June1st to 15thNight
47%6%11%17%15%1
1320
16th to endNight
36%8%13%27%13%1
1320
July1st to 15thNight
39%8%14%23%13%1
1240
16th to endNight
36%8%14%27%11%2
1306
August1st to 15thNight
33%8%14%25%15%2
1494
16th to endNight
36%7%12%24%17%1
1750
September1st to 15thNight
37%7%11%23%19%
1664
16th to endNight
38%48%21%24%1
1815
October1st to 15thNight
43%410%22%16%2
1895
16th to endNight
43%412%22%15%1
2222
November1st to 15thNight
42%411%20%18%3
2277
16th to endNight
44%5%13%24%10%2
2344
December1st to 15thNight
48%6%16%16%10%
2520
16th to endNight
46%6%15%20%10%1
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%21%31%26%6%
60
16th to endDay
20%8%37%32%2
75
February1st to 15thDay
20%21%35%21%1
188
16th to endDay
14%20%33%24%7%
239
March1st to 15thDay
22%17%31%22%5%
270
16th to endDay
17%21%28%24%6%1
245
April1st to 15thDay
20%22%24%23%8%
210
16th to endDay
15%17%20%32%12%1
210
May1st to 15thDay
32%16%18%19%11%2
228
16th to endDay
17%13%15%28%23%1
267
June1st to 15thDay
20%12%18%25%20%1
255
16th to endDay
9%12%9%43%21%2
255
July1st to 15thDay
10%8%11%35%31%2
245
16th to endDay
10%12%9%35%28%3
270
August1st to 15thDay
11%7%11%32%32%5%
253
16th to endDay
13%6%6%30%31%11%
268
September1st to 15thDay
15%6%18%25%24%9%
255
16th to endDay
18%7%13%28%22%9%
254
October1st to 15thDay
23%9%15%24%22%5%
255
16th to endDay
16%15%30%25%12%
252
November1st to 15thDay
20%18%21%20%15%2
235
16th to endDay
14%25%26%24%7%2
234
December1st to 15thDay
16%13%33%28%6%1
60
16th to endDay
37%7%29%23%1
64
January1st to 15thNight
15%31%29%19%3
720
16th to endNight
20%28%32%17%1
768
February1st to 15thNight
15%27%36%18%1
704
16th to endNight
16%27%30%20%4
631
March1st to 15thNight
20%24%28%20%5%
720
16th to endNight
17%23%29%20%7%1
728
April1st to 15thNight
19%23%26%23%6%
658
16th to endNight
16%20%23%27%10%1
624
May1st to 15thNight
20%20%20%25%11%2
495
16th to endNight
18%21%10%29%18%2
350
June1st to 15thNight
19%19%14%27%18%
330
16th to endNight
8%19%7%41%21%1
330
July1st to 15thNight
10%14%12%34%25%2
310
16th to endNight
9%18%10%33%22%4
348
August1st to 15thNight
10%11%11%39%25%1
513
16th to endNight
14%9%6%29%32%7%
700
September1st to 15thNight
14%11%15%31%22%5%
660
16th to endNight
16%11%14%27%22%7%
657
October1st to 15thNight
20%15%20%24%17%1
660
16th to endNight
20%18%27%24%9%
704
November1st to 15thNight
17%23%26%17%13%1
700
16th to endNight
16%26%27%20%8%
720
December1st to 15thNight
22%28%24%16%6%1
720
16th to endNight
22%28%30%16%1
768
Page generated at 2017-03-22 02:42:25. Version ac04

Copyright 2017 A. Danko


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