Amagansett
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Amagansett clear sky chart from 2005-11-05 to 2018-02-22.

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
33%
15651
17%
48864
9%
15620
42%
15620
18%
32739

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
17%
780
16%
2716
6%
776
29%
776
13%
1819
January16th to endNight
16%
832
17%
2896
6%
832
32%
832
14%
1909
February1st to 15thNight
14%
764
15%
2330
3%
761
28%
761
14%
1632
February16th to endNight
19%
659
21%
1976
8%
659
37%
659
19%
1323
March1st to 15thNight
23%
720
17%
2160
8%
720
34%
720
17%
1447
March16th to endNight
26%
768
23%
2017
7%
768
39%
768
24%
1331
April1st to 15thNight
30%
718
18%
1796
5%
718
37%
718
22%
1273
April16th to endNight
36%
636
17%
1716
6%
636
41%
636
23%
1180
May1st to 15thNight
36%
540
15%
1620
7%
540
44%
540
17%
1148
May16th to endNight
41%
424
12%
1547
10%
424
46%
424
13%
1060
June1st to 15thNight
42%
360
13%
1440
15%
360
47%
360
15%
945
June16th to endNight
56%
360
13%
1440
15%
360
62%
360
21%
841
July1st to 15thNight
54%
340
11%
1360
17%
340
55%
340
19%
813
July16th to endNight
53%
376
16%
1418
16%
354
61%
354
20%
857
August1st to 15thNight
61%
533
18%
1604
13%
531
65%
531
27%
1009
August16th to endNight
63%
764
20%
1910
12%
764
65%
764
33%
1239
September1st to 15thNight
51%
720
20%
1845
13%
720
53%
720
29%
1238
September16th to endNight
48%
717
21%
1980
14%
717
54%
717
25%
1321
October1st to 15thNight
37%
720
20%
2019
14%
720
44%
720
22%
1368
October16th to endNight
29%
768
17%
2464
8%
768
40%
768
20%
1624
November1st to 15thNight
29%
760
17%
2472
10%
760
39%
760
16%
1674
November16th to endNight
25%
780
18%
2535
9%
780
37%
780
16%
1689
December1st to 15thNight
21%
780
12%
2691
5%
780
30%
780
10%
1939
December16th to endNight
13%
832
15%
2912
3%
832
29%
832
10%
2060

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%
49393
Night
17%6%25%42445%7%39%
49034
Cloud CoverDay
16%6%2442445%7%41%
49403
Night
17%7%25%42445%7%38%
49039
TransparencyDay
41%6%13%21%15%1
49081
Night
44%6%12%20%13%1
48864
SeeingDay
18%12%19%26%17%4
6391
Night
18%20%22%23%12%2
15652

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%6%245%3446%6%37%
1552
16th to endDay
17%7%25%424446%39%
1677
February1st to 15thDay
16%7%25%5%245%5%6%35%
1861
16th to endDay
16%6%245%245%47%41%
1644
March1st to 15thDay
18%5%25%433349%39%
1790
16th to endDay
16%7%3332345%5%44%
2205
April1st to 15thDay
19%5%23314447%43%
2152
16th to endDay
15%5%2442345%6%44%
2244
May1st to 15thDay
22%6%24323337%38%
2332
16th to endDay
14%6%2432345%9%41%
2576
June1st to 15thDay
19%5%24324448%39%
2520
16th to endDay
11%5%144245%6%9%44%
2520
July1st to 15thDay
10%5%15%4235%6%9%45%
2520
16th to endDay
12%424425%46%8%43%
2654
August1st to 15thDay
11%42343346%8%47%
2331
16th to endDay
10%424424447%49%
2292
September1st to 15thDay
12%31431345%7%50%
2115
16th to endDay
15%5%24423446%46%
1980
October1st to 15thDay
18%5%2442335%7%43%
1938
16th to endDay
14%5%1443445%6%44%
1758
November1st to 15thDay
21%6%23323436%42%
1716
16th to endDay
14%6%25%4245%5%7%40%
1755
December1st to 15thDay
19%8%35%434346%36%
1597
16th to endDay
21%8%46%43246%7%32%
1664
January1st to 15thNight
18%7%25%5%2335%7%36%
2716
16th to endNight
18%9%3442336%7%37%
2896
February1st to 15thNight
17%8%36%424447%36%
2329
16th to endNight
18%5%25%42445%7%39%
1976
March1st to 15thNight
18%7%2442345%7%39%
2147
16th to endNight
15%7%24423346%44%
2017
April1st to 15thNight
17%6%35%42445%6%39%
1796
16th to endNight
20%7%25%423347%38%
1716
May1st to 15thNight
17%8%35%5%345%47%34%
1620
16th to endNight
18%7%26%5%25%45%8%33%
1545
June1st to 15thNight
22%6%145%3335%6%37%
1440
16th to endNight
13%4244245%5%9%43%
1440
July1st to 15thNight
12%5%25%6%2447%9%38%
1440
16th to endNight
10%5%25%5%35%5%7%8%38%
1514
August1st to 15thNight
8%425%6%35%6%6%8%43%
1614
16th to endNight
11%4243235%5%8%47%
1910
September1st to 15thNight
15%5%24424447%43%
1845
16th to endNight
14%7%25%423435%44%
1980
October1st to 15thNight
17%7%25%5%24335%43%
2019
16th to endNight
18%5%26%5%23446%40%
2464
November1st to 15thNight
19%6%25%5%24345%40%
2472
16th to endNight
18%5%35%424446%39%
2535
December1st to 15thNight
20%8%46%5%3445%6%31%
2691
16th to endNight
19%7%26%5%35%45%7%31%
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%335%4447%7%35%
1552
16th to endDay
17%8%34423447%38%
1677
February1st to 15thDay
18%6%35%6%3446%6%35%
1861
16th to endDay
15%7%34424448%40%
1644
March1st to 15thDay
18%5%245%3445%8%38%
1800
16th to endDay
16%7%24424345%43%
2205
April1st to 15thDay
19%5%13324447%43%
2152
16th to endDay
15%6%2442335%6%43%
2244
May1st to 15thDay
22%7%25%323346%37%
2332
16th to endDay
15%6%25%5%235%5%7%40%
2576
June1st to 15thDay
19%5%244235%5%8%38%
2520
16th to endDay
11%5%244246%6%8%43%
2520
July1st to 15thDay
9%5%244245%5%9%44%
2520
16th to endDay
12%5%2443446%8%43%
2654
August1st to 15thDay
11%4144335%5%8%47%
2331
16th to endDay
10%42442445%7%48%
2292
September1st to 15thDay
12%5%143235%48%48%
2115
16th to endDay
15%5%245%23446%45%
1980
October1st to 15thDay
18%6%245%1345%6%43%
1938
16th to endDay
15%5%3343335%7%43%
1758
November1st to 15thDay
21%6%24313445%41%
1716
16th to endDay
15%6%25%435%5%5%7%39%
1755
December1st to 15thDay
19%8%35%5%24447%34%
1597
16th to endDay
21%9%36%42246%6%31%
1664
January1st to 15thNight
19%6%3442446%8%34%
2716
16th to endNight
18%9%2442346%6%36%
2896
February1st to 15thNight
17%8%35%43445%6%35%
2322
16th to endNight
17%6%2442445%7%39%
1976
March1st to 15thNight
17%7%25%5%2435%7%38%
2160
16th to endNight
17%6%24323346%44%
2016
April1st to 15thNight
18%7%25%423446%40%
1796
16th to endNight
19%6%35%323347%38%
1716
May1st to 15thNight
17%9%36%5%3445%6%34%
1620
16th to endNight
18%7%25%5%345%5%7%32%
1545
June1st to 15thNight
21%7%245%24346%36%
1440
16th to endNight
13%42442445%9%42%
1440
July1st to 15thNight
12%6%25%4345%7%9%39%
1440
16th to endNight
10%6%245%35%6%8%9%36%
1514
August1st to 15thNight
8%4245%35%6%6%8%43%
1614
16th to endNight
11%42442346%8%47%
1910
September1st to 15thNight
15%6%144345%5%7%42%
1845
16th to endNight
15%7%25%42433444%
1980
October1st to 15thNight
17%7%35%32335%5%41%
2019
16th to endNight
18%6%25%5%23447%39%
2464
November1st to 15thNight
19%6%25%42444439%
2472
16th to endNight
17%6%35%425%45%7%36%
2535
December1st to 15thNight
20%9%36%5%3445%5%30%
2691
16th to endNight
20%8%27%5%35%45%6%30%
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
46%7%14%19%9%1
1553
16th to endDay
45%5%14%21%12%1
1677
February1st to 15thDay
47%5%15%19%10%
1864
16th to endDay
41%5%13%25%12%1
1644
March1st to 15thDay
44%5%15%23%9%2
1800
16th to endDay
42%411%20%17%3
2205
April1st to 15thDay
40%5%12%21%17%3
2152
16th to endDay
40%49%22%19%3
2244
May1st to 15thDay
46%6%9%20%14%2
2332
16th to endDay
41%8%14%20%12%2
2580
June1st to 15thDay
43%6%13%22%13%
2520
16th to endDay
35%7%15%25%15%1
2520
July1st to 15thDay
36%7%14%22%17%1
2371
16th to endDay
36%8%14%24%13%3
2487
August1st to 15thDay
32%7%17%22%17%1
2317
16th to endDay
34%7%10%25%19%1
2292
September1st to 15thDay
33%8%13%21%22%1
2115
16th to endDay
39%5%9%21%22%1
1980
October1st to 15thDay
41%5%12%20%17%2
1938
16th to endDay
40%5%13%22%15%1
1758
November1st to 15thDay
44%5%15%19%14%1
1716
16th to endDay
43%5%14%23%10%1
1755
December1st to 15thDay
48%7%17%14%11%
1597
16th to endDay
52%6%15%16%9%
1664
January1st to 15thNight
46%6%15%20%10%1
2716
16th to endNight
46%5%13%20%12%
2896
February1st to 15thNight
48%6%12%20%9%1
2330
16th to endNight
44%411%23%13%1
1976
March1st to 15thNight
44%5%14%18%13%2
2160
16th to endNight
40%410%21%18%4
2017
April1st to 15thNight
44%6%10%20%16%2
1796
16th to endNight
45%411%18%16%4
1716
May1st to 15thNight
49%6%10%18%12%3
1620
16th to endNight
48%7%14%16%10%2
1547
June1st to 15thNight
47%6%11%17%15%1
1440
16th to endNight
37%6%14%23%16%1
1440
July1st to 15thNight
38%8%14%23%14%1
1360
16th to endNight
37%10%15%23%10%2
1418
August1st to 15thNight
34%9%14%24%15%1
1604
16th to endNight
33%8%11%26%19%1
1910
September1st to 15thNight
40%5%11%23%18%
1845
16th to endNight
42%47%19%22%1
1980
October1st to 15thNight
44%5%9%21%15%2
2019
16th to endNight
44%5%14%21%13%
2464
November1st to 15thNight
47%5%11%18%14%2
2472
16th to endNight
46%5%13%21%11%2
2535
December1st to 15thNight
53%7%14%15%8%
2691
16th to endNight
52%6%14%18%8%
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%15%40%21%5%1
90
16th to endDay
28%5%40%20%6%
99
February1st to 15thDay
24%16%35%20%2
287
16th to endDay
16%18%33%24%6%
265
March1st to 15thDay
22%21%27%24%4
270
16th to endDay
16%17%34%22%7%1
288
April1st to 15thDay
19%16%21%31%10%
270
16th to endDay
19%13%17%34%12%2
270
May1st to 15thDay
26%14%20%25%11%1
288
16th to endDay
21%9%13%28%21%5%
331
June1st to 15thDay
20%10%15%25%23%5%
315
16th to endDay
14%9%11%38%20%4
315
July1st to 15thDay
13%7%8%31%33%5%
305
16th to endDay
11%9%8%29%32%7%
326
August1st to 15thDay
13%6%7%30%35%7%
313
16th to endDay
9%5%8%31%31%14%
332
September1st to 15thDay
15%6%16%27%23%9%
315
16th to endDay
23%5%15%21%22%11%
314
October1st to 15thDay
20%9%15%26%22%6%
315
16th to endDay
17%12%26%26%14%1
295
November1st to 15thDay
22%15%21%23%14%2
280
16th to endDay
13%24%25%23%12%
285
December1st to 15thDay
24%14%29%18%11%
127
16th to endDay
30%14%35%19%
96
January1st to 15thNight
18%30%30%17%3
780
16th to endNight
21%25%31%18%1
832
February1st to 15thNight
19%26%36%17%1
764
16th to endNight
19%25%32%17%5%
659
March1st to 15thNight
20%24%26%21%6%
720
16th to endNight
16%22%28%22%7%1
768
April1st to 15thNight
19%20%25%26%7%
718
16th to endNight
19%18%19%27%13%1
636
May1st to 15thNight
17%18%22%25%13%3
540
16th to endNight
20%18%10%31%16%2
425
June1st to 15thNight
19%18%11%26%21%2
360
16th to endNight
13%16%7%35%25%1
360
July1st to 15thNight
12%13%10%33%27%2
340
16th to endNight
13%16%8%28%28%3
376
August1st to 15thNight
10%9%7%39%30%2
533
16th to endNight
11%9%7%29%32%9%
764
September1st to 15thNight
15%10%14%31%21%6%
720
16th to endNight
18%9%14%28%21%8%
717
October1st to 15thNight
21%12%20%25%15%3
720
16th to endNight
20%16%29%21%11%1
768
November1st to 15thNight
20%21%23%21%11%2
760
16th to endNight
16%28%24%20%8%
780
December1st to 15thNight
23%26%22%18%6%
780
16th to endNight
23%30%29%15%1
832
Page generated at 2018-02-23 11:21:28. Version ac04

Copyright 2018 A. Danko


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