Epiphany
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Epiphany clear sky chart from 2005-11-06 to 2024-02-20.

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
39%
24962
18%
80451
11%
24867
46%
24867
26%
50620

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
33%
940
11%
4418
7%
926
41%
926
12%
3367
January11th to 20thNight
31%
947
17%
4335
7%
930
37%
930
13%
2833
January21st to endNight
27%
1036
10%
4527
5%
1023
33%
1023
12%
3130
February1st to 10thNight
31%
950
14%
2470
5%
950
37%
950
24%
1733
February11th to 20thNight
33%
882
17%
2353
7%
878
39%
878
26%
1579
February21st to endNight
32%
592
19%
1776
7%
592
42%
592
26%
1169
March1st to 10thNight
30%
658
16%
2098
8%
658
38%
658
25%
1319
March11th to 20thNight
32%
540
20%
1980
13%
540
42%
540
22%
1252
March21st to endNight
30%
594
14%
2178
10%
594
39%
594
19%
1411
April1st to 10thNight
27%
540
14%
1891
9%
540
38%
540
22%
1184
April11th to 20thNight
31%
533
21%
1599
15%
533
41%
533
23%
1055
April21st to endNight
34%
540
18%
1620
13%
540
43%
540
25%
1054
May1st to 10thNight
36%
540
16%
1620
10%
540
43%
540
28%
1010
May11th to 20thNight
38%
531
18%
1593
9%
531
44%
531
31%
974
May21st to endNight
42%
583
13%
1593
4%
582
45%
582
27%
1074
June1st to 10thNight
53%
540
20%
1260
7%
540
56%
540
44%
792
June11th to 20thNight
47%
540
18%
1260
6%
540
50%
540
43%
790
June21st to endNight
56%
540
21%
1260
7%
540
59%
540
51%
738
July1st to 10thNight
65%
525
19%
1277
8%
525
67%
525
51%
737
July11th to 20thNight
61%
522
24%
1392
10%
522
65%
522
52%
739
July21st to endNight
64%
591
24%
1615
15%
558
67%
558
48%
839
August1st to 10thNight
63%
537
18%
1601
16%
534
65%
534
38%
911
August11th to 20thNight
60%
534
26%
1600
24%
534
68%
534
45%
850
August21st to endNight
58%
594
30%
1782
27%
594
68%
594
51%
878
September1st to 10thNight
52%
540
22%
1872
20%
540
61%
540
37%
972
September11th to 20thNight
51%
540
27%
1980
24%
540
62%
540
37%
992
September21st to endNight
45%
540
29%
1980
20%
540
60%
540
35%
999
October1st to 10thNight
36%
612
26%
2052
17%
612
45%
612
28%
1191
October11th to 20thNight
34%
720
25%
2160
13%
720
44%
720
32%
1266
October21st to endNight
36%
922
25%
2506
11%
922
45%
922
31%
1572
November1st to 10thNight
39%
925
26%
2405
11%
925
48%
925
37%
1444
November11th to 20thNight
33%
950
24%
2551
10%
950
43%
950
31%
1637
November21st to endNight
36%
950
22%
2660
13%
950
43%
950
33%
1636
December1st to 10thNight
30%
950
14%
2660
6%
950
38%
950
26%
1778
December11th to 20thNight
33%
948
15%
3363
9%
948
39%
948
21%
2042
December21st to endNight
27%
1036
10%
5164
7%
1026
36%
1026
11%
3673

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
11%7%36%5%35%5%5%7%42%
78214
Night
9%7%37%5%35%5%5%7%44%
81012
TransparencyDay
40%6%15%25%12%1
77923
Night
39%6%15%25%14%2
80826
SeeingDay
14%9%31%31%14%2
14882
Night
12%8%35%35%9%1
24996

By Month

Percentage Cloud Cover SW (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
8%12%5%13%10%5%7%8%5%6%22%
2510
11th to 20thDay
411%7%11%8%5%8%6%8%7%25%
2540
21st to endDay
6%12%8%12%9%5%8%6%5%6%25%
3051
February1st to 10thDay
9%11%410%8%46%5%6%6%30%
1710
11th to 20thDay
8%9%5%9%7%5%5%6%5%7%35%
1715
21st to endDay
9%10%49%8%46%5%5%6%34%
1480
March1st to 10thDay
12%10%49%6%3345%6%39%
1862
11th to 20thDay
13%8%47%6%3445%8%37%
1980
21st to endDay
17%10%5%7%7%4446%7%30%
2178
April1st to 10thDay
15%7%26%5%25%5%6%8%38%
2064
11th to 20thDay
19%10%36%5%35%45%6%35%
2309
21st to endDay
17%9%35%5%24448%39%
2340
May1st to 10thDay
16%7%25%6%45%5%5%6%39%
2340
11th to 20thDay
15%6%35%5%35%5%5%6%41%
2302
21st to endDay
18%5%35%435%5%5%8%40%
2680
June1st to 10thDay
12%4245%3445%9%47%
2700
11th to 20thDay
13%5%245%3446%8%47%
2700
21st to endDay
8%424435%6%6%8%50%
2700
July1st to 10thDay
7%3134245%7%10%55%
2641
11th to 20thDay
6%22333346%8%61%
2520
21st to endDay
6%213325%5%6%10%56%
2608
August1st to 10thDay
9%5%25%6%35%5%7%9%45%
2328
11th to 20thDay
8%4245%345%6%9%50%
2301
21st to endDay
7%32432445%7%59%
2574
September1st to 10thDay
12%5%24423447%52%
2084
11th to 20thDay
10%42443445%7%55%
1980
21st to endDay
12%5%24423445%54%
1980
October1st to 10thDay
15%6%24424436%51%
1890
11th to 20thDay
15%7%14323446%51%
1800
21st to endDay
16%7%25%42335%6%46%
1846
November1st to 10thDay
10%7%25%5%2446%7%47%
1673
11th to 20thDay
7%8%39%7%35%45%7%44%
1625
21st to endDay
10%8%36%4345%6%8%44%
1520
December1st to 10thDay
8%8%38%8%45%5%6%8%36%
1520
11th to 20thDay
8%10%5%9%7%46%5%5%7%35%
1721
21st to endDay
18%9%412%9%35%446%27%
2442
January1st to 10thNight
8%11%5%11%13%5%7%6%5%6%23%
4440
11th to 20thNight
48%5%9%9%48%6%10%8%29%
4430
21st to endNight
6%8%7%12%7%46%6%6%7%31%
4613
February1st to 10thNight
8%9%5%8%7%35%5%5%7%38%
2470
11th to 20thNight
8%9%38%6%445%6%6%42%
2352
21st to endNight
9%10%47%5%35%5%6%7%39%
1776
March1st to 10thNight
10%9%36%5%345%5%7%42%
2098
11th to 20thNight
12%9%47%6%35%446%41%
1980
21st to endNight
14%8%47%6%35%447%39%
2178
April1st to 10thNight
15%7%26%5%3445%7%41%
1891
11th to 20thNight
17%8%36%5%23346%42%
1599
21st to endNight
15%7%35%4345%5%8%41%
1620
May1st to 10thNight
14%5%245%35%45%8%45%
1620
11th to 20thNight
14%6%245%2435%8%48%
1593
21st to endNight
13%6%35%445%5%6%9%39%
1592
June1st to 10thNight
7%5%25%4345%5%7%55%
1260
11th to 20thNight
8%4345%2446%9%51%
1260
21st to endNight
6%31342446%9%59%
1260
July1st to 10thNight
5%31332347%9%59%
1315
11th to 20thNight
421332446%7%64%
1440
21st to endNight
3213425%5%6%8%60%
1710
August1st to 10thNight
6%414435%6%7%11%49%
1611
11th to 20thNight
7%3242235%5%8%59%
1600
21st to endNight
6%21332345%7%64%
1782
September1st to 10thNight
10%31332445%6%60%
1872
11th to 20thNight
7%42332345%6%59%
1980
21st to endNight
10%5%2432335%6%57%
1980
October1st to 10thNight
16%6%24424346%50%
2052
11th to 20thNight
13%6%24333446%52%
2160
21st to endNight
13%6%25%423346%50%
2506
November1st to 10thNight
8%5%25%434447%52%
2405
11th to 20thNight
7%7%37%6%345%5%7%45%
2551
21st to endNight
8%7%35%435%5%5%7%49%
2660
December1st to 10thNight
7%9%48%7%35%5%5%7%40%
2660
11th to 20thNight
8%8%47%6%345%5%7%43%
3471
21st to endNight
17%10%5%11%6%3445%6%28%
5225

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
59%7%14%14%5%
2511
11th to 20thDay
55%412%22%6%
2540
21st to endDay
57%8%15%13%6%
3051
February1st to 10thDay
52%8%15%16%9%
1710
11th to 20thDay
48%7%15%19%10%2
1724
21st to endDay
49%7%16%16%10%1
1480
March1st to 10thDay
47%5%16%23%8%1
1862
11th to 20thDay
47%6%12%25%10%
1980
21st to endDay
54%7%17%17%41
2178
April1st to 10thDay
42%7%14%25%10%1
2064
11th to 20thDay
49%6%10%22%11%2
2312
21st to endDay
45%6%14%24%11%
2340
May1st to 10thDay
45%6%13%22%13%
2340
11th to 20thDay
43%6%15%23%13%
2306
21st to endDay
43%7%14%24%11%
2680
June1st to 10thDay
34%7%17%29%13%1
2700
11th to 20thDay
34%7%16%26%14%3
2700
21st to endDay
30%8%16%30%14%2
2700
July1st to 10thDay
25%7%19%34%14%1
2570
11th to 20thDay
22%6%14%30%22%6%
2445
21st to endDay
23%8%16%30%20%3
2463
August1st to 10thDay
34%8%17%25%12%2
2314
11th to 20thDay
29%9%17%32%13%1
2301
21st to endDay
25%6%14%33%18%4
2574
September1st to 10thDay
32%5%13%29%19%2
2084
11th to 20thDay
29%6%16%31%16%1
1980
21st to endDay
32%5%11%32%19%1
1980
October1st to 10thDay
37%413%28%17%1
1890
11th to 20thDay
35%313%29%17%3
1800
21st to endDay
40%414%26%15%1
1846
November1st to 10thDay
35%6%17%25%13%3
1673
11th to 20thDay
41%6%15%25%13%1
1625
21st to endDay
39%5%18%24%13%1
1520
December1st to 10thDay
46%6%18%20%8%2
1520
11th to 20thDay
49%5%19%22%5%
1718
21st to endDay
59%412%19%6%
2442
January1st to 10thNight
59%6%11%16%7%
4440
11th to 20thNight
49%5%15%21%9%1
4430
21st to endNight
51%7%18%16%7%
4613
February1st to 10thNight
46%6%14%23%10%1
2470
11th to 20thNight
42%6%13%23%13%3
2353
21st to endNight
42%5%15%22%12%3
1776
March1st to 10thNight
41%5%19%24%9%2
2098
11th to 20thNight
44%5%11%26%13%1
1980
21st to endNight
46%6%16%23%8%1
2178
April1st to 10thNight
41%6%14%25%12%1
1891
11th to 20thNight
45%410%22%17%2
1599
21st to endNight
41%6%13%27%11%2
1620
May1st to 10thNight
37%7%15%26%14%1
1620
11th to 20thNight
35%6%14%26%17%2
1594
21st to endNight
41%7%15%22%14%1
1593
June1st to 10thNight
29%5%17%28%18%3
1260
11th to 20thNight
29%6%18%24%19%5%
1260
21st to endNight
22%6%17%31%20%3
1260
July1st to 10thNight
20%7%16%35%19%3
1277
11th to 20thNight
19%6%13%30%24%8%
1392
21st to endNight
20%7%15%31%23%4
1615
August1st to 10thNight
28%7%20%26%16%3
1601
11th to 20thNight
23%6%16%34%18%3
1600
21st to endNight
19%5%15%32%24%6%
1782
September1st to 10thNight
26%6%14%27%23%4
1872
11th to 20thNight
25%6%15%32%19%2
1980
21st to endNight
28%410%31%24%2
1980
October1st to 10thNight
36%413%26%20%1
2052
11th to 20thNight
33%5%10%29%19%4
2160
21st to endNight
36%5%13%24%20%2
2506
November1st to 10thNight
32%415%25%20%4
2405
11th to 20thNight
37%5%15%24%16%2
2551
21st to endNight
35%5%16%27%16%1
2660
December1st to 10thNight
42%6%18%24%9%1
2660
11th to 20thNight
40%5%21%26%7%
3473
21st to endNight
56%5%12%20%6%1
5225

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
15%11%28%36%10%
270
11th to 20thDay
14%13%32%34%7%1
270
21st to endDay
14%10%37%27%11%1
297
February1st to 10thDay
11%15%41%29%4
270
11th to 20thDay
15%15%36%25%8%1
267
21st to endDay
14%16%38%27%5%1
198
March1st to 10thDay
15%14%38%28%4
240
11th to 20thDay
18%8%36%27%10%2
240
21st to endDay
24%12%28%27%8%1
264
April1st to 10thDay
24%17%35%19%4
324
11th to 20thDay
24%15%32%22%7%1
590
21st to endDay
23%13%28%25%10%2
600
May1st to 10thDay
20%10%33%26%10%1
603
11th to 20thDay
19%11%28%25%15%2
625
21st to endDay
18%6%30%31%13%2
679
June1st to 10thDay
9%7%25%34%21%5%
630
11th to 20thDay
13%6%34%30%15%3
630
21st to endDay
10%6%27%39%16%2
630
July1st to 10thDay
6%323%39%25%4
621
11th to 20thDay
6%333%39%17%2
618
21st to endDay
6%326%43%20%2
684
August1st to 10thDay
9%421%41%23%2
626
11th to 20thDay
9%425%37%22%4
615
21st to endDay
7%5%28%36%21%3
693
September1st to 10thDay
13%8%30%30%17%2
374
11th to 20thDay
9%6%34%32%16%3
270
21st to endDay
14%15%33%24%12%1
270
October1st to 10thDay
20%8%31%26%13%3
270
11th to 20thDay
17%13%33%24%11%1
270
21st to endDay
19%15%34%23%8%1
297
November1st to 10thDay
19%13%31%27%10%1
270
11th to 20thDay
12%17%39%25%7%
270
21st to endDay
17%17%30%28%8%
270
December1st to 10thDay
10%9%41%28%10%1
270
11th to 20thDay
16%10%42%26%6%
270
21st to endDay
21%12%37%24%5%1
297
January1st to 10thNight
10%10%36%34%7%1
950
11th to 20thNight
11%11%36%34%7%1
950
21st to endNight
13%9%38%31%9%
1045
February1st to 10thNight
13%11%38%32%5%
950
11th to 20thNight
11%13%36%32%7%1
882
21st to endNight
14%8%38%31%8%1
592
March1st to 10thNight
14%10%41%32%41
658
11th to 20thNight
16%8%39%32%5%
540
21st to endNight
18%10%36%28%7%1
594
April1st to 10thNight
17%12%40%28%3
540
11th to 20thNight
20%13%32%27%8%
533
21st to endNight
17%11%37%28%7%1
540
May1st to 10thNight
16%8%37%29%10%
540
11th to 20thNight
15%6%39%28%12%1
531
21st to endNight
15%7%33%36%9%
584
June1st to 10thNight
7%7%30%39%16%1
540
11th to 20thNight
10%5%34%41%10%1
540
21st to endNight
6%430%45%14%
540
July1st to 10thNight
5%323%48%21%
525
11th to 20thNight
4229%51%13%
522
21st to endNight
3227%53%14%1
591
August1st to 10thNight
6%323%52%16%
537
11th to 20thNight
8%128%41%21%1
534
21st to endNight
6%230%44%17%1
594
September1st to 10thNight
10%431%39%14%1
540
11th to 20thNight
7%5%34%39%13%2
540
21st to endNight
10%6%36%35%12%1
540
October1st to 10thNight
18%10%33%30%9%
612
11th to 20thNight
17%9%36%29%9%
720
21st to endNight
17%11%34%31%8%
922
November1st to 10thNight
10%9%37%34%9%1
925
11th to 20thNight
11%11%39%30%8%1
950
21st to endNight
11%9%37%35%7%
950
December1st to 10thNight
12%12%39%29%7%
950
11th to 20thNight
14%9%34%34%8%
950
21st to endNight
19%11%33%30%7%
1045
Page generated at 2024-02-17 05:28:40. Version ac07

Copyright 2024 Attilla Danko


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