Dallas(GA)
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Dallas(GA) 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
45%
15431
24%
46927
15%
15388
55%
15388
28%
28552

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
23%
720
24%
2327
8%
716
42%
716
19%
1457
January16th to endNight
24%
768
25%
2418
11%
768
40%
768
19%
1538
February1st to 15thNight
24%
704
25%
2111
8%
701
40%
701
24%
1307
February16th to endNight
19%
631
24%
1893
8%
631
34%
631
22%
1195
March1st to 15thNight
28%
720
23%
2085
11%
720
39%
720
25%
1301
March16th to endNight
36%
768
22%
2112
12%
768
44%
768
28%
1328
April1st to 15thNight
39%
599
25%
1857
15%
599
51%
599
31%
1061
April16th to endNight
46%
540
26%
1728
17%
540
56%
540
32%
973
May1st to 15thNight
50%
540
22%
1620
12%
540
60%
540
31%
978
May16th to endNight
62%
561
23%
1682
17%
561
67%
561
35%
999
June1st to 15thNight
70%
540
17%
1620
14%
540
71%
540
34%
967
June16th to endNight
77%
540
18%
1620
15%
540
78%
540
39%
943
July1st to 15thNight
70%
510
16%
1530
13%
510
72%
510
30%
960
July16th to endNight
70%
564
17%
1595
15%
531
71%
531
29%
1001
August1st to 15thNight
73%
539
20%
1681
21%
536
73%
536
31%
1021
August16th to endNight
66%
573
20%
1910
22%
573
67%
573
24%
1231
September1st to 15thNight
63%
684
20%
1944
19%
684
64%
684
30%
1242
September16th to endNight
57%
658
24%
1818
17%
658
63%
658
31%
1138
October1st to 15thNight
51%
660
34%
1815
24%
660
60%
660
40%
1045
October16th to endNight
48%
704
33%
2109
25%
704
61%
704
36%
1172
November1st to 15thNight
46%
700
31%
2276
23%
700
59%
700
33%
1228
November16th to endNight
36%
720
28%
2340
17%
720
51%
720
28%
1344
December1st to 15thNight
30%
720
23%
2340
12%
720
44%
720
23%
1450
December16th to endNight
27%
768
20%
2496
12%
768
38%
768
18%
1673

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%40%
47808
Night
11%5%2442445%7%45%
47127
TransparencyDay
41%5%11%19%17%4
47509
Night
36%411%21%20%5%
46930
SeeingDay
14%7%20%23%20%13%
5320
Night
14%10%22%26%21%4
15433

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%8%24434336%43%
1611
16th to endDay
16%6%34424446%43%
1803
February1st to 15thDay
16%7%24424446%42%
1750
16th to endDay
17%6%244235%46%41%
1580
March1st to 15thDay
15%7%35%6%24347%40%
1874
16th to endDay
14%7%26%425%45%6%40%
2111
April1st to 15thDay
11%6%25%5%35%445%45%
2100
16th to endDay
11%4245%3445%7%47%
2232
May1st to 15thDay
9%6%35%5%345%5%7%42%
2331
16th to endDay
8%6%25%6%25%5%6%9%40%
2431
June1st to 15thDay
8%5%26%7%47%7%7%10%32%
2340
16th to endDay
5%3145%46%6%8%10%42%
2340
July1st to 15thDay
10%5%35%7%5%8%6%8%10%27%
2340
16th to endDay
6%336%8%48%7%9%10%29%
2465
August1st to 15thDay
7%5%146%5%7%7%9%11%31%
2265
16th to endDay
13%6%26%7%6%7%8%5%7%26%
2292
September1st to 15thDay
13%6%25%445%6%6%9%35%
2004
16th to endDay
16%5%2443345%6%41%
1815
October1st to 15thDay
14%423323336%51%
1815
16th to endDay
12%41431333457%
1759
November1st to 15thDay
13%5%2331244454%
1582
16th to endDay
14%5%14423435%49%
1620
December1st to 15thDay
16%6%25%5%24447%40%
1620
16th to endDay
22%8%45%42434435%
1728
January1st to 15thNight
17%7%23324436%43%
2327
16th to endNight
16%7%35%42335%5%42%
2418
February1st to 15thNight
13%5%34434337%45%
2103
16th to endNight
16%5%3441435%5%44%
1893
March1st to 15thNight
13%6%24424447%45%
2085
16th to endNight
11%6%245%24346%48%
2112
April1st to 15thNight
10%42342445%7%49%
1857
16th to endNight
10%42442345%8%50%
1728
May1st to 15thNight
8%325%5%25%5%5%8%46%
1619
16th to endNight
6%414435%5%6%9%47%
1682
June1st to 15thNight
43236%35%6%8%11%43%
1620
16th to endNight
42235%26%6%7%13%45%
1620
July1st to 15thNight
6%335%7%36%6%8%9%39%
1620
16th to endNight
5%326%7%45%6%7%12%37%
1703
August1st to 15thNight
5%425%5%35%5%8%12%39%
1692
16th to endNight
13%426%5%35%5%7%10%36%
1910
September1st to 15thNight
9%425%7%3446%8%42%
1944
16th to endNight
13%425%433446%47%
1818
October1st to 15thNight
10%5%13312346%55%
1815
16th to endNight
9%42432323359%
2109
November1st to 15thNight
11%413313336%56%
2276
16th to endNight
11%5%24424445%50%
2340
December1st to 15thNight
14%7%35%42335%6%43%
2340
16th to endNight
20%8%35%433347%35%
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
43%29%15%23%4
1612
16th to endDay
42%36%19%21%7%
1803
February1st to 15thDay
43%27%21%22%3
1752
16th to endDay
43%36%19%20%6%
1580
March1st to 15thDay
44%39%17%19%5%
1874
16th to endDay
43%410%22%15%3
2112
April1st to 15thDay
39%49%20%19%6%
2100
16th to endDay
35%49%22%23%4
2232
May1st to 15thDay
39%5%11%20%19%3
2331
16th to endDay
38%5%13%25%14%2
2435
June1st to 15thDay
43%7%16%22%9%1
2340
16th to endDay
32%7%16%25%15%2
2340
July1st to 15thDay
45%7%18%19%7%1
2201
16th to endDay
42%10%18%19%8%1
2310
August1st to 15thDay
40%9%18%20%9%1
2252
16th to endDay
51%8%13%14%10%1
2292
September1st to 15thDay
42%6%14%17%14%3
2004
16th to endDay
42%49%19%20%3
1815
October1st to 15thDay
35%37%19%25%8%
1815
16th to endDay
30%36%17%31%10%
1759
November1st to 15thDay
32%3417%32%9%
1582
16th to endDay
37%25%17%28%8%
1620
December1st to 15thDay
44%38%20%16%6%
1620
16th to endDay
53%28%16%14%5%
1728
January1st to 15thNight
42%36%18%23%4
2327
16th to endNight
43%25%18%22%6%
2418
February1st to 15thNight
40%27%20%19%9%
2112
16th to endNight
41%35%20%23%5%
1893
March1st to 15thNight
38%310%21%18%7%
2085
16th to endNight
37%39%25%19%4
2112
April1st to 15thNight
33%38%23%23%7%
1857
16th to endNight
31%49%25%21%7%
1728
May1st to 15thNight
33%6%13%21%22%2
1620
16th to endNight
32%5%13%29%15%3
1684
June1st to 15thNight
30%7%22%26%11%
1620
16th to endNight
27%7%22%21%17%2
1620
July1st to 15thNight
36%7%19%24%10%2
1530
16th to endNight
35%8%21%21%11%2
1595
August1st to 15thNight
34%7%19%24%12%2
1681
16th to endNight
40%7%18%17%13%1
1910
September1st to 15thNight
37%6%15%20%14%5%
1944
16th to endNight
37%410%22%19%5%
1818
October1st to 15thNight
30%39%21%26%8%
1815
16th to endNight
30%2416%32%13%
2109
November1st to 15thNight
30%25%17%31%12%
2276
16th to endNight
35%26%18%27%9%
2340
December1st to 15thNight
41%38%20%18%6%
2340
16th to endNight
48%37%17%18%4
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%22%40%12%5%2
90
16th to endDay
20%29%42%34
96
February1st to 15thDay
15%34%37%7%4
90
16th to endDay
22%20%45%11%
81
March1st to 15thDay
22%17%35%18%5%
164
16th to endDay
17%12%35%21%11%2
288
April1st to 15thDay
14%17%29%19%16%2
270
16th to endDay
12%6%29%24%21%5%
270
May1st to 15thDay
11%9%29%23%14%11%
288
16th to endDay
13%419%30%17%14%
331
June1st to 15thDay
10%211%21%29%24%
315
16th to endDay
6%15%27%24%25%
315
July1st to 15thDay
7%36%25%25%30%
305
16th to endDay
7%15%24%34%26%
326
August1st to 15thDay
12%26%27%31%20%
313
16th to endDay
17%7%29%27%18%
332
September1st to 15thDay
16%5%9%20%28%20%
315
16th to endDay
20%114%27%25%9%
254
October1st to 15thDay
17%322%25%21%8%
255
16th to endDay
16%8%19%21%26%6%
256
November1st to 15thDay
26%20%17%22%12%1
90
16th to endDay
10%11%45%18%13%1
90
December1st to 15thDay
23%25%28%16%5%
90
16th to endDay
29%14%35%14%5%1
96
January1st to 15thNight
23%18%29%21%6%
720
16th to endNight
19%20%32%24%4
768
February1st to 15thNight
18%17%35%25%3
704
16th to endNight
20%20%33%21%3
631
March1st to 15thNight
16%17%35%23%7%
720
16th to endNight
13%15%29%26%13%
768
April1st to 15thNight
13%13%32%25%14%1
599
16th to endNight
12%11%25%33%16%1
540
May1st to 15thNight
9%7%24%31%22%3
540
16th to endNight
10%217%31%32%6%
563
June1st to 15thNight
5%113%31%33%14%
540
16th to endNight
5%9%32%43%9%
540
July1st to 15thNight
6%18%26%43%13%
510
16th to endNight
6%6%26%45%13%
564
August1st to 15thNight
7%5%30%45%11%
539
16th to endNight
13%16%26%40%10%
573
September1st to 15thNight
12%19%25%39%12%
684
16th to endNight
17%114%34%28%3
658
October1st to 15thNight
13%424%26%25%5%
660
16th to endNight
11%11%23%27%22%4
704
November1st to 15thNight
13%9%25%25%23%2
700
16th to endNight
16%15%28%26%12%
720
December1st to 15thNight
18%15%30%25%9%
720
16th to endNight
25%15%28%23%7%
768
Page generated at 2017-09-16 17:07:01. Version ac04

Copyright 2017 A. Danko


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