Weeksville
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Weeksville clear sky chart from 2005-11-06 to 2024-01-17.

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
41%
23938
20%
74681
12%
23888
50%
23888
25%
47026

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 10thNight
24%
757
21%
2530
8%
757
40%
757
19%
1574
January11th to 20thNight
28%
748
22%
2430
10%
748
43%
748
19%
1599
January21st to endNight
23%
792
25%
2574
10%
792
43%
792
23%
1571
February1st to 10thNight
27%
720
20%
2340
11%
720
41%
720
22%
1468
February11th to 20thNight
17%
702
19%
2100
7%
700
33%
700
19%
1395
February21st to endNight
24%
592
26%
1776
13%
592
40%
592
23%
1117
March1st to 10thNight
27%
720
23%
2056
11%
720
41%
720
29%
1258
March11th to 20thNight
24%
720
18%
1980
8%
720
35%
720
23%
1348
March21st to endNight
29%
792
21%
2106
10%
792
38%
792
26%
1413
April1st to 10thNight
29%
720
21%
1800
6%
720
39%
720
29%
1193
April11th to 20thNight
35%
711
24%
1775
9%
711
42%
711
33%
1153
April21st to endNight
36%
720
22%
1800
9%
720
41%
720
32%
1182
May1st to 10thNight
36%
720
16%
1800
6%
720
40%
720
28%
1217
May11th to 20thNight
46%
546
16%
1608
9%
546
51%
546
25%
1068
May21st to endNight
63%
388
18%
1551
20%
388
65%
388
24%
895
June1st to 10thNight
57%
360
17%
1440
18%
360
61%
360
23%
853
June11th to 20thNight
62%
360
14%
1440
16%
360
64%
360
21%
869
June21st to endNight
65%
360
16%
1440
20%
360
67%
360
22%
871
July1st to 10thNight
68%
350
15%
1400
16%
350
70%
350
20%
875
July11th to 20thNight
73%
498
13%
1542
12%
498
74%
498
29%
974
July21st to endNight
65%
591
14%
1672
11%
558
68%
558
25%
1122
August1st to 10thNight
60%
569
11%
1632
8%
566
61%
566
25%
1094
August11th to 20thNight
61%
710
14%
1774
8%
710
62%
710
28%
1238
August21st to endNight
60%
792
15%
1980
9%
792
61%
792
27%
1392
September1st to 10thNight
61%
720
19%
1800
13%
720
63%
720
29%
1232
September11th to 20thNight
56%
720
23%
1800
16%
720
59%
720
30%
1238
September21st to endNight
46%
720
17%
2014
13%
720
52%
720
21%
1432
October1st to 10thNight
52%
720
22%
2160
19%
720
58%
720
29%
1336
October11th to 20thNight
45%
720
26%
2160
20%
720
55%
720
30%
1303
October21st to endNight
46%
792
30%
2376
21%
792
58%
792
34%
1365
November1st to 10thNight
44%
740
24%
2297
18%
740
53%
740
28%
1410
November11th to 20thNight
37%
760
23%
2470
15%
760
49%
760
24%
1525
November21st to endNight
40%
760
26%
2470
18%
760
52%
760
29%
1422
December1st to 10thNight
28%
760
19%
2657
8%
760
44%
760
18%
1720
December11th to 20thNight
32%
760
22%
3181
13%
759
46%
759
20%
1849
December21st to endNight
32%
828
15%
4750
11%
817
47%
817
14%
2455

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%6%9%43%
74706
Night
13%6%35%5%345%6%8%44%
75117
TransparencyDay
38%8%13%22%16%3
74420
Night
39%6%12%22%17%4
74922
SeeingDay
15%10%26%26%17%5%
14235
Night
16%9%27%31%15%2
23951

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 10thDay
12%6%35%5%33447%48%
1634
11th to 20thDay
16%6%244245%5%7%45%
1674
21st to endDay
15%7%345%34446%45%
1782
February1st to 10thDay
14%7%25%5%245%6%7%41%
1620
11th to 20thDay
18%7%34434446%45%
1747
21st to endDay
16%7%26%5%35%45%7%42%
1480
March1st to 10thDay
12%5%345%33346%52%
1901
11th to 20thDay
16%6%35%6%34447%43%
1980
21st to endDay
15%5%35%5%3436%7%43%
2249
April1st to 10thDay
12%425%42345%8%53%
2160
11th to 20thDay
8%5%2443446%8%51%
2134
21st to endDay
10%4245%35%5%6%7%48%
2160
May1st to 10thDay
11%425%5%46%5%6%10%41%
2160
11th to 20thDay
13%6%36%5%35%46%9%40%
2296
21st to endDay
10%5%35%5%35%6%6%9%43%
2725
June1st to 10thDay
10%4245%46%6%8%11%40%
2520
11th to 20thDay
9%5%24436%6%9%11%39%
2520
21st to endDay
7%436%7%46%7%8%12%38%
2520
July1st to 10thDay
8%5%35%5%46%6%8%12%39%
2520
11th to 20thDay
8%5%25%6%36%6%10%12%37%
2360
21st to endDay
7%5%25%6%47%7%9%12%35%
2547
August1st to 10thDay
11%6%36%6%5%5%6%8%11%34%
2275
11th to 20thDay
10%7%26%6%45%6%7%11%36%
2126
21st to endDay
10%6%25%6%46%7%7%11%36%
2376
September1st to 10thDay
11%5%26%6%35%6%6%9%40%
2160
11th to 20thDay
12%6%36%5%35%46%9%40%
2160
21st to endDay
18%7%36%5%345%6%8%34%
1939
October1st to 10thDay
15%7%35%434347%46%
1800
11th to 20thDay
12%5%36%5%3445%6%49%
1800
21st to endDay
12%5%25%6%34445%50%
1980
November1st to 10thDay
16%6%2443445%7%47%
1779
11th to 20thDay
15%6%2431345%7%50%
1710
21st to endDay
14%5%2442445%8%48%
1710
December1st to 10thDay
16%6%35%6%3446%7%41%
1520
11th to 20thDay
15%6%24423336%53%
1910
21st to endDay
15%6%25%5%24447%45%
2772
January1st to 10thNight
14%7%25%5%345%46%45%
2530
11th to 20thNight
13%7%36%6%345%6%7%38%
2430
21st to endNight
15%6%25%424445%47%
2574
February1st to 10thNight
18%7%3442446%7%41%
2340
11th to 20thNight
19%7%35%43345%6%41%
2098
21st to endNight
15%7%35%434346%46%
1776
March1st to 10thNight
14%5%2442445%5%51%
2056
11th to 20thNight
15%9%35%6%35%447%40%
1980
21st to endNight
14%5%36%5%35%5%6%7%42%
2106
April1st to 10thNight
13%5%25%425%5%5%6%47%
1800
11th to 20thNight
10%6%35%5%345%5%6%47%
1775
21st to endNight
12%5%35%5%235%5%6%49%
1800
May1st to 10thNight
12%6%35%4345%6%9%43%
1800
11th to 20thNight
14%7%24435%5%6%9%40%
1607
21st to endNight
9%6%346%345%7%11%43%
1550
June1st to 10thNight
11%5%35%5%345%7%9%43%
1440
11th to 20thNight
8%435%5%46%7%8%12%38%
1440
21st to endNight
9%325%6%36%7%8%11%41%
1440
July1st to 10thNight
7%436%6%47%7%9%13%36%
1440
11th to 20thNight
7%426%6%37%5%8%11%41%
1594
21st to endNight
8%5%35%5%47%8%8%11%37%
1771
August1st to 10thNight
11%6%35%6%47%5%7%9%39%
1643
11th to 20thNight
8%6%37%7%46%5%7%10%37%
1774
21st to endNight
13%6%36%6%35%5%7%10%36%
1980
September1st to 10thNight
11%5%36%5%35%6%6%8%42%
1800
11th to 20thNight
13%7%35%6%345%5%8%42%
1800
21st to endNight
18%7%36%6%45%45%7%35%
2014
October1st to 10thNight
13%425%5%245%5%7%47%
2160
11th to 20thNight
13%5%25%423347%50%
2160
21st to endNight
12%5%2442345%7%52%
2376
November1st to 10thNight
15%6%24434346%48%
2297
11th to 20thNight
16%6%2443445%6%46%
2470
21st to endNight
12%5%25%423448%50%
2470
December1st to 10thNight
16%7%36%435%5%5%6%40%
2657
11th to 20thNight
17%6%2442445%6%46%
3285
21st to endNight
13%6%25%43445%7%46%
4884

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 10thDay
37%5%10%25%19%5%
1635
11th to 20thDay
39%6%11%21%20%4
1674
21st to endDay
41%48%22%21%4
1782
February1st to 10thDay
42%411%25%15%4
1620
11th to 20thDay
43%49%17%21%6%
1756
21st to endDay
43%5%12%19%15%6%
1480
March1st to 10thDay
34%5%10%25%21%5%
1901
11th to 20thDay
42%5%10%21%16%6%
1980
21st to endDay
41%6%12%20%18%3
2249
April1st to 10thDay
32%5%12%23%22%5%
2160
11th to 20thDay
32%6%11%24%20%7%
2134
21st to endDay
35%7%13%24%18%4
2160
May1st to 10thDay
37%8%16%21%15%3
2160
11th to 20thDay
41%9%11%25%12%2
2300
21st to endDay
36%10%15%26%12%1
2725
June1st to 10thDay
36%11%14%24%13%1
2520
11th to 20thDay
35%11%18%23%12%1
2520
21st to endDay
35%13%17%22%11%2
2520
July1st to 10thDay
34%13%18%22%11%1
2450
11th to 20thDay
36%14%18%21%9%1
2289
21st to endDay
35%13%18%24%10%1
2405
August1st to 10thDay
40%12%21%18%8%
2262
11th to 20thDay
40%14%17%20%9%1
2126
21st to endDay
40%12%16%19%10%3
2376
September1st to 10thDay
39%11%16%18%14%2
2160
11th to 20thDay
41%9%10%20%18%2
2160
21st to endDay
47%8%12%19%14%2
1939
October1st to 10thDay
41%6%8%22%22%2
1800
11th to 20thDay
37%6%8%24%22%4
1800
21st to endDay
37%47%21%27%4
1980
November1st to 10thDay
39%5%11%19%22%4
1779
11th to 20thDay
35%5%10%23%21%6%
1710
21st to endDay
35%5%10%25%21%4
1710
December1st to 10thDay
44%7%11%21%15%3
1520
11th to 20thDay
37%37%27%18%7%
1906
21st to endDay
39%5%8%26%20%2
2772
January1st to 10thNight
41%5%8%22%19%5%
2530
11th to 20thNight
44%6%9%20%17%4
2430
21st to endNight
40%48%23%20%6%
2574
February1st to 10thNight
42%49%23%17%4
2340
11th to 20thNight
45%48%18%18%6%
2100
21st to endNight
40%48%21%20%7%
1776
March1st to 10thNight
35%5%12%24%19%5%
2056
11th to 20thNight
45%5%10%20%16%4
1980
21st to endNight
41%6%11%22%16%4
2106
April1st to 10thNight
38%6%11%18%23%5%
1800
11th to 20thNight
37%5%11%23%19%5%
1775
21st to endNight
37%6%11%26%18%3
1800
May1st to 10thNight
38%8%14%23%15%2
1800
11th to 20thNight
41%8%15%23%12%2
1608
21st to endNight
33%10%18%26%11%1
1551
June1st to 10thNight
36%9%16%27%12%1
1440
11th to 20thNight
35%12%20%21%12%1
1440
21st to endNight
35%12%18%22%12%1
1440
July1st to 10thNight
37%12%18%19%11%1
1400
11th to 20thNight
32%12%23%23%9%
1542
21st to endNight
36%14%18%24%7%1
1672
August1st to 10thNight
40%10%21%22%7%
1632
11th to 20thNight
41%9%21%19%10%1
1774
21st to endNight
42%9%17%21%9%2
1980
September1st to 10thNight
39%10%19%17%14%3
1800
11th to 20thNight
41%7%11%22%16%2
1800
21st to endNight
49%7%11%19%14%1
2014
October1st to 10thNight
37%6%10%22%22%4
2160
11th to 20thNight
35%5%10%22%23%4
2160
21st to endNight
33%48%23%26%6%
2376
November1st to 10thNight
38%5%8%21%24%4
2297
11th to 20thNight
40%49%17%22%7%
2470
21st to endNight
34%410%25%22%5%
2470
December1st to 10thNight
45%6%11%18%17%3
2657
11th to 20thNight
39%410%20%21%5%
3288
21st to endNight
37%5%12%24%20%2
4884

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 10thDay
18%22%40%16%3
236
11th to 20thDay
19%25%33%20%3
258
21st to endDay
20%21%37%17%41
264
February1st to 10thDay
20%18%41%17%4
240
11th to 20thDay
29%20%34%14%2
415
21st to endDay
20%21%33%22%31
346
March1st to 10thDay
16%22%34%22%5%
420
11th to 20thDay
24%16%35%17%5%2
420
21st to endDay
18%17%36%21%7%1
462
April1st to 10thDay
16%19%34%23%6%2
420
11th to 20thDay
11%17%33%24%10%4
412
21st to endDay
14%13%31%27%13%2
420
May1st to 10thDay
16%13%31%26%11%3
423
11th to 20thDay
16%6%26%33%15%4
447
21st to endDay
14%6%20%32%20%8%
485
June1st to 10thDay
12%324%30%25%6%
450
11th to 20thDay
11%5%21%29%23%10%
450
21st to endDay
7%419%36%28%6%
450
July1st to 10thDay
9%214%35%29%11%
445
11th to 20thDay
8%211%33%36%10%
444
21st to endDay
9%415%36%30%7%
488
August1st to 10thDay
14%315%32%27%9%
446
11th to 20thDay
13%112%29%29%15%
439
21st to endDay
12%315%31%28%11%
495
September1st to 10thDay
13%318%27%25%14%
450
11th to 20thDay
15%418%30%24%8%
450
21st to endDay
22%6%20%26%19%7%
450
October1st to 10thDay
19%7%21%24%20%8%
450
11th to 20thDay
14%10%27%26%18%4
450
21st to endDay
12%12%26%27%18%3
495
November1st to 10thDay
19%10%27%27%12%4
417
11th to 20thDay
17%15%31%26%11%1
370
21st to endDay
15%16%28%22%16%2
370
December1st to 10thDay
18%17%43%15%6%2
180
11th to 20thDay
18%18%33%20%10%1
180
21st to endDay
21%16%31%19%13%1
198
January1st to 10thNight
18%21%33%23%5%
760
11th to 20thNight
19%15%32%27%7%
748
21st to endNight
18%16%39%23%3
792
February1st to 10thNight
23%14%33%27%3
720
11th to 20thNight
24%18%38%18%2
703
21st to endNight
17%16%38%24%5%
592
March1st to 10thNight
16%15%40%23%6%
720
11th to 20thNight
20%13%40%21%7%
720
21st to endNight
18%14%35%28%5%
792
April1st to 10thNight
16%14%38%26%5%
720
11th to 20thNight
13%12%36%29%9%1
711
21st to endNight
15%8%37%34%6%1
720
May1st to 10thNight
14%11%34%32%9%
720
11th to 20thNight
16%7%25%38%13%1
546
21st to endNight
13%215%42%25%3
389
June1st to 10thNight
13%219%44%20%2
360
11th to 20thNight
9%317%45%23%3
360
21st to endNight
7%315%51%23%1
360
July1st to 10thNight
8%213%43%31%3
350
11th to 20thNight
8%18%40%36%7%
498
21st to endNight
9%214%43%28%4
591
August1st to 10thNight
13%212%37%32%4
569
11th to 20thNight
11%113%37%33%5%
710
21st to endNight
14%212%30%35%7%
792
September1st to 10thNight
12%214%31%31%9%
720
11th to 20thNight
17%314%36%27%4
720
21st to endNight
21%5%17%32%23%3
720
October1st to 10thNight
15%5%20%29%25%5%
720
11th to 20thNight
18%8%23%30%20%2
720
21st to endNight
14%9%27%29%18%3
792
November1st to 10thNight
19%8%23%32%14%5%
740
11th to 20thNight
20%11%28%29%11%1
760
21st to endNight
13%13%29%27%16%1
760
December1st to 10thNight
19%14%32%26%9%
760
11th to 20thNight
18%11%36%27%9%
760
21st to endNight
17%12%34%29%8%
836
Page generated at 2024-01-14 09:55:05. Version ac07

Copyright 2024 Attilla Danko


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