Montauk Point State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Montauk Point State Park clear sky chart from 2005-11-05 to 2018-02-14.

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
37%
15612
17%
48761
10%
15581
45%
15581
21%
32720

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
18%
780
15%
2716
6%
776
31%
776
15%
1823
January16th to endNight
18%
832
17%
2909
6%
832
34%
832
15%
1915
February1st to 15thNight
15%
759
16%
2304
4%
757
30%
757
16%
1615
February16th to endNight
21%
631
21%
1893
7%
631
39%
631
21%
1260
March1st to 15thNight
28%
720
17%
2160
9%
720
39%
720
20%
1461
March16th to endNight
30%
768
22%
2022
8%
768
42%
768
27%
1348
April1st to 15thNight
38%
718
17%
1796
7%
718
43%
718
27%
1263
April16th to endNight
42%
624
16%
1704
7%
624
47%
624
25%
1195
May1st to 15thNight
43%
540
15%
1620
9%
540
49%
540
22%
1150
May16th to endNight
48%
436
10%
1558
10%
435
51%
435
16%
1096
June1st to 15thNight
48%
360
12%
1440
15%
360
53%
360
16%
961
June16th to endNight
63%
360
13%
1440
18%
360
66%
360
23%
844
July1st to 15thNight
62%
340
11%
1360
17%
340
62%
340
19%
827
July16th to endNight
65%
376
15%
1418
18%
354
68%
354
21%
866
August1st to 15thNight
67%
527
17%
1598
14%
525
68%
525
29%
1005
August16th to endNight
68%
764
20%
1910
12%
764
68%
764
36%
1220
September1st to 15thNight
55%
720
20%
1854
13%
720
57%
720
31%
1242
September16th to endNight
52%
717
21%
1980
17%
717
55%
717
28%
1328
October1st to 15thNight
41%
720
21%
2007
15%
720
48%
720
25%
1353
October16th to endNight
31%
768
17%
2475
9%
768
42%
768
21%
1622
November1st to 15thNight
33%
760
17%
2472
11%
760
44%
760
19%
1654
November16th to endNight
29%
780
18%
2535
10%
780
39%
780
18%
1696
December1st to 15thNight
23%
780
12%
2678
5%
780
32%
780
12%
1921
December16th to endNight
16%
832
15%
2912
4%
832
31%
832
14%
2055

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
16%6%2442445%7%42%
49320
Night
17%7%25%42445%6%38%
48931
Cloud CoverDay
16%6%2442445%7%41%
49330
Night
17%7%35%42445%6%37%
48936
TransparencyDay
41%6%13%22%15%1
49008
Night
45%6%12%20%13%1
48761
SeeingDay
20%5%22%30%18%4
6377
Night
20%7%27%27%14%2
15613

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
17%7%245%45%37%6%36%
1552
16th to endDay
17%7%3442435%6%38%
1664
February1st to 15thDay
17%6%45%5%35%5%5%7%33%
1856
16th to endDay
15%6%25%325%35%7%40%
1580
March1st to 15thDay
19%5%1442335%7%40%
1790
16th to endDay
16%7%23323345%44%
2202
April1st to 15thDay
19%5%1322445%6%44%
2152
16th to endDay
16%5%25%42345%6%44%
2255
May1st to 15thDay
23%8%25%313346%38%
2332
16th to endDay
16%6%2442345%8%40%
2567
June1st to 15thDay
19%6%2442445%7%39%
2520
16th to endDay
11%5%2432446%10%43%
2520
July1st to 15thDay
10%5%2442445%10%44%
2520
16th to endDay
12%4245%2445%9%43%
2654
August1st to 15thDay
11%41342446%8%47%
2335
16th to endDay
11%4245%23447%50%
2292
September1st to 15thDay
12%414323447%50%
2106
16th to endDay
14%6%24423447%47%
1980
October1st to 15thDay
17%6%25%322346%44%
1950
16th to endDay
14%6%2432445%6%44%
1749
November1st to 15thDay
21%6%23323435%41%
1716
16th to endDay
15%5%345%2446%7%39%
1755
December1st to 15thDay
19%8%35%424436%35%
1609
16th to endDay
22%8%36%5%2345%7%32%
1664
January1st to 15thNight
19%7%35%5%2346%7%34%
2716
16th to endNight
18%9%3442345%7%36%
2909
February1st to 15thNight
16%9%36%43445%6%35%
2303
16th to endNight
16%6%245%345%6%6%38%
1893
March1st to 15thNight
18%7%2432445%7%38%
2147
16th to endNight
16%8%24424345%43%
2022
April1st to 15thNight
17%7%25%333346%40%
1796
16th to endNight
20%6%245%24446%38%
1704
May1st to 15thNight
18%8%346%34447%34%
1620
16th to endNight
19%7%26%426%45%7%32%
1556
June1st to 15thNight
21%7%35%424445%37%
1440
16th to endNight
13%43443446%8%42%
1440
July1st to 15thNight
12%5%245%35%5%7%9%37%
1440
16th to endNight
10%6%34436%5%8%7%37%
1514
August1st to 15thNight
9%5%25%4346%7%7%43%
1608
16th to endNight
11%4233245%5%8%48%
1910
September1st to 15thNight
14%6%25%42445%7%42%
1854
16th to endNight
14%6%26%5%2433445%
1980
October1st to 15thNight
16%6%35%5%24345%41%
2007
16th to endNight
19%5%25%42445%6%39%
2475
November1st to 15thNight
19%7%25%433346%39%
2472
16th to endNight
18%7%34433447%37%
2535
December1st to 15thNight
21%8%36%5%3445%6%30%
2678
16th to endNight
20%8%27%42447%6%30%
2912

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
17%7%246%3437%6%34%
1552
16th to endDay
17%7%345%2335%7%37%
1664
February1st to 15thDay
17%7%36%5%25%46%7%33%
1856
16th to endDay
15%6%25%425%36%6%40%
1580
March1st to 15thDay
19%5%245%1445%7%40%
1800
16th to endDay
16%8%23323445%44%
2202
April1st to 15thDay
19%5%1332345%7%43%
2152
16th to endDay
15%5%2432345%6%44%
2255
May1st to 15thDay
23%8%24313246%37%
2332
16th to endDay
15%7%3442445%8%38%
2567
June1st to 15thDay
19%6%2442435%8%38%
2520
16th to endDay
11%6%244245%6%9%43%
2520
July1st to 15thDay
10%5%2442446%9%45%
2520
16th to endDay
12%4244345%6%7%44%
2654
August1st to 15thDay
11%41442345%8%47%
2335
16th to endDay
11%41442345%6%50%
2292
September1st to 15thDay
12%41442335%7%49%
2106
16th to endDay
14%6%245%23337%45%
1980
October1st to 15thDay
17%6%24423247%43%
1950
16th to endDay
15%5%2432345%7%43%
1749
November1st to 15thDay
22%5%24323345%41%
1716
16th to endDay
15%5%36%43446%7%38%
1755
December1st to 15thDay
20%8%36%424445%35%
1609
16th to endDay
22%8%36%43245%7%30%
1664
January1st to 15thNight
19%7%35%5%3446%7%32%
2716
16th to endNight
19%9%2442345%6%35%
2909
February1st to 15thNight
16%9%36%434346%35%
2296
16th to endNight
16%6%245%3446%6%38%
1893
March1st to 15thNight
19%7%3442435%7%38%
2160
16th to endNight
16%8%24423336%44%
2021
April1st to 15thNight
16%8%25%324447%40%
1796
16th to endNight
20%6%25%423446%38%
1704
May1st to 15thNight
18%7%45%5%25%446%34%
1620
16th to endNight
19%8%25%5%35%5%6%7%32%
1556
June1st to 15thNight
22%6%35%424445%37%
1440
16th to endNight
13%42442446%8%42%
1440
July1st to 15thNight
11%6%25%426%5%6%9%38%
1440
16th to endNight
10%7%34436%5%8%8%37%
1514
August1st to 15thNight
8%5%24435%5%7%8%42%
1608
16th to endNight
12%5%2432445%8%48%
1910
September1st to 15thNight
14%6%245%3445%8%41%
1854
16th to endNight
15%7%35%5%33335%43%
1980
October1st to 15thNight
18%6%35%423445%41%
2007
16th to endNight
19%5%25%5%2445%7%38%
2475
November1st to 15thNight
19%7%25%424345%38%
2472
16th to endNight
18%7%35%4245%47%36%
2535
December1st to 15thNight
21%9%46%5%3445%6%28%
2678
16th to endNight
20%8%36%5%35%46%6%29%
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
47%6%14%20%9%1
1553
16th to endDay
45%413%22%12%1
1664
February1st to 15thDay
48%6%14%19%10%
1859
16th to endDay
42%5%12%25%12%1
1580
March1st to 15thDay
43%416%23%9%2
1800
16th to endDay
42%411%21%17%3
2202
April1st to 15thDay
39%5%11%21%18%2
2152
16th to endDay
39%5%8%23%17%4
2255
May1st to 15thDay
48%5%10%19%13%2
2332
16th to endDay
42%8%14%19%12%2
2571
June1st to 15thDay
44%7%11%22%13%
2520
16th to endDay
35%8%15%24%15%1
2520
July1st to 15thDay
35%8%14%23%15%1
2371
16th to endDay
36%7%14%24%13%2
2487
August1st to 15thDay
33%9%16%22%17%1
2321
16th to endDay
33%7%10%27%19%1
2292
September1st to 15thDay
33%7%13%21%22%1
2106
16th to endDay
38%5%9%22%22%1
1980
October1st to 15thDay
41%5%11%22%16%2
1950
16th to endDay
37%6%14%23%15%1
1749
November1st to 15thDay
46%415%17%14%1
1716
16th to endDay
42%6%13%23%12%1
1755
December1st to 15thDay
49%5%15%15%12%
1609
16th to endDay
52%5%15%16%10%
1664
January1st to 15thNight
47%6%14%19%10%1
2716
16th to endNight
47%413%20%12%1
2909
February1st to 15thNight
49%5%12%20%10%1
2304
16th to endNight
44%5%12%22%14%2
1893
March1st to 15thNight
45%5%13%19%12%3
2160
16th to endNight
42%49%19%18%5%
2022
April1st to 15thNight
44%5%11%19%15%2
1796
16th to endNight
46%5%9%18%16%4
1704
May1st to 15thNight
49%5%10%17%12%3
1620
16th to endNight
50%8%14%15%9%2
1558
June1st to 15thNight
48%6%11%16%15%1
1440
16th to endNight
37%7%14%23%15%1
1440
July1st to 15thNight
40%8%14%21%13%
1360
16th to endNight
37%9%17%22%10%2
1418
August1st to 15thNight
35%9%15%23%15%1
1598
16th to endNight
33%7%13%26%18%1
1910
September1st to 15thNight
40%5%11%23%18%1
1854
16th to endNight
44%37%19%22%1
1980
October1st to 15thNight
44%49%22%15%2
2007
16th to endNight
44%5%15%20%13%1
2475
November1st to 15thNight
46%5%12%18%14%3
2472
16th to endNight
46%6%12%21%11%2
2535
December1st to 15thNight
54%6%14%15%9%
2678
16th to endNight
52%6%13%17%9%
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
16%17%42%16%5%1
90
16th to endDay
26%10%37%22%3
96
February1st to 15thDay
27%9%42%18%2
292
16th to endDay
17%9%38%27%6%
239
March1st to 15thDay
23%10%31%28%5%
270
16th to endDay
20%7%35%26%8%1
288
April1st to 15thDay
22%424%35%11%
270
16th to endDay
22%419%37%12%3
270
May1st to 15thDay
28%327%26%10%2
288
16th to endDay
22%115%30%24%4
331
June1st to 15thDay
21%117%31%24%3
315
16th to endDay
16%16%40%20%4
315
July1st to 15thDay
15%19%38%30%4
305
16th to endDay
13%19%34%34%6%
326
August1st to 15thDay
15%9%34%34%6%
313
16th to endDay
12%8%34%30%13%
332
September1st to 15thDay
14%19%31%24%9%
315
16th to endDay
23%116%27%21%9%
314
October1st to 15thDay
23%5%14%28%22%5%
315
16th to endDay
17%9%28%30%13%1
293
November1st to 15thDay
24%6%23%28%13%2
280
16th to endDay
18%13%28%24%13%
285
December1st to 15thDay
21%14%28%24%10%
139
16th to endDay
27%17%37%16%1
96
January1st to 15thNight
23%16%36%19%4
780
16th to endNight
25%14%37%20%2
832
February1st to 15thNight
21%14%43%19%1
760
16th to endNight
19%13%41%20%4
631
March1st to 15thNight
22%10%33%25%7%
720
16th to endNight
19%6%35%26%8%1
768
April1st to 15thNight
22%430%33%9%
718
16th to endNight
23%224%33%14%1
624
May1st to 15thNight
20%324%33%14%4
540
16th to endNight
22%316%33%21%3
436
June1st to 15thNight
23%215%30%26%2
360
16th to endNight
15%111%36%32%1
360
July1st to 15thNight
15%110%38%30%3
340
16th to endNight
11%110%39%32%5%
376
August1st to 15thNight
10%11%40%32%3
527
16th to endNight
13%28%31%32%10%
764
September1st to 15thNight
17%17%33%24%6%
720
16th to endNight
20%115%28%24%8%
717
October1st to 15thNight
21%5%24%27%18%3
720
16th to endNight
21%9%33%24%10%1
768
November1st to 15thNight
22%10%27%25%12%1
760
16th to endNight
22%12%28%26%8%1
780
December1st to 15thNight
25%15%30%20%7%1
780
16th to endNight
24%14%40%17%2
832
Page generated at 2018-02-15 10:58:45. Version ac04

Copyright 2018 A. Danko


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