Dacula
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Dacula clear sky chart from 2005-11-05 to 2017-09-17.

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
48%
15531
23%
46940
15%
15488
56%
15488
28%
28921

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
25%
720
23%
2327
9%
716
41%
716
21%
1439
January16th to endNight
25%
768
25%
2466
11%
768
42%
768
22%
1530
February1st to 15thNight
29%
704
26%
2111
9%
701
46%
701
26%
1282
February16th to endNight
24%
631
25%
1893
8%
631
40%
631
24%
1176
March1st to 15thNight
32%
720
24%
2052
12%
720
42%
720
28%
1285
March16th to endNight
38%
768
22%
2112
12%
768
46%
768
30%
1309
April1st to 15thNight
42%
659
25%
1917
15%
659
52%
659
35%
1113
April16th to endNight
49%
540
25%
1687
16%
540
59%
540
33%
975
May1st to 15thNight
49%
540
20%
1620
11%
540
56%
540
29%
1005
May16th to endNight
61%
561
21%
1683
15%
561
65%
561
31%
1035
June1st to 15thNight
70%
540
17%
1620
15%
540
72%
540
30%
1014
June16th to endNight
75%
540
16%
1620
13%
540
77%
540
32%
986
July1st to 15thNight
71%
510
13%
1530
11%
510
71%
510
27%
994
July16th to endNight
75%
564
16%
1595
13%
531
77%
531
28%
1021
August1st to 15thNight
67%
539
18%
1615
18%
536
68%
536
26%
1070
August16th to endNight
65%
573
18%
1910
20%
573
66%
573
21%
1274
September1st to 15thNight
63%
717
20%
1977
18%
717
64%
717
27%
1336
September16th to endNight
58%
665
23%
1837
17%
665
63%
665
29%
1198
October1st to 15thNight
54%
660
32%
1834
25%
660
61%
660
36%
1096
October16th to endNight
52%
704
34%
2112
25%
704
65%
704
38%
1164
November1st to 15thNight
50%
700
31%
2246
26%
700
61%
700
37%
1208
November16th to endNight
40%
720
27%
2340
18%
720
54%
720
29%
1325
December1st to 15thNight
35%
720
24%
2340
15%
720
48%
720
25%
1426
December16th to endNight
31%
768
21%
2496
14%
768
42%
768
20%
1660

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
13%5%244345%5%7%42%
47832
Night
12%42442445%7%46%
47139
TransparencyDay
38%6%12%19%17%4
47533
Night
36%6%11%20%19%6%
46942
SeeingDay
15%6%18%22%22%12%
5403
Night
14%7%23%28%21%3
15533

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
16%6%35%41434444%
1611
16th to endDay
18%5%2432345%5%44%
1757
February1st to 15thDay
16%415%424445%45%
1750
16th to endDay
18%5%24323445%43%
1580
March1st to 15thDay
16%5%245%24347%44%
1908
16th to endDay
16%42442335%8%43%
2111
April1st to 15thDay
12%5%25%5%34446%46%
2040
16th to endDay
11%4144235%5%7%49%
2271
May1st to 15thDay
11%5%2442346%7%46%
2331
16th to endDay
10%4245%35%46%9%41%
2431
June1st to 15thDay
9%4246%45%6%8%11%35%
2340
16th to endDay
43135%36%6%8%10%44%
2340
July1st to 15thDay
10%5%25%5%5%6%8%8%10%31%
2340
16th to endDay
7%5%25%5%5%7%8%8%10%32%
2465
August1st to 15thDay
9%5%26%7%47%6%7%10%32%
2331
16th to endDay
13%7%27%5%46%6%6%10%28%
2283
September1st to 15thDay
12%5%25%5%45%5%7%7%37%
1980
16th to endDay
15%5%244345%5%7%41%
1829
October1st to 15thDay
12%41331324456%
1796
16th to endDay
11%41331233459%
1760
November1st to 15thDay
11%422223345%55%
1610
16th to endDay
15%5%14323336%49%
1620
December1st to 15thDay
19%6%25%5%2345%5%40%
1620
16th to endDay
23%8%35%42333437%
1728
January1st to 15thNight
18%6%24324345%45%
2327
16th to endNight
17%6%24423346%44%
2466
February1st to 15thNight
15%424423246%49%
2103
16th to endNight
17%414423346%46%
1893
March1st to 15thNight
13%5%24423445%47%
2052
16th to endNight
12%5%1432345%6%48%
2112
April1st to 15thNight
12%41332345%7%51%
1917
16th to endNight
9%425%32345%7%50%
1687
May1st to 15thNight
10%4245%25%5%5%8%46%
1619
16th to endNight
7%4145%345%6%7%48%
1682
June1st to 15thNight
6%324445%6%8%11%41%
1620
16th to endNight
5%2145%36%7%10%10%42%
1620
July1st to 15thNight
7%425%6%36%6%8%11%35%
1620
16th to endNight
5%3245%47%7%9%14%34%
1703
August1st to 15thNight
8%5%25%6%346%7%11%37%
1626
16th to endNight
12%5%25%5%45%6%7%9%35%
1910
September1st to 15thNight
9%426%6%36%5%5%8%41%
1977
16th to endNight
14%4135%2445%7%44%
1837
October1st to 15thNight
11%414313346%53%
1834
16th to endNight
10%32332333360%
2112
November1st to 15thNight
11%312323245%58%
2246
16th to endNight
15%5%13323345%52%
2340
December1st to 15thNight
15%5%25%413347%45%
2340
16th to endNight
21%7%24433346%37%
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
41%410%15%24%4
1612
16th to endDay
40%36%20%21%7%
1757
February1st to 15thDay
39%48%20%23%3
1752
16th to endDay
41%47%20%19%6%
1580
March1st to 15thDay
39%410%19%20%5%
1908
16th to endDay
40%5%12%21%16%3
2112
April1st to 15thDay
38%49%21%20%5%
2040
16th to endDay
32%6%10%22%23%4
2271
May1st to 15thDay
35%6%14%21%19%2
2331
16th to endDay
36%9%14%24%13%2
2435
June1st to 15thDay
37%10%19%23%7%1
2340
16th to endDay
30%9%17%25%14%2
2340
July1st to 15thDay
39%12%19%19%6%1
2201
16th to endDay
41%12%17%18%8%1
2310
August1st to 15thDay
43%11%15%18%9%1
2318
16th to endDay
48%10%15%14%10%
2283
September1st to 15thDay
42%9%13%17%14%2
1980
16th to endDay
41%5%11%17%18%4
1829
October1st to 15thDay
31%410%18%27%7%
1796
16th to endDay
29%36%18%31%11%
1760
November1st to 15thDay
30%47%15%31%10%
1610
16th to endDay
36%46%17%27%7%
1620
December1st to 15thDay
43%48%19%14%8%
1620
16th to endDay
51%28%17%13%6%
1728
January1st to 15thNight
41%27%18%23%5%
2327
16th to endNight
41%35%18%23%7%
2466
February1st to 15thNight
37%37%20%21%9%
2112
16th to endNight
39%36%21%23%6%
1893
March1st to 15thNight
37%5%9%18%20%8%
2052
16th to endNight
35%5%10%22%21%5%
2112
April1st to 15thNight
30%410%23%22%7%
1917
16th to endNight
32%5%10%22%21%8%
1687
May1st to 15thNight
35%8%14%19%19%3
1620
16th to endNight
32%8%13%26%15%3
1684
June1st to 15thNight
32%10%19%26%9%1
1620
16th to endNight
29%11%18%23%14%2
1620
July1st to 15thNight
34%12%21%21%7%2
1530
16th to endNight
33%11%23%19%8%2
1595
August1st to 15thNight
37%10%16%22%11%1
1615
16th to endNight
41%10%17%17%11%
1910
September1st to 15thNight
38%9%12%18%15%3
1977
16th to endNight
37%8%12%18%17%5%
1837
October1st to 15thNight
32%5%10%16%26%8%
1834
16th to endNight
28%3417%31%13%
2112
November1st to 15thNight
29%35%17%30%13%
2246
16th to endNight
34%36%18%26%10%
2340
December1st to 15thNight
39%48%21%17%8%
2340
16th to endNight
47%38%16%18%5%
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
18%15%40%18%5%1
90
16th to endDay
13%35%36%12%2
96
February1st to 15thDay
14%26%36%21%1
90
16th to endDay
23%18%43%11%3
81
March1st to 15thDay
18%14%33%21%10%1
198
16th to endDay
16%11%29%25%14%1
288
April1st to 15thDay
15%14%26%18%20%4
270
16th to endDay
13%8%22%29%22%2
270
May1st to 15thDay
14%9%28%17%17%12%
288
16th to endDay
15%318%23%23%15%
331
June1st to 15thDay
11%39%22%31%22%
315
16th to endDay
7%13%28%25%24%
315
July1st to 15thDay
10%18%24%30%25%
305
16th to endDay
8%6%18%39%26%
326
August1st to 15thDay
17%17%23%26%22%
313
16th to endDay
17%9%23%28%20%
332
September1st to 15thDay
13%312%22%30%17%
315
16th to endDay
20%213%24%28%11%
259
October1st to 15thDay
18%225%22%20%9%
255
16th to endDay
13%6%17%26%29%5%
272
November1st to 15thDay
27%14%21%17%16%2
118
16th to endDay
14%11%24%34%11%4
90
December1st to 15thDay
27%15%27%22%6%
90
16th to endDay
33%20%26%15%31
96
January1st to 15thNight
22%18%29%23%6%
720
16th to endNight
19%16%35%23%4
768
February1st to 15thNight
18%15%32%29%4
704
16th to endNight
18%18%35%24%3
631
March1st to 15thNight
17%12%34%29%5%
720
16th to endNight
15%11%28%30%13%
768
April1st to 15thNight
14%11%30%27%15%
659
16th to endNight
11%6%28%31%20%1
540
May1st to 15thNight
12%427%29%22%3
540
16th to endNight
10%117%31%33%5%
563
June1st to 15thNight
7%14%33%33%10%
540
16th to endNight
5%9%33%38%11%
540
July1st to 15thNight
9%15%25%45%12%
510
16th to endNight
5%7%26%49%10%
564
August1st to 15thNight
11%17%27%43%8%
539
16th to endNight
14%17%26%41%9%
573
September1st to 15thNight
11%110%25%41%9%
717
16th to endNight
18%113%34%29%2
665
October1st to 15thNight
15%421%27%25%5%
660
16th to endNight
11%6%23%30%24%3
704
November1st to 15thNight
12%6%25%30%22%1
700
16th to endNight
18%10%27%27%15%
720
December1st to 15thNight
17%10%31%28%11%
720
16th to endNight
24%12%28%29%6%
768
Page generated at 2017-09-18 08:38:19. Version ac04

Copyright 2017 A. Danko


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