Erwin W. Fick Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Erwin W. Fick Observatory clear sky chart from 2005-11-05 to 2017-12-02.

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%
16334
19%
47852
11%
16287
46%
16287
27%
30576

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
31%
900
15%
2437
6%
895
38%
895
24%
1653
January16th to endNight
27%
960
17%
2496
6%
960
35%
960
21%
1816
February1st to 15thNight
26%
880
11%
2288
4%
876
31%
876
19%
1704
February16th to endNight
29%
735
20%
1997
7%
735
39%
735
26%
1325
March1st to 15thNight
35%
540
21%
1980
15%
540
45%
540
24%
1178
March16th to endNight
25%
576
12%
2112
7%
576
34%
576
16%
1447
April1st to 15thNight
32%
539
18%
1812
13%
539
42%
539
22%
1165
April16th to endNight
31%
540
17%
1692
11%
540
43%
540
21%
1158
May1st to 15thNight
38%
540
16%
1596
10%
540
45%
540
26%
1026
May16th to endNight
43%
563
18%
1498
8%
561
49%
561
30%
986
June1st to 15thNight
52%
540
15%
1440
6%
540
56%
540
33%
925
June16th to endNight
53%
540
19%
1440
9%
540
56%
540
41%
846
July1st to 15thNight
69%
510
17%
1360
10%
510
70%
510
47%
766
July16th to endNight
73%
564
23%
1559
19%
531
75%
531
47%
808
August1st to 15thNight
69%
539
21%
1610
21%
536
71%
536
36%
930
August16th to endNight
62%
573
22%
1806
24%
573
67%
573
33%
1042
September1st to 15thNight
58%
540
26%
1800
26%
540
65%
540
36%
955
September16th to endNight
52%
561
26%
1998
20%
561
62%
561
34%
1069
October1st to 15thNight
38%
720
25%
2160
14%
720
46%
720
31%
1302
October16th to endNight
35%
768
24%
2304
12%
768
44%
768
29%
1386
November1st to 15thNight
35%
861
23%
2502
12%
861
44%
861
32%
1503
November16th to endNight
30%
975
20%
2730
9%
975
39%
975
28%
1734
December1st to 15thNight
24%
910
13%
2547
5%
910
32%
910
18%
1849
December16th to endNight
25%
960
15%
2688
6%
960
34%
960
17%
2003

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%7%35%5%3445%7%39%
48587
Night
12%6%25%424446%45%
48032
Cloud CoverDay
11%6%16%5%423346%34%
48598
Night
10%5%16%4423345%39%
48036
Cloud CoverDay
13%7%35%5%3445%7%39%
48596
Night
12%6%35%424446%44%
48036
TransparencyDay
43%6%13%22%12%1
48285
Night
39%5%13%24%14%2
47852
SeeingDay
15%7%27%30%15%3
6259
Night
15%8%31%32%11%
16334

By Month

Percentage Cloud Cover NE (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
8%9%6%6%7%445%6%7%34%
1498
16th to endDay
12%10%6%9%7%36%448%27%
1728
February1st to 15thDay
12%13%5%8%5%35%345%33%
1575
16th to endDay
14%8%38%5%35%345%37%
1485
March1st to 15thDay
13%9%5%7%5%34447%34%
1969
16th to endDay
19%10%46%6%24435%31%
2112
April1st to 15thDay
18%9%345%2435%6%36%
2135
16th to endDay
24%8%26%5%3335%5%31%
2265
May1st to 15thDay
18%7%35%5%35%5%5%7%33%
2352
16th to endDay
17%5%25%6%245%46%37%
2617
June1st to 15thDay
14%425%43445%8%41%
2520
16th to endDay
8%3245%35%5%6%9%45%
2520
July1st to 15thDay
7%4244345%6%9%47%
2520
16th to endDay
6%324435%5%6%10%47%
2500
August1st to 15thDay
8%5%25%5%3447%8%44%
2340
16th to endDay
12%42443445%7%45%
2396
September1st to 15thDay
10%414424347%51%
2160
16th to endDay
10%42343445%6%49%
1948
October1st to 15thDay
17%6%25%323335%47%
1800
16th to endDay
15%7%24423446%42%
1920
November1st to 15thDay
11%5%2442445%7%47%
1681
16th to endDay
15%8%25%424447%40%
1560
December1st to 15thDay
16%10%5%8%5%3435%6%29%
1450
16th to endDay
15%14%48%8%35%337%24%
1536
January1st to 15thNight
9%8%36%6%35%46%6%39%
2437
16th to endNight
11%11%47%5%34435%37%
2496
February1st to 15thNight
12%10%410%6%2445%6%32%
2285
16th to endNight
11%7%35%5%23446%44%
1997
March1st to 15thNight
13%7%25%423346%46%
1968
16th to endNight
17%9%36%5%24346%34%
2112
April1st to 15thNight
15%7%25%5%34346%41%
1812
16th to endNight
19%7%26%5%33445%38%
1692
May1st to 15thNight
15%42442346%7%42%
1596
16th to endNight
12%425%5%3445%8%43%
1496
June1st to 15thNight
9%325%5%345%5%7%47%
1440
16th to endNight
6%31342445%8%54%
1440
July1st to 15thNight
3234335%5%8%59%
1440
16th to endNight
411342447%9%57%
1666
August1st to 15thNight
6%41342345%8%54%
1620
16th to endNight
8%414423445%54%
1806
September1st to 15thNight
10%314422235%58%
1800
16th to endNight
9%5%13313447%54%
1998
October1st to 15thNight
15%423413345%51%
2160
16th to endNight
14%6%24323235%50%
2304
November1st to 15thNight
12%5%24313447%49%
2502
16th to endNight
13%6%34413346%46%
2730
December1st to 15thNight
15%11%46%435%45%5%32%
2547
16th to endNight
17%10%48%5%23446%31%
2688

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 15thDay
5%8%20%5%5%4445%6%28%
1498
16th to endDay
9%9%21%8%6%35%326%22%
1728
February1st to 15thDay
10%10%20%7%424235%28%
1575
16th to endDay
11%7%18%6%5%2433431%
1485
March1st to 15thDay
10%8%20%6%423335%30%
1980
16th to endDay
13%9%19%5%5%2333428%
2112
April1st to 15thDay
15%7%18%3422345%31%
2135
16th to endDay
20%7%19%5%423335%24%
2265
May1st to 15thDay
14%5%18%4424445%29%
2352
16th to endDay
15%5%19%45%23445%30%
2617
June1st to 15thDay
13%418%4323346%33%
2520
16th to endDay
6%317%34245%5%8%38%
2520
July1st to 15thDay
12%311%332445%8%38%
2520
16th to endDay
6%318%333445%7%39%
2500
August1st to 15thDay
7%311%442346%8%41%
2340
16th to endDay
10%410%443345%6%42%
2396
September1st to 15thDay
8%49%4323446%48%
2160
16th to endDay
9%410%342445%5%45%
1948
October1st to 15thDay
15%5%10%4422325%43%
1800
16th to endDay
13%6%10%4423446%39%
1920
November1st to 15thDay
8%416%4313346%43%
1681
16th to endDay
12%7%16%3323335%37%
1560
December1st to 15thDay
13%9%20%7%423345%24%
1450
16th to endDay
12%11%20%7%6%33325%22%
1536
January1st to 15thNight
6%7%19%5%5%3444434%
2437
16th to endNight
9%10%20%6%5%2333430%
2496
February1st to 15thNight
9%8%19%8%5%23345%28%
2278
16th to endNight
9%6%18%5%5%23335%36%
1997
March1st to 15thNight
11%6%18%4422245%38%
1980
16th to endNight
12%8%19%5%423336%30%
2112
April1st to 15thNight
12%6%18%342323436%
1812
16th to endNight
16%7%19%5%42243429%
1692
May1st to 15thNight
13%418%431235%6%36%
1595
16th to endNight
10%319%5%323346%35%
1496
June1st to 15thNight
8%318%4423446%38%
1440
16th to endNight
4217%332335%7%46%
1440
July1st to 15thNight
9%211%2323447%48%
1440
16th to endNight
3117%332335%7%48%
1666
August1st to 15thNight
5%310%342245%6%51%
1620
16th to endNight
6%39%4423335%51%
1806
September1st to 15thNight
8%39%4412235%54%
1800
16th to endNight
8%410%3213346%51%
1998
October1st to 15thNight
14%39%331234447%
2160
16th to endNight
11%6%10%4322235%47%
2304
November1st to 15thNight
10%415%4212336%44%
2502
16th to endNight
10%5%17%3312345%41%
2730
December1st to 15thNight
12%9%20%6%42334426%
2547
16th to endNight
14%8%20%8%41233427%
2688

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
8%10%5%6%6%5%45%6%7%33%
1498
16th to endDay
12%10%6%8%7%36%447%27%
1728
February1st to 15thDay
11%13%5%7%5%35%345%32%
1575
16th to endDay
14%8%38%6%25%345%36%
1485
March1st to 15thDay
13%9%5%7%5%35%5%47%33%
1980
16th to endDay
19%11%46%5%34436%30%
2110
April1st to 15thDay
18%9%35%43335%6%35%
2135
16th to endDay
24%8%26%423445%31%
2265
May1st to 15thDay
17%7%35%5%35%5%5%7%33%
2352
16th to endDay
17%6%25%6%35%446%37%
2617
June1st to 15thDay
14%5%25%5%3445%8%40%
2520
16th to endDay
8%3245%35%6%6%9%44%
2520
July1st to 15thDay
7%42442446%10%47%
2520
16th to endDay
6%3145%35%6%6%10%47%
2500
August1st to 15thDay
8%425%5%3447%8%44%
2340
16th to endDay
12%425%5%345%5%6%45%
2396
September1st to 15thDay
10%42342435%7%50%
2160
16th to endDay
10%42343445%6%49%
1948
October1st to 15thDay
17%6%34413235%47%
1800
16th to endDay
14%7%2442445%6%42%
1920
November1st to 15thDay
10%5%3442445%7%47%
1681
16th to endDay
15%8%24424447%40%
1560
December1st to 15thDay
16%10%5%8%5%3445%6%29%
1450
16th to endDay
15%14%49%7%35%437%24%
1536
January1st to 15thNight
9%8%46%6%35%45%6%38%
2437
16th to endNight
11%11%5%6%5%25%445%36%
2496
February1st to 15thNight
12%10%49%6%2445%6%32%
2278
16th to endNight
11%7%35%5%34446%44%
1997
March1st to 15thNight
13%7%2442335%6%45%
1980
16th to endNight
17%10%36%5%34346%33%
2112
April1st to 15thNight
15%7%25%5%34346%42%
1812
16th to endNight
18%7%25%5%23345%38%
1692
May1st to 15thNight
15%5%2442446%8%41%
1595
16th to endNight
12%425%5%35%448%43%
1496
June1st to 15thNight
8%425%5%245%5%7%47%
1440
16th to endNight
6%3133245%5%9%53%
1440
July1st to 15thNight
32123335%5%8%59%
1440
16th to endNight
411243447%10%56%
1666
August1st to 15thNight
5%42442445%7%54%
1620
16th to endNight
8%415%5%24445%54%
1806
September1st to 15thNight
10%314323335%58%
1800
16th to endNight
9%424213447%54%
1998
October1st to 15thNight
15%413413345%51%
2160
16th to endNight
13%6%24323335%50%
2304
November1st to 15thNight
11%5%24323447%49%
2502
16th to endNight
13%6%35%313346%46%
2730
December1st to 15thNight
15%11%46%5%25%45%6%32%
2547
16th to endNight
17%9%5%8%5%23446%31%
2688

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
47%6%14%19%11%
1499
16th to endDay
55%6%14%17%5%
1728
February1st to 15thDay
53%413%21%6%
1576
16th to endDay
48%6%15%16%10%2
1485
March1st to 15thDay
50%5%15%19%8%
1980
16th to endDay
55%5%14%18%5%1
2112
April1st to 15thDay
48%5%11%25%8%
2135
16th to endDay
54%5%11%19%8%
2265
May1st to 15thDay
48%7%13%21%9%
2352
16th to endDay
46%7%13%19%11%1
2621
June1st to 15thDay
40%7%15%20%14%
2520
16th to endDay
32%8%14%27%15%1
2520
July1st to 15thDay
32%7%15%27%12%3
2371
16th to endDay
29%8%16%27%15%1
2344
August1st to 15thDay
34%9%15%25%14%1
2326
16th to endDay
37%6%11%25%15%3
2396
September1st to 15thDay
32%5%14%26%19%2
2160
16th to endDay
34%5%13%29%16%
1948
October1st to 15thDay
40%49%24%19%1
1800
16th to endDay
41%6%11%24%15%1
1920
November1st to 15thDay
34%414%24%19%1
1681
16th to endDay
43%5%14%24%10%
1560
December1st to 15thDay
54%6%15%16%6%1
1450
16th to endDay
61%412%13%6%1
1536
January1st to 15thNight
44%5%17%19%13%
2437
16th to endNight
49%6%14%20%8%
2496
February1st to 15thNight
51%6%13%19%7%1
2288
16th to endNight
41%5%13%23%14%1
1997
March1st to 15thNight
39%413%27%13%1
1980
16th to endNight
51%5%14%19%7%1
2112
April1st to 15thNight
43%49%26%13%1
1812
16th to endNight
47%5%12%20%11%2
1692
May1st to 15thNight
39%6%16%23%12%1
1596
16th to endNight
38%7%14%23%14%2
1498
June1st to 15thNight
34%7%15%25%14%2
1440
16th to endNight
26%7%14%26%21%4
1440
July1st to 15thNight
21%8%18%32%15%4
1360
16th to endNight
20%6%18%31%20%1
1559
August1st to 15thNight
28%7%13%30%17%2
1610
16th to endNight
31%6%11%25%18%6%
1806
September1st to 15thNight
29%311%28%22%4
1800
16th to endNight
29%411%31%20%2
1998
October1st to 15thNight
35%49%25%21%3
2160
16th to endNight
36%412%25%18%2
2304
November1st to 15thNight
34%314%25%18%2
2502
16th to endNight
39%414%28%12%1
2730
December1st to 15thNight
51%5%13%20%8%
2547
16th to endNight
53%6%13%16%9%
2688

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%13%41%24%12
90
16th to endDay
18%6%41%29%31
96
February1st to 15thDay
11%25%31%27%4
90
16th to endDay
25%7%38%18%8%1
81
March1st to 15thDay
17%14%41%22%4
90
16th to endDay
34%10%34%15%5%
96
April1st to 15thDay
22%11%32%22%10%
254
16th to endDay
30%10%25%21%9%2
375
May1st to 15thDay
21%10%33%23%9%1
468
16th to endDay
17%9%29%27%13%2
517
June1st to 15thDay
11%5%29%31%19%3
495
16th to endDay
6%6%32%36%14%3
495
July1st to 15thDay
7%324%34%20%10%
475
16th to endDay
7%18%40%27%5%
515
August1st to 15thDay
9%19%35%28%5%
493
16th to endDay
15%216%33%24%7%
436
September1st to 15thDay
8%223%34%22%7%
315
16th to endDay
5%8%23%46%12%2
139
October1st to 15thDay
22%5%35%24%9%2
135
16th to endDay
18%10%37%24%9%
144
November1st to 15thDay
8%10%38%28%8%4
135
16th to endDay
28%15%34%19%2
135
December1st to 15thDay
17%21%32%19%8%1
94
16th to endDay
29%16%35%14%4
96
January1st to 15thNight
13%12%37%27%9%1
900
16th to endNight
17%10%36%29%5%
960
February1st to 15thNight
16%9%37%29%6%
880
16th to endNight
15%10%39%26%5%1
735
March1st to 15thNight
17%8%33%27%12%
540
16th to endNight
21%11%36%23%6%1
576
April1st to 15thNight
17%11%34%31%4
539
16th to endNight
21%9%33%25%8%1
540
May1st to 15thNight
17%9%31%32%9%
540
16th to endNight
14%5%31%34%14%
563
June1st to 15thNight
12%426%40%15%
540
16th to endNight
6%331%48%10%
540
July1st to 15thNight
5%20%45%27%1
510
16th to endNight
4115%48%28%1
564
August1st to 15thNight
6%112%50%25%2
539
16th to endNight
9%317%41%25%3
573
September1st to 15thNight
11%418%36%24%3
540
16th to endNight
11%428%33%19%2
561
October1st to 15thNight
18%7%32%28%12%1
720
16th to endNight
18%7%34%28%10%
768
November1st to 15thNight
15%9%36%28%9%
861
16th to endNight
15%13%37%24%8%
975
December1st to 15thNight
20%10%37%26%4
910
16th to endNight
21%10%33%28%6%
960
Page generated at 2017-12-03 10:16:37. Version ac04

Copyright 2017 A. Danko


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