Givhans Ferry State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Givhans Ferry State Park clear sky chart from 2005-11-05 to 2017-09-16.

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
48%
15915
21%
46883
14%
15872
55%
15872
28%
29485

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
32%
720
22%
2327
12%
716
46%
716
22%
1430
January16th to endNight
29%
768
23%
2496
12%
768
43%
768
24%
1532
February1st to 15thNight
32%
704
22%
2236
10%
701
47%
701
24%
1381
February16th to endNight
29%
631
26%
1818
11%
631
44%
631
27%
1129
March1st to 15thNight
32%
720
27%
1980
15%
720
44%
720
32%
1221
March16th to endNight
38%
768
20%
2112
10%
768
46%
768
31%
1306
April1st to 15thNight
38%
718
24%
1914
14%
718
46%
718
35%
1164
April16th to endNight
42%
720
26%
1800
13%
720
48%
720
38%
1107
May1st to 15thNight
49%
542
21%
1623
12%
542
55%
542
32%
964
May16th to endNight
60%
561
19%
1684
13%
561
64%
561
32%
1020
June1st to 15thNight
65%
540
13%
1620
10%
540
66%
540
28%
1040
June16th to endNight
68%
540
13%
1620
10%
540
70%
540
27%
1042
July1st to 15thNight
68%
510
12%
1530
10%
510
69%
510
26%
1011
July16th to endNight
69%
564
10%
1595
8%
531
72%
531
24%
1082
August1st to 15thNight
72%
539
14%
1609
13%
536
72%
536
22%
1118
August16th to endNight
61%
717
14%
1863
12%
717
61%
717
21%
1394
September1st to 15thNight
66%
720
19%
1950
16%
720
67%
720
28%
1299
September16th to endNight
51%
661
12%
1826
10%
661
53%
661
21%
1305
October1st to 15thNight
52%
660
29%
1948
27%
660
59%
660
33%
1168
October16th to endNight
53%
704
32%
2112
26%
704
64%
704
37%
1170
November1st to 15thNight
51%
700
30%
2101
22%
700
63%
700
37%
1176
November16th to endNight
42%
720
26%
2283
18%
720
53%
720
30%
1332
December1st to 15thNight
41%
720
22%
2340
17%
720
49%
720
25%
1475
December16th to endNight
35%
768
22%
2496
15%
768
46%
768
20%
1619

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
12%5%25%5%35%5%5%7%39%
47873
Night
11%5%2442446%8%44%
47080
TransparencyDay
41%7%12%17%15%5%
47574
Night
36%7%12%19%16%7%
46883
SeeingDay
13%7%21%25%21%11%
5751
Night
13%7%23%31%20%3
15918

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
15%6%2442434445%
1611
16th to endDay
16%6%34423336%45%
1728
February1st to 15thDay
16%5%2432345%6%44%
1624
16th to endDay
14%6%24413345%49%
1655
March1st to 15thDay
14%5%23423346%49%
1980
16th to endDay
14%425%434336%45%
2111
April1st to 15thDay
11%423425%347%49%
2032
16th to endDay
9%4245%25%45%8%47%
2166
May1st to 15thDay
9%426%6%35%6%6%7%41%
2331
16th to endDay
10%5%36%6%46%5%7%7%36%
2431
June1st to 15thDay
11%426%6%47%7%9%9%30%
2340
16th to endDay
6%436%7%5%8%7%8%9%31%
2340
July1st to 15thDay
10%6%37%6%47%7%7%10%29%
2340
16th to endDay
9%5%37%6%6%8%8%8%9%24%
2465
August1st to 15thDay
10%5%36%9%5%8%7%8%9%24%
2340
16th to endDay
12%7%38%9%47%6%6%9%22%
2327
September1st to 15thDay
10%6%26%6%46%7%8%7%33%
2007
16th to endDay
19%7%37%7%45%5%5%6%28%
1824
October1st to 15thDay
15%424424346%48%
1680
16th to endDay
10%42442334455%
1760
November1st to 15thDay
11%5%14313235%56%
1757
16th to endDay
12%6%13324346%50%
1676
December1st to 15thDay
15%6%35%5%23435%43%
1620
16th to endDay
17%6%25%5%23446%42%
1728
January1st to 15thNight
11%7%25%5%25%35%5%46%
2327
16th to endNight
14%7%25%423345%46%
2496
February1st to 15thNight
16%5%13324435%47%
2227
16th to endNight
11%6%24434346%47%
1818
March1st to 15thNight
9%42442446%8%47%
1980
16th to endNight
11%5%23424348%48%
2112
April1st to 15thNight
11%32331335%7%51%
1914
16th to endNight
9%31442446%8%50%
1800
May1st to 15thNight
8%424425%46%8%48%
1622
16th to endNight
8%5%2442446%8%48%
1682
June1st to 15thNight
8%425%5%35%7%7%11%36%
1620
16th to endNight
5%4235%35%8%10%12%38%
1620
July1st to 15thNight
7%5%25%6%35%6%9%12%35%
1620
16th to endNight
5%336%7%37%6%9%12%32%
1703
August1st to 15thNight
6%5%26%5%46%7%9%12%32%
1620
16th to endNight
10%5%27%7%5%7%6%6%9%31%
1863
September1st to 15thNight
8%3245%35%5%7%11%40%
1950
16th to endNight
15%6%26%6%346%7%7%32%
1826
October1st to 15thNight
15%5%24222346%50%
1948
16th to endNight
9%41232335%5%57%
2112
November1st to 15thNight
10%423323246%56%
2101
16th to endNight
13%414324346%51%
2283
December1st to 15thNight
15%5%24424446%44%
2340
16th to endNight
17%5%36%423446%40%
2496

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%8%16%22%7%
1612
16th to endDay
41%37%18%21%8%
1728
February1st to 15thDay
40%5%5%19%21%8%
1626
16th to endDay
37%47%20%21%8%
1655
March1st to 15thDay
35%410%20%18%10%
1980
16th to endDay
39%5%9%19%18%7%
2112
April1st to 15thDay
33%5%9%22%21%7%
2032
16th to endDay
32%5%10%21%20%9%
2166
May1st to 15thDay
38%7%12%18%18%3
2331
16th to endDay
43%8%14%20%12%1
2435
June1st to 15thDay
43%11%19%17%7%
2340
16th to endDay
43%11%17%18%7%
2340
July1st to 15thDay
45%11%18%17%5%1
2201
16th to endDay
47%14%19%13%4
2310
August1st to 15thDay
50%11%16%16%5%
2327
16th to endDay
55%12%13%13%5%
2327
September1st to 15thDay
43%10%13%14%13%4
2007
16th to endDay
54%7%10%12%10%4
1824
October1st to 15thDay
36%311%17%21%9%
1680
16th to endDay
31%46%16%26%14%
1760
November1st to 15thDay
32%36%18%25%14%
1757
16th to endDay
34%48%19%21%11%
1676
December1st to 15thDay
42%5%9%18%16%7%
1620
16th to endDay
42%410%18%16%7%
1728
January1st to 15thNight
39%48%16%21%8%
2327
16th to endNight
39%46%16%23%9%
2496
February1st to 15thNight
39%37%18%19%11%
2236
16th to endNight
37%49%17%20%10%
1818
March1st to 15thNight
33%6%10%21%18%9%
1980
16th to endNight
34%5%14%19%17%8%
2112
April1st to 15thNight
32%5%10%21%21%9%
1914
16th to endNight
30%5%11%23%22%7%
1800
May1st to 15thNight
32%7%15%21%20%2
1623
16th to endNight
32%8%17%27%13%1
1684
June1st to 15thNight
36%10%23%21%8%
1620
16th to endNight
32%14%22%22%7%
1620
July1st to 15thNight
34%14%21%21%6%2
1530
16th to endNight
36%14%23%18%5%1
1595
August1st to 15thNight
36%16%19%20%6%
1609
16th to endNight
45%12%17%18%4
1863
September1st to 15thNight
34%12%17%18%12%3
1950
16th to endNight
46%9%13%15%11%3
1826
October1st to 15thNight
35%49%21%20%8%
1948
16th to endNight
28%49%18%24%15%
2112
November1st to 15thNight
30%36%18%24%15%
2101
16th to endNight
34%49%15%22%13%
2283
December1st to 15thNight
39%5%11%17%16%8%
2340
16th to endNight
44%5%8%18%15%7%
2496

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
17%17%41%14%6%2
90
16th to endDay
15%29%36%17%1
96
February1st to 15thDay
16%25%46%10%1
90
16th to endDay
14%20%43%17%4
156
March1st to 15thDay
12%14%37%23%11%
270
16th to endDay
12%12%34%21%14%3
288
April1st to 15thDay
14%14%24%22%18%5%
270
16th to endDay
7%431%25%17%13%
270
May1st to 15thDay
6%13%28%21%20%8%
288
16th to endDay
11%321%25%20%18%
331
June1st to 15thDay
12%115%26%27%17%
315
16th to endDay
10%212%27%28%18%
315
July1st to 15thDay
7%11%31%33%15%
305
16th to endDay
9%19%29%35%15%
326
August1st to 15thDay
13%18%28%27%20%
313
16th to endDay
14%28%23%28%23%
332
September1st to 15thDay
14%113%25%26%17%
315
16th to endDay
24%14%24%26%9%
257
October1st to 15thDay
21%322%24%18%9%
255
16th to endDay
12%420%28%23%9%
272
November1st to 15thDay
16%9%22%26%23%1
265
16th to endDay
11%8%30%32%13%4
146
December1st to 15thDay
15%17%40%15%7%3
90
16th to endDay
23%13%25%32%41
96
January1st to 15thNight
13%15%32%27%10%
720
16th to endNight
18%13%34%27%4
768
February1st to 15thNight
18%15%30%30%5%
704
16th to endNight
15%12%37%28%6%
631
March1st to 15thNight
12%11%39%28%7%
720
16th to endNight
13%11%31%32%10%
768
April1st to 15thNight
12%11%33%29%10%1
718
16th to endNight
11%10%31%31%14%1
720
May1st to 15thNight
7%5%30%38%17%1
543
16th to endNight
10%217%35%29%4
563
June1st to 15thNight
10%112%39%30%5%
540
16th to endNight
5%112%35%35%8%
540
July1st to 15thNight
8%29%39%35%4
510
16th to endNight
6%15%38%41%6%
564
August1st to 15thNight
9%15%33%41%8%
539
16th to endNight
12%19%28%36%11%
717
September1st to 15thNight
9%110%35%37%6%
720
16th to endNight
19%214%31%26%5%
661
October1st to 15thNight
18%319%29%24%4
660
16th to endNight
11%6%23%30%24%3
704
November1st to 15thNight
12%7%23%35%18%2
700
16th to endNight
14%10%29%25%18%2
720
December1st to 15thNight
17%8%27%30%14%1
720
16th to endNight
17%11%30%30%9%
768
Page generated at 2017-09-17 12:05:48. Version ac04

Copyright 2017 A. Danko


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