Hampton Plantation State Historic Site
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Hampton Plantation State Historic Site clear sky chart from 2005-11-05 to 2019-06-02.

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
53%
18353
21%
53776
15%
18311
59%
18311
27%
34377

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
36%
839
21%
2717
12%
836
50%
836
20%
1728
January16th to endNight
35%
896
23%
2912
14%
896
49%
896
25%
1782
February1st to 15thNight
37%
824
20%
2674
13%
821
49%
821
24%
1650
February16th to endNight
37%
735
23%
2072
12%
735
48%
735
27%
1358
March1st to 15thNight
41%
840
25%
2310
15%
840
50%
840
31%
1461
March16th to endNight
45%
896
20%
2464
12%
896
53%
896
31%
1556
April1st to 15thNight
48%
838
23%
2191
14%
838
53%
838
34%
1387
April16th to endNight
53%
831
25%
2077
14%
831
57%
831
37%
1293
May1st to 15thNight
58%
699
22%
1960
14%
699
60%
699
35%
1187
May16th to endNight
66%
657
17%
1972
14%
657
68%
657
29%
1230
June1st to 15thNight
69%
588
13%
1765
12%
588
70%
588
26%
1164
June16th to endNight
72%
585
14%
1755
12%
585
74%
585
26%
1132
July1st to 15thNight
71%
555
14%
1665
13%
555
72%
555
25%
1081
July16th to endNight
70%
612
11%
1739
9%
579
72%
579
23%
1184
August1st to 15thNight
70%
575
12%
1715
11%
572
70%
572
22%
1174
August16th to endNight
66%
818
12%
2060
9%
818
66%
818
22%
1536
September1st to 15thNight
68%
780
17%
2034
14%
780
69%
780
27%
1437
September16th to endNight
59%
777
14%
2145
14%
777
60%
777
22%
1540
October1st to 15thNight
56%
780
27%
2340
27%
780
62%
780
31%
1428
October16th to endNight
56%
832
32%
2496
26%
832
67%
832
35%
1414
November1st to 15thNight
53%
820
27%
2461
21%
820
62%
820
34%
1434
November16th to endNight
48%
840
25%
2610
18%
840
58%
840
30%
1541
December1st to 15thNight
38%
840
21%
2730
15%
840
48%
840
21%
1760
December16th to endNight
39%
896
20%
2912
14%
896
47%
896
21%
1920

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
11%5%25%5%35%5%6%8%41%
54556
Night
10%5%25%5%3445%8%43%
53973
TransparencyDay
37%9%14%19%14%4
54257
Night
36%8%13%19%15%5%
53776
SeeingDay
13%419%27%26%10%
8127
Night
13%5%20%30%24%5%
18357

By Month

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
14%6%2443325%6%44%
1881
16th to endDay
13%5%36%424436%46%
2016
February1st to 15thDay
15%6%25%43345%5%43%
1845
16th to endDay
13%6%26%423445%45%
1972
March1st to 15thDay
11%5%2442345%7%47%
2310
16th to endDay
12%435%4345%5%6%45%
2463
April1st to 15thDay
11%42332345%7%51%
2417
16th to endDay
7%313325%5%6%8%51%
2488
May1st to 15thDay
8%4244346%6%8%46%
2661
16th to endDay
9%5%345%25%5%8%8%39%
2847
June1st to 15thDay
8%3246%36%8%9%11%34%
2548
16th to endDay
6%325%5%37%7%9%11%36%
2535
July1st to 15thDay
7%425%7%46%8%8%11%32%
2535
16th to endDay
8%5%25%7%5%7%7%8%12%29%
2673
August1st to 15thDay
9%5%35%7%47%7%9%12%27%
2484
16th to endDay
11%7%36%6%47%7%9%11%24%
2484
September1st to 15thDay
13%424446%7%7%10%35%
2252
16th to endDay
15%7%36%6%25%5%5%7%33%
2144
October1st to 15thDay
13%41341335%7%49%
1950
16th to endDay
9%424423336%56%
2080
November1st to 15thDay
11%5%23414246%52%
2057
16th to endDay
11%5%14413335%53%
2008
December1st to 15thDay
15%6%25%5%2445%5%41%
1890
16th to endDay
14%7%25%434445%44%
2016
January1st to 15thNight
10%6%35%5%35%445%44%
2717
16th to endNight
13%5%25%424446%46%
2912
February1st to 15thNight
15%5%24423447%45%
2665
16th to endNight
11%6%35%5%3445%6%42%
2072
March1st to 15thNight
9%425%5%2445%7%47%
2310
16th to endNight
10%425%42445%8%46%
2464
April1st to 15thNight
10%42442445%7%48%
2191
16th to endNight
8%42442445%8%50%
2077
May1st to 15thNight
7%5%145%2445%8%50%
1959
16th to endNight
8%425%42446%10%44%
1970
June1st to 15thNight
7%5%25%436%5%9%13%38%
1765
16th to endNight
44345%26%7%9%14%37%
1755
July1st to 15thNight
5%5%346%35%6%8%12%37%
1755
16th to endNight
6%435%6%47%6%8%12%35%
1847
August1st to 15thNight
7%5%25%6%36%6%9%15%31%
1726
16th to endNight
10%5%36%6%5%6%6%8%12%29%
2060
September1st to 15thNight
10%4246%445%8%12%37%
2034
16th to endNight
14%7%25%5%45%6%6%9%33%
2145
October1st to 15thNight
11%425%424347%49%
2340
16th to endNight
8%423324346%56%
2496
November1st to 15thNight
9%424423346%54%
2461
16th to endNight
10%5%2432435%6%51%
2610
December1st to 15thNight
16%5%25%42435%6%42%
2730
16th to endNight
14%7%345%245%46%40%
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
40%5%9%16%21%5%
1882
16th to endDay
39%39%19%21%6%
2016
February1st to 15thDay
41%5%8%18%19%5%
1847
16th to endDay
40%5%8%21%18%5%
1972
March1st to 15thDay
36%5%10%19%18%9%
2310
16th to endDay
37%7%14%19%17%5%
2464
April1st to 15thDay
31%6%12%24%18%5%
2417
16th to endDay
27%7%13%23%20%7%
2488
May1st to 15thDay
31%8%16%23%17%2
2661
16th to endDay
35%10%17%23%12%
2851
June1st to 15thDay
35%12%20%20%9%
2548
16th to endDay
34%13%22%22%5%
2535
July1st to 15thDay
35%15%20%20%6%1
2396
16th to endDay
38%16%21%17%4
2518
August1st to 15thDay
41%14%22%17%3
2471
16th to endDay
45%16%20%13%3
2484
September1st to 15thDay
37%14%17%14%12%2
2252
16th to endDay
45%11%13%16%10%2
2144
October1st to 15thDay
33%7%12%20%21%4
1950
16th to endDay
29%49%18%26%10%
2080
November1st to 15thDay
33%5%10%18%22%9%
2057
16th to endDay
33%5%9%18%22%9%
2008
December1st to 15thDay
42%6%11%17%14%6%
1890
16th to endDay
41%6%11%19%15%5%
2016
January1st to 15thNight
40%6%8%17%19%7%
2717
16th to endNight
38%5%7%18%21%9%
2912
February1st to 15thNight
39%49%17%18%9%
2674
16th to endNight
40%5%10%18%17%7%
2072
March1st to 15thNight
35%6%11%19%18%8%
2310
16th to endNight
34%7%14%19%16%6%
2464
April1st to 15thNight
34%5%13%20%18%7%
2191
16th to endNight
30%6%11%22%20%8%
2077
May1st to 15thNight
30%7%14%24%19%3
1960
16th to endNight
33%10%16%26%12%1
1972
June1st to 15thNight
34%14%21%21%8%
1765
16th to endNight
32%14%21%24%6%
1755
July1st to 15thNight
33%14%21%21%7%
1665
16th to endNight
37%13%21%21%4
1739
August1st to 15thNight
36%15%22%18%5%
1715
16th to endNight
43%14%19%19%2
2060
September1st to 15thNight
38%12%18%16%11%2
2034
16th to endNight
44%10%14%17%10%2
2145
October1st to 15thNight
35%6%9%22%19%6%
2340
16th to endNight
29%5%8%18%25%12%
2496
November1st to 15thNight
32%410%17%23%11%
2461
16th to endNight
34%410%16%22%10%
2610
December1st to 15thNight
42%6%12%16%16%6%
2730
16th to endNight
43%6%9%19%13%6%
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
18%11%37%25%6%
180
16th to endDay
15%8%41%28%41
192
February1st to 15thDay
16%9%36%31%5%
180
16th to endDay
15%6%39%27%11%
291
March1st to 15thDay
12%9%38%27%11%
390
16th to endDay
12%7%36%26%15%1
416
April1st to 15thDay
14%8%27%26%18%4
390
16th to endDay
8%5%16%35%23%10%
379
May1st to 15thDay
8%324%30%25%7%
408
16th to endDay
15%110%27%30%15%
459
June1st to 15thDay
9%8%28%36%16%
379
16th to endDay
8%7%22%40%21%
375
July1st to 15thDay
6%421%50%16%
365
16th to endDay
8%15%23%45%15%
390
August1st to 15thDay
12%25%21%39%18%
358
16th to endDay
14%15%17%39%22%
396
September1st to 15thDay
16%15%25%33%18%
375
16th to endDay
17%210%25%33%11%
374
October1st to 15thDay
18%314%29%21%13%
375
16th to endDay
10%5%22%30%25%7%
400
November1st to 15thDay
19%7%20%28%20%4
385
16th to endDay
11%426%37%16%3
298
December1st to 15thDay
27%231%30%7%1
180
16th to endDay
20%7%33%29%9%
192
January1st to 15thNight
13%14%29%30%11%1
840
16th to endNight
16%10%33%31%7%
896
February1st to 15thNight
16%10%29%35%7%
824
16th to endNight
15%8%32%33%8%
735
March1st to 15thNight
11%7%34%34%11%
840
16th to endNight
12%6%28%32%17%1
896
April1st to 15thNight
12%7%27%31%19%2
838
16th to endNight
10%6%24%33%22%2
831
May1st to 15thNight
9%320%33%29%4
700
16th to endNight
9%112%26%35%12%
659
June1st to 15thNight
9%16%33%39%9%
588
16th to endNight
7%6%31%40%12%
585
July1st to 15thNight
7%8%27%47%9%
555
16th to endNight
8%429%48%8%
612
August1st to 15thNight
12%323%48%10%
575
16th to endNight
13%15%22%41%16%
818
September1st to 15thNight
12%16%24%43%10%
780
16th to endNight
19%19%25%34%9%
777
October1st to 15thNight
15%318%26%26%9%
780
16th to endNight
10%5%21%30%25%6%
832
November1st to 15thNight
13%6%22%33%20%3
820
16th to endNight
13%10%22%30%20%3
840
December1st to 15thNight
18%9%25%29%14%2
840
16th to endNight
18%8%28%31%12%1
896
Page generated at 2019-06-02 19:43:08. Version ac04

Copyright 2019 A. Danko


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