Broad Creek
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Broad Creek clear sky chart from 2005-11-06 to 2024-01-13.

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
33%
23312
21%
74615
10%
23262
45%
23262
23%
46382

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
15%
760
24%
2649
7%
757
37%
757
19%
1577
January11th to 20thNight
21%
729
22%
2423
8%
729
39%
729
18%
1550
January21st to endNight
17%
792
25%
2574
6%
792
39%
792
20%
1556
February1st to 10thNight
17%
720
18%
2340
5%
720
32%
720
16%
1513
February11th to 20thNight
11%
703
20%
2186
2%
700
33%
700
15%
1414
February21st to endNight
15%
592
24%
1776
7%
592
35%
592
16%
1179
March1st to 10thNight
18%
720
24%
2086
7%
720
38%
720
23%
1264
March11th to 20thNight
20%
720
21%
1980
7%
720
33%
720
20%
1299
March21st to endNight
19%
792
22%
2098
6%
792
33%
792
23%
1399
April1st to 10thNight
17%
720
20%
1800
3%
720
28%
720
21%
1225
April11th to 20thNight
28%
711
21%
1775
6%
711
35%
711
30%
1148
April21st to endNight
27%
720
20%
1800
5%
720
35%
720
26%
1224
May1st to 10thNight
33%
606
17%
1686
8%
606
39%
606
24%
1136
May11th to 20thNight
30%
354
18%
1416
12%
354
41%
354
17%
890
May21st to endNight
49%
389
15%
1551
14%
388
55%
388
20%
918
June1st to 10thNight
48%
360
20%
1440
19%
360
58%
360
24%
829
June11th to 20thNight
48%
360
16%
1440
17%
360
55%
360
22%
868
June21st to endNight
55%
360
18%
1440
19%
360
62%
360
26%
801
July1st to 10thNight
54%
350
14%
1400
15%
350
58%
350
20%
854
July11th to 20thNight
64%
348
18%
1392
21%
348
67%
348
27%
756
July21st to endNight
60%
535
18%
1620
14%
506
65%
506
31%
956
August1st to 10thNight
59%
537
18%
1600
12%
534
62%
534
30%
986
August11th to 20thNight
55%
643
17%
1707
11%
643
57%
643
28%
1148
August21st to endNight
58%
792
19%
1980
10%
792
60%
792
33%
1309
September1st to 10thNight
48%
720
22%
1800
10%
720
54%
720
32%
1194
September11th to 20thNight
57%
720
32%
1800
20%
720
62%
720
40%
1108
September21st to endNight
44%
720
24%
2031
15%
720
52%
720
27%
1337
October1st to 10thNight
40%
720
18%
2160
14%
720
48%
720
25%
1391
October11th to 20thNight
39%
720
25%
2160
17%
720
51%
720
30%
1278
October21st to endNight
30%
792
27%
2376
14%
792
47%
792
27%
1443
November1st to 10thNight
34%
740
26%
2400
14%
740
53%
740
29%
1346
November11th to 20thNight
28%
760
26%
2470
14%
760
45%
760
23%
1480
November21st to endNight
29%
760
24%
2641
11%
760
47%
760
22%
1517
December1st to 10thNight
20%
760
19%
2660
6%
760
37%
760
17%
1689
December11th to 20thNight
19%
760
21%
3185
6%
759
38%
759
15%
1902
December21st to endNight
23%
827
14%
4773
8%
817
39%
817
11%
2898

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
14%6%25%5%35%5%6%8%41%
74711
Night
15%6%25%5%3445%7%43%
75016
TransparencyDay
41%411%24%16%3
74418
Night
41%411%24%17%3
74829
SeeingDay
20%15%28%22%11%4
13828
Night
19%14%29%26%11%1
23321

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
14%7%25%435%5%5%7%42%
1517
11th to 20thDay
16%7%36%5%35%45%7%41%
1578
21st to endDay
15%8%37%6%45%45%6%38%
1782
February1st to 10thDay
16%9%25%6%3446%7%38%
1620
11th to 20thDay
17%7%25%5%3445%7%41%
1661
21st to endDay
19%11%36%424335%39%
1480
March1st to 10thDay
13%6%35%5%34446%48%
1872
11th to 20thDay
16%7%35%5%3435%8%41%
1980
21st to endDay
19%7%36%6%3435%6%39%
2257
April1st to 10thDay
15%6%35%5%3446%8%41%
2160
11th to 20thDay
14%5%245%345%47%45%
2134
21st to endDay
18%5%25%4345%6%7%40%
2160
May1st to 10thDay
18%6%25%5%35%45%7%38%
2285
11th to 20thDay
20%6%345%35%5%6%7%36%
2478
21st to endDay
14%6%245%35%47%9%40%
2725
June1st to 10thDay
12%5%36%5%36%5%7%11%38%
2520
11th to 20thDay
13%5%35%7%45%6%6%9%38%
2520
21st to endDay
10%4245%35%5%7%10%43%
2520
July1st to 10thDay
10%5%25%6%35%6%7%10%41%
2520
11th to 20thDay
6%325%5%46%8%7%11%43%
2520
21st to endDay
9%5%37%6%46%6%8%10%37%
2600
August1st to 10thDay
10%5%25%6%46%7%7%9%38%
2327
11th to 20thDay
10%5%26%6%46%7%6%10%39%
2174
21st to endDay
12%5%245%45%6%8%8%42%
2376
September1st to 10thDay
16%5%25%5%3445%7%43%
2160
11th to 20thDay
13%5%24433347%51%
2160
21st to endDay
18%6%26%435%46%7%39%
1922
October1st to 10thDay
17%7%25%4245%47%44%
1800
11th to 20thDay
18%4334345%5%6%46%
1800
21st to endDay
17%6%25%43445%5%46%
1980
November1st to 10thDay
13%5%243335%46%51%
1676
11th to 20thDay
16%5%2442445%6%48%
1710
21st to endDay
16%435%434446%45%
1535
December1st to 10thDay
17%7%35%435%45%7%39%
1520
11th to 20thDay
19%7%3442445%7%41%
1910
21st to endDay
17%6%37%6%45%6%5%6%36%
2772
January1st to 10thNight
16%6%25%424447%46%
2649
11th to 20thNight
19%7%344245%5%6%40%
2423
21st to endNight
14%7%25%5%3345%6%46%
2574
February1st to 10thNight
16%8%35%6%3445%6%39%
2340
11th to 20thNight
17%8%35%4345%45%42%
2184
21st to endNight
17%7%36%5%35%445%41%
1776
March1st to 10thNight
14%4235%245%5%6%49%
2086
11th to 20thNight
17%7%25%424446%43%
1980
21st to endNight
17%7%35%434347%43%
2098
April1st to 10thNight
16%7%346%245%6%6%41%
1800
11th to 20thNight
16%5%35%43446%8%44%
1775
21st to endNight
19%6%2442435%6%43%
1800
May1st to 10thNight
17%6%36%6%235%5%7%39%
1686
11th to 20thNight
20%6%36%5%2445%7%37%
1415
21st to endNight
16%5%245%346%5%9%41%
1550
June1st to 10thNight
13%435%5%3445%9%45%
1440
11th to 20thNight
12%6%26%6%35%5%6%9%40%
1440
21st to endNight
10%4246%446%7%10%43%
1440
July1st to 10thNight
10%5%36%6%45%6%8%9%38%
1440
11th to 20thNight
6%425%5%46%6%7%11%45%
1440
21st to endNight
8%5%26%5%46%5%7%9%44%
1715
August1st to 10thNight
10%4246%35%7%7%9%42%
1611
11th to 20thNight
11%7%26%6%45%5%5%9%40%
1707
21st to endNight
13%4245%35%5%6%8%44%
1980
September1st to 10thNight
15%6%25%5%24446%46%
1800
11th to 20thNight
12%6%24323347%54%
1800
21st to endNight
18%6%25%434447%42%
2031
October1st to 10thNight
19%7%26%43335%5%44%
2160
11th to 20thNight
17%5%24323447%49%
2160
21st to endNight
18%5%24323346%48%
2376
November1st to 10thNight
12%42443445%6%53%
2400
11th to 20thNight
17%5%25%423346%48%
2470
21st to endNight
13%4245%25%45%7%47%
2641
December1st to 10thNight
18%7%35%6%34446%40%
2660
11th to 20thNight
18%5%245%4445%6%43%
3285
21st to endNight
17%8%35%5%45%5%6%8%35%
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
41%412%24%15%4
1518
11th to 20thDay
45%313%22%13%3
1578
21st to endDay
48%39%24%14%3
1782
February1st to 10thDay
45%413%25%11%2
1620
11th to 20thDay
45%39%27%14%3
1670
21st to endDay
49%38%22%13%5%
1480
March1st to 10thDay
39%211%28%17%2
1872
11th to 20thDay
43%311%20%18%5%
1980
21st to endDay
48%37%20%18%3
2257
April1st to 10thDay
42%411%20%18%5%
2160
11th to 20thDay
40%5%10%22%17%6%
2134
21st to endDay
43%310%20%19%4
2160
May1st to 10thDay
46%49%21%16%3
2285
11th to 20thDay
48%5%12%20%13%3
2482
21st to endDay
40%5%16%24%13%2
2725
June1st to 10thDay
41%5%12%25%15%2
2520
11th to 20thDay
42%6%12%24%13%2
2520
21st to endDay
34%6%16%26%17%1
2520
July1st to 10thDay
38%6%14%23%15%3
2450
11th to 20thDay
32%7%15%28%15%3
2445
21st to endDay
40%7%12%24%15%2
2455
August1st to 10thDay
39%7%12%26%14%1
2314
11th to 20thDay
39%7%14%22%16%2
2174
21st to endDay
38%6%14%24%15%4
2376
September1st to 10thDay
41%5%11%21%18%4
2160
11th to 20thDay
35%48%28%22%4
2160
21st to endDay
45%46%21%21%3
1922
October1st to 10thDay
41%410%25%18%2
1800
11th to 20thDay
39%311%23%22%2
1800
21st to endDay
41%38%27%18%2
1980
November1st to 10thDay
34%313%26%20%4
1676
11th to 20thDay
38%39%25%22%3
1710
21st to endDay
40%310%31%13%3
1535
December1st to 10thDay
45%415%23%12%1
1520
11th to 20thDay
44%310%31%11%2
1906
21st to endDay
49%313%22%13%1
2772
January1st to 10thNight
40%310%26%17%4
2649
11th to 20thNight
45%313%25%13%1
2423
21st to endNight
40%29%28%18%3
2574
February1st to 10thNight
46%312%24%12%2
2340
11th to 20thNight
44%39%22%18%4
2186
21st to endNight
47%38%21%16%5%
1776
March1st to 10thNight
36%311%27%20%3
2086
11th to 20thNight
43%310%21%18%4
1980
21st to endNight
44%39%21%18%5%
2098
April1st to 10thNight
44%39%20%19%5%
1800
11th to 20thNight
38%311%22%20%5%
1775
21st to endNight
42%49%22%18%6%
1800
May1st to 10thNight
45%410%20%17%4
1686
11th to 20thNight
47%413%15%19%2
1416
21st to endNight
40%6%18%21%12%3
1551
June1st to 10thNight
38%5%11%26%18%2
1440
11th to 20thNight
42%414%22%16%1
1440
21st to endNight
35%6%13%28%16%2
1440
July1st to 10thNight
42%6%17%19%13%3
1400
11th to 20thNight
32%7%16%25%17%2
1392
21st to endNight
35%5%16%23%18%2
1620
August1st to 10thNight
36%7%16%24%16%1
1600
11th to 20thNight
42%6%13%22%16%2
1707
21st to endNight
38%5%14%24%16%4
1980
September1st to 10thNight
41%311%21%19%5%
1800
11th to 20thNight
33%39%26%25%4
1800
21st to endNight
43%48%22%21%3
2031
October1st to 10thNight
44%310%23%18%2
2160
11th to 20thNight
37%310%29%19%3
2160
21st to endNight
38%39%28%20%3
2376
November1st to 10thNight
34%310%28%20%5%
2400
11th to 20thNight
39%38%24%20%5%
2470
21st to endNight
38%311%29%18%2
2641
December1st to 10thNight
46%311%24%15%1
2660
11th to 20thNight
42%311%22%17%4
3288
21st to endNight
47%314%23%12%1
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
28%27%28%13%21
180
11th to 20thDay
28%31%26%15%1
218
21st to endDay
22%39%26%10%31
264
February1st to 10thDay
30%28%31%9%21
240
11th to 20thDay
31%27%37%41
328
21st to endDay
35%24%28%11%2
346
March1st to 10thDay
25%24%31%17%2
420
11th to 20thDay
27%24%33%10%41
420
21st to endDay
26%24%32%12%41
462
April1st to 10thDay
21%26%35%12%5%1
420
11th to 20thDay
22%18%30%19%8%3
412
21st to endDay
27%18%35%14%5%1
420
May1st to 10thDay
27%18%30%16%8%2
423
11th to 20thDay
23%17%28%23%8%2
447
21st to endDay
20%8%24%26%18%4
485
June1st to 10thDay
14%12%32%25%14%4
450
11th to 20thDay
17%11%28%28%14%4
450
21st to endDay
13%9%31%30%12%5%
450
July1st to 10thDay
12%321%31%26%7%
445
11th to 20thDay
4423%37%24%8%
444
21st to endDay
13%5%26%31%19%5%
488
August1st to 10thDay
12%424%32%22%7%
446
11th to 20thDay
11%6%18%35%21%9%
439
21st to endDay
12%426%30%18%10%
495
September1st to 10thDay
19%7%19%26%19%9%
450
11th to 20thDay
17%5%24%27%18%9%
450
21st to endDay
25%10%24%24%14%3
450
October1st to 10thDay
24%8%23%24%14%6%
450
11th to 20thDay
18%15%29%23%13%2
450
21st to endDay
20%17%36%17%8%2
495
November1st to 10thDay
17%16%31%23%11%3
368
11th to 20thDay
20%22%32%18%8%1
370
21st to endDay
23%20%30%21%6%1
195
December1st to 10thDay
24%26%33%12%31
180
11th to 20thDay
31%27%27%12%4
180
21st to endDay
24%20%33%16%7%
198
January1st to 10thNight
20%21%39%17%3
760
11th to 20thNight
24%17%33%23%3
729
21st to endNight
19%22%37%19%1
792
February1st to 10thNight
22%22%34%20%2
720
11th to 20thNight
23%26%36%14%1
703
21st to endNight
22%25%34%16%3
592
March1st to 10thNight
21%23%34%18%4
720
11th to 20thNight
23%22%32%17%5%
720
21st to endNight
20%17%39%18%5%1
792
April1st to 10thNight
22%23%33%18%4
720
11th to 20thNight
20%14%35%25%6%
711
21st to endNight
23%14%32%24%7%
720
May1st to 10thNight
21%12%30%30%7%
606
11th to 20thNight
22%10%31%29%8%
354
21st to endNight
17%6%19%39%17%2
389
June1st to 10thNight
14%428%38%15%1
360
11th to 20thNight
14%5%24%39%16%1
360
21st to endNight
10%323%45%19%
360
July1st to 10thNight
12%319%38%25%3
350
11th to 20thNight
7%218%39%30%3
348
21st to endNight
9%318%44%24%2
535
August1st to 10thNight
11%316%41%27%3
537
11th to 20thNight
15%414%35%30%2
643
21st to endNight
14%416%38%24%4
792
September1st to 10thNight
18%420%32%22%4
720
11th to 20thNight
13%6%17%34%25%5%
720
21st to endNight
20%5%23%31%19%2
720
October1st to 10thNight
21%8%23%24%19%4
720
11th to 20thNight
20%11%26%31%12%1
720
21st to endNight
21%13%32%23%12%
792
November1st to 10thNight
14%12%35%27%11%1
740
11th to 20thNight
20%18%30%25%7%1
760
21st to endNight
16%20%31%25%8%
760
December1st to 10thNight
24%18%33%17%7%1
760
11th to 20thNight
20%18%38%20%5%
760
21st to endNight
20%19%33%25%3
836
Page generated at 2024-01-10 01:25:05. Version ac07

Copyright 2024 Attilla Danko


Broad Creek Clear Sky Chart |Charts Home