Caumsett State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Caumsett State Park clear sky chart from 2005-11-05 to 2017-10-31.

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%
15191
19%
47361
10%
15160
44%
15160
23%
30365

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
21%
720
21%
2506
8%
716
38%
716
18%
1555
January16th to endNight
18%
768
20%
2621
6%
768
37%
768
19%
1628
February1st to 15thNight
17%
704
18%
2203
4%
701
33%
701
18%
1449
February16th to endNight
22%
631
25%
1893
9%
631
43%
631
23%
1198
March1st to 15thNight
23%
720
18%
2160
7%
720
37%
720
22%
1425
March16th to endNight
23%
768
24%
1995
8%
768
35%
768
27%
1311
April1st to 15thNight
27%
718
16%
1796
5%
718
33%
718
24%
1264
April16th to endNight
31%
682
18%
1762
5%
682
38%
682
26%
1210
May1st to 15thNight
29%
528
17%
1608
6%
528
38%
528
20%
1104
May16th to endNight
42%
374
15%
1497
12%
374
51%
374
18%
949
June1st to 15thNight
43%
360
15%
1440
14%
360
51%
360
18%
913
June16th to endNight
60%
360
15%
1440
17%
360
66%
360
25%
826
July1st to 15thNight
54%
340
12%
1360
15%
340
56%
340
21%
835
July16th to endNight
58%
376
16%
1418
16%
354
65%
354
24%
821
August1st to 15thNight
57%
545
19%
1616
14%
543
60%
543
31%
973
August16th to endNight
59%
764
18%
1910
10%
764
61%
764
33%
1263
September1st to 15thNight
49%
720
22%
1809
11%
720
54%
720
33%
1200
September16th to endNight
50%
717
24%
1980
18%
717
56%
717
31%
1272
October1st to 15thNight
38%
720
20%
2079
13%
720
46%
720
25%
1354
October16th to endNight
30%
768
22%
2419
11%
768
44%
768
25%
1506
November1st to 15thNight
31%
700
22%
2277
11%
700
46%
700
22%
1422
November16th to endNight
27%
720
21%
2364
11%
720
40%
720
21%
1493
December1st to 15thNight
22%
720
16%
2520
6%
720
35%
720
18%
1621
December16th to endNight
16%
768
19%
2688
5%
768
33%
768
16%
1773

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%5%2442445%7%42%
48393
Night
16%6%2442445%6%42%
47531
Cloud CoverDay
15%5%2442445%7%42%
48403
Night
16%6%2442445%6%42%
47536
TransparencyDay
41%5%12%22%15%2
48081
Night
42%5%11%22%15%2
47361
SeeingDay
18%8%27%27%14%3
5995
Night
19%10%31%27%10%1
15192

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%245%3445%7%40%
1432
16th to endDay
14%7%25%42445%7%41%
1602
February1st to 15thDay
16%5%26%5%24447%41%
1657
16th to endDay
15%426%434446%43%
1580
March1st to 15thDay
17%6%2443445%8%38%
1790
16th to endDay
17%6%34423346%43%
2226
April1st to 15thDay
17%7%34423346%42%
2152
16th to endDay
16%414435%446%45%
2196
May1st to 15thDay
19%6%25%42345%7%37%
2352
16th to endDay
16%5%23435%45%9%40%
2618
June1st to 15thDay
18%5%24424448%39%
2520
16th to endDay
10%5%25%435%5%5%9%42%
2520
July1st to 15thDay
9%425%425%6%6%9%42%
2520
16th to endDay
10%5%25%435%5%6%9%41%
2654
August1st to 15thDay
10%4245%346%6%9%43%
2317
16th to endDay
11%32441445%8%47%
2292
September1st to 15thDay
11%42443445%7%47%
2151
16th to endDay
13%6%24423446%47%
1980
October1st to 15thDay
16%7%24333446%43%
1879
16th to endDay
17%425%433346%45%
1803
November1st to 15thDay
19%6%23313435%45%
1581
16th to endDay
14%6%25%425%446%44%
1595
December1st to 15thDay
16%5%35%4245%5%6%39%
1440
16th to endDay
21%8%33423446%37%
1536
January1st to 15thNight
17%425%424346%44%
2506
16th to endNight
15%8%33423347%42%
2621
February1st to 15thNight
14%9%35%424436%40%
2202
16th to endNight
17%5%23424446%44%
1893
March1st to 15thNight
18%6%24424446%42%
2147
16th to endNight
16%7%24423346%44%
1995
April1st to 15thNight
17%7%244335%46%40%
1796
16th to endNight
19%5%25%5%23337%42%
1762
May1st to 15thNight
18%6%35%424446%37%
1608
16th to endNight
18%6%245%2445%7%38%
1495
June1st to 15thNight
19%6%3441336%6%39%
1440
16th to endNight
9%325%435%5%6%9%44%
1440
July1st to 15thNight
11%435%6%25%6%7%10%38%
1440
16th to endNight
9%5%24435%5%8%9%40%
1514
August1st to 15thNight
9%4244345%6%7%46%
1626
16th to endNight
12%42443446%7%44%
1910
September1st to 15thNight
14%4244245%5%6%46%
1809
16th to endNight
13%5%25%5%22345%49%
1980
October1st to 15thNight
16%7%25%5%23335%45%
2079
16th to endNight
18%5%24424336%44%
2419
November1st to 15thNight
17%5%14423345%46%
2277
16th to endNight
16%6%25%423447%41%
2364
December1st to 15thNight
20%5%25%42435%7%37%
2520
16th to endNight
19%6%25%42445%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%6%3443445%7%41%
1432
16th to endDay
14%6%26%33445%6%41%
1602
February1st to 15thDay
15%6%26%5%24446%41%
1657
16th to endDay
15%425%435%346%44%
1580
March1st to 15thDay
17%6%34434448%38%
1800
16th to endDay
18%6%24423445%44%
2226
April1st to 15thDay
17%6%2443335%6%42%
2152
16th to endDay
16%5%14335%446%46%
2196
May1st to 15thDay
19%6%25%32345%8%37%
2352
16th to endDay
16%5%244245%5%9%40%
2618
June1st to 15thDay
18%5%2442445%8%38%
2520
16th to endDay
10%5%24435%5%5%9%43%
2520
July1st to 15thDay
9%4245%26%5%7%8%42%
2520
16th to endDay
11%5%25%435%46%9%41%
2654
August1st to 15thDay
11%414435%5%7%9%42%
2317
16th to endDay
11%4245%2446%8%46%
2292
September1st to 15thDay
11%42433445%7%47%
2151
16th to endDay
13%5%24424346%46%
1980
October1st to 15thDay
17%7%23324446%43%
1879
16th to endDay
17%414434346%44%
1803
November1st to 15thDay
19%5%23322446%45%
1581
16th to endDay
14%5%25%424446%44%
1595
December1st to 15thDay
16%5%35%425%45%7%39%
1440
16th to endDay
20%8%24324347%37%
1536
January1st to 15thNight
17%5%25%323346%43%
2506
16th to endNight
16%8%3432335%6%41%
2621
February1st to 15thNight
14%9%345%24446%41%
2195
16th to endNight
17%5%235%2435%5%44%
1893
March1st to 15thNight
18%6%24424446%42%
2160
16th to endNight
16%7%34422345%45%
1994
April1st to 15thNight
17%7%34424446%40%
1796
16th to endNight
18%5%25%5%23336%42%
1762
May1st to 15thNight
19%6%25%424446%37%
1608
16th to endNight
18%6%24425%45%7%38%
1495
June1st to 15thNight
19%5%3442435%8%38%
1440
16th to endNight
9%425%5%25%6%5%8%44%
1440
July1st to 15thNight
11%425%4345%8%9%38%
1440
16th to endNight
9%5%345%25%6%8%10%39%
1514
August1st to 15thNight
10%4145%3447%8%46%
1626
16th to endNight
13%4145%25%46%7%44%
1910
September1st to 15thNight
14%4144245%5%5%46%
1809
16th to endNight
13%5%25%5%12346%48%
1980
October1st to 15thNight
16%7%26%423335%45%
2079
16th to endNight
18%5%24423346%44%
2419
November1st to 15thNight
17%5%24423335%46%
2277
16th to endNight
16%6%25%32335%6%41%
2364
December1st to 15thNight
19%6%2442435%7%37%
2520
16th to endNight
19%7%25%42445%6%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
42%413%24%11%3
1433
16th to endDay
42%311%25%13%2
1602
February1st to 15thDay
43%413%21%14%1
1660
16th to endDay
41%410%26%14%1
1580
March1st to 15thDay
44%5%14%22%11%1
1800
16th to endDay
43%410%21%17%3
2226
April1st to 15thDay
44%48%22%16%3
2152
16th to endDay
38%6%8%22%19%3
2196
May1st to 15thDay
45%6%9%20%15%1
2352
16th to endDay
40%7%16%20%12%2
2622
June1st to 15thDay
45%5%13%22%12%1
2520
16th to endDay
37%8%14%24%13%1
2520
July1st to 15thDay
37%8%12%22%17%1
2371
16th to endDay
37%7%15%23%13%2
2487
August1st to 15thDay
36%8%14%22%16%
2303
16th to endDay
35%6%11%24%19%1
2292
September1st to 15thDay
36%5%12%22%21%1
2151
16th to endDay
39%5%7%22%23%2
1980
October1st to 15thDay
41%6%10%21%18%1
1879
16th to endDay
41%310%24%17%2
1803
November1st to 15thDay
41%312%20%19%2
1581
16th to endDay
40%412%25%14%2
1595
December1st to 15thDay
42%6%15%19%13%
1440
16th to endDay
47%413%20%12%
1536
January1st to 15thNight
42%412%23%13%2
2506
16th to endNight
42%411%24%15%2
2621
February1st to 15thNight
44%5%11%23%12%2
2203
16th to endNight
41%38%25%18%2
1893
March1st to 15thNight
43%413%20%13%3
2160
16th to endNight
41%39%22%17%4
1995
April1st to 15thNight
45%5%10%19%16%2
1796
16th to endNight
44%48%17%21%3
1762
May1st to 15thNight
47%5%10%18%15%3
1608
16th to endNight
44%6%15%18%13%1
1497
June1st to 15thNight
44%6%12%20%15%1
1440
16th to endNight
36%6%14%26%14%1
1440
July1st to 15thNight
39%8%13%21%14%1
1360
16th to endNight
35%8%16%24%12%2
1418
August1st to 15thNight
34%6%14%26%15%1
1616
16th to endNight
36%6%14%23%17%1
1910
September1st to 15thNight
37%6%10%26%17%1
1809
16th to endNight
38%5%6%22%25%2
1980
October1st to 15thNight
43%410%23%16%2
2079
16th to endNight
40%313%25%16%1
2419
November1st to 15thNight
41%49%21%19%3
2277
16th to endNight
42%411%26%12%2
2364
December1st to 15thNight
45%415%20%13%
2520
16th to endNight
46%5%12%21%12%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
16%21%33%26%1
60
16th to endDay
18%13%45%20%2
75
February1st to 15thDay
20%15%42%19%1
173
16th to endDay
17%16%36%22%7%
239
March1st to 15thDay
19%15%38%20%5%
270
16th to endDay
21%13%38%19%42
288
April1st to 15thDay
22%10%32%20%11%1
270
16th to endDay
22%8%31%24%10%1
270
May1st to 15thDay
28%12%27%21%7%2
288
16th to endDay
19%323%31%20%1
331
June1st to 15thDay
22%6%23%28%17%1
315
16th to endDay
15%130%33%15%1
315
July1st to 15thDay
13%123%39%20%2
305
16th to endDay
14%220%33%23%6%
326
August1st to 15thDay
14%218%34%23%5%
313
16th to endDay
12%315%40%21%8%
332
September1st to 15thDay
14%328%23%21%7%
315
16th to endDay
19%318%27%20%11%
314
October1st to 15thDay
24%5%20%26%17%6%
315
16th to endDay
15%13%30%26%12%
307
November1st to 15thDay
22%11%25%25%12%2
235
16th to endDay
14%17%31%25%9%1
215
December1st to 15thDay
15%20%38%20%6%
60
16th to endDay
34%12%43%9%
64
January1st to 15thNight
19%18%36%21%3
720
16th to endNight
21%17%39%20%1
768
February1st to 15thNight
18%16%42%20%1
704
16th to endNight
19%19%36%22%3
631
March1st to 15thNight
22%14%38%19%5%
720
16th to endNight
19%14%38%20%5%
768
April1st to 15thNight
21%12%34%26%5%
718
16th to endNight
21%8%34%27%7%
682
May1st to 15thNight
21%7%36%26%7%
528
16th to endNight
22%5%22%35%12%1
375
June1st to 15thNight
21%5%20%35%16%
360
16th to endNight
10%221%49%14%
360
July1st to 15thNight
12%224%44%15%1
340
16th to endNight
10%319%44%19%1
376
August1st to 15thNight
12%121%42%19%1
545
16th to endNight
13%315%37%28%2
764
September1st to 15thNight
16%424%33%17%2
720
16th to endNight
17%220%28%24%5%
717
October1st to 15thNight
19%8%28%26%14%2
720
16th to endNight
21%11%32%25%8%
768
November1st to 15thNight
19%12%32%23%11%1
700
16th to endNight
19%15%32%22%9%1
720
December1st to 15thNight
23%15%34%19%5%1
720
16th to endNight
23%16%40%17%2
768
Page generated at 2017-11-01 17:23:29. Version ac04

Copyright 2017 A. Danko


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