WHOPPER Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the WHOPPER Observatory clear sky chart from 2005-11-06 to 2024-01-16.

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
28%
23151
19%
74676
9%
23109
41%
23109
20%
47824

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
14%
760
22%
2649
6%
757
33%
757
17%
1615
January11th to 20thNight
18%
744
18%
2602
5%
744
36%
744
14%
1706
January21st to endNight
14%
792
22%
2574
5%
792
34%
792
17%
1590
February1st to 10thNight
14%
720
17%
2340
4%
720
30%
720
15%
1540
February11th to 20thNight
11%
703
19%
2141
3%
700
30%
700
14%
1441
February21st to endNight
15%
592
25%
1776
8%
592
36%
592
16%
1160
March1st to 10thNight
19%
720
21%
2160
8%
720
35%
720
19%
1352
March11th to 20thNight
17%
720
22%
1998
6%
720
33%
720
19%
1335
March21st to endNight
17%
792
21%
2039
5%
792
29%
792
21%
1412
April1st to 10thNight
17%
720
18%
1800
3%
720
25%
720
19%
1259
April11th to 20thNight
22%
711
18%
1775
5%
711
28%
711
23%
1223
April21st to endNight
24%
720
19%
1800
4%
720
32%
720
25%
1215
May1st to 10thNight
25%
543
15%
1623
7%
543
32%
543
16%
1151
May11th to 20thNight
25%
354
18%
1416
10%
354
39%
354
16%
902
May21st to endNight
43%
388
15%
1551
14%
388
51%
388
18%
961
June1st to 10thNight
40%
360
18%
1440
15%
360
52%
360
20%
868
June11th to 20thNight
40%
360
14%
1440
11%
360
51%
360
20%
886
June21st to endNight
49%
360
16%
1440
16%
360
58%
360
25%
824
July1st to 10thNight
48%
350
13%
1400
15%
350
53%
350
19%
864
July11th to 20thNight
52%
348
17%
1392
18%
348
58%
348
23%
811
July21st to endNight
49%
394
17%
1486
15%
372
57%
372
24%
855
August1st to 10thNight
55%
524
16%
1588
11%
522
59%
522
27%
1043
August11th to 20thNight
51%
684
15%
1748
9%
684
53%
684
27%
1220
August21st to endNight
50%
792
18%
1980
8%
792
53%
792
30%
1335
September1st to 10thNight
41%
720
21%
1800
8%
720
47%
720
29%
1234
September11th to 20thNight
49%
720
28%
1837
17%
720
55%
720
35%
1149
September21st to endNight
42%
720
25%
1980
15%
720
51%
720
29%
1282
October1st to 10thNight
36%
720
17%
2142
11%
720
44%
720
23%
1420
October11th to 20thNight
35%
720
23%
2160
13%
720
48%
720
26%
1331
October21st to endNight
26%
792
22%
2466
11%
792
41%
792
22%
1579
November1st to 10thNight
32%
740
25%
2407
11%
740
50%
740
26%
1391
November11th to 20thNight
25%
760
25%
2470
11%
760
43%
760
20%
1523
November21st to endNight
23%
760
22%
2603
9%
760
40%
760
20%
1566
December1st to 10thNight
18%
760
18%
2660
7%
760
33%
760
14%
1734
December11th to 20thNight
19%
760
19%
3194
5%
759
37%
759
13%
1985
December21st to endNight
17%
828
12%
4799
5%
817
33%
817
8%
3062

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
16%7%35%5%35%5%5%7%38%
74765
Night
17%7%35%5%3445%7%41%
75026
TransparencyDay
44%6%11%22%15%2
74470
Night
42%5%11%23%16%2
74855
SeeingDay
21%18%30%19%9%2
13811
Night
20%16%30%24%8%1
23160

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 10thDay
14%8%36%6%35%5%5%6%40%
1517
11th to 20thDay
16%7%39%7%45%5%5%6%33%
1480
21st to endDay
14%8%36%5%45%45%7%38%
1778
February1st to 10thDay
18%8%36%5%345%6%6%35%
1620
11th to 20thDay
16%8%37%5%445%5%6%39%
1705
21st to endDay
20%9%36%6%25%44436%
1480
March1st to 10thDay
14%8%346%3445%7%42%
1797
11th to 20thDay
15%8%36%5%345%5%9%36%
1957
21st to endDay
21%7%35%4345%5%6%38%
2316
April1st to 10thDay
17%8%36%5%35%45%7%38%
2160
11th to 20thDay
17%7%35%6%3446%7%39%
2134
21st to endDay
18%6%36%5%45%5%5%6%39%
2160
May1st to 10thDay
20%8%35%5%35%46%7%33%
2349
11th to 20thDay
20%6%35%6%45%5%47%36%
2478
21st to endDay
15%7%25%5%35%5%6%8%39%
2725
June1st to 10thDay
15%6%35%5%36%6%6%9%36%
2520
11th to 20thDay
15%6%36%5%46%6%6%8%35%
2520
21st to endDay
14%6%25%445%5%6%8%41%
2520
July1st to 10thDay
11%6%37%6%46%6%6%8%37%
2520
11th to 20thDay
10%5%35%5%36%7%7%9%41%
2520
21st to endDay
12%6%36%6%46%6%7%8%36%
2744
August1st to 10thDay
11%7%36%6%36%7%7%8%37%
2337
11th to 20thDay
12%6%25%7%45%5%6%7%39%
2134
21st to endDay
14%6%25%5%45%5%6%7%41%
2376
September1st to 10thDay
16%4246%345%6%8%41%
2160
11th to 20thDay
13%424424448%49%
2122
21st to endDay
18%6%25%5%346%46%41%
1980
October1st to 10thDay
20%5%25%5%345%5%7%40%
1816
11th to 20thDay
17%6%245%3445%7%44%
1800
21st to endDay
22%5%35%4345%5%7%38%
1888
November1st to 10thDay
15%7%34423345%52%
1671
11th to 20thDay
18%4245%245%5%5%45%
1710
21st to endDay
16%5%35%5%345%47%43%
1573
December1st to 10thDay
21%7%36%6%345%47%34%
1520
11th to 20thDay
21%7%25%435%45%7%38%
1906
21st to endDay
18%9%48%7%46%5%5%7%27%
2772
January1st to 10thNight
16%6%35%5%3445%7%42%
2649
11th to 20thNight
20%7%35%5%35%45%8%36%
2602
21st to endNight
13%8%35%435%45%6%43%
2574
February1st to 10thNight
16%9%46%5%3445%7%38%
2340
11th to 20thNight
17%7%46%6%35%446%39%
2139
21st to endNight
19%7%345%345%5%5%40%
1776
March1st to 10thNight
17%5%25%43446%7%44%
2150
11th to 20thNight
18%8%25%434445%43%
1997
21st to endNight
17%7%346%35%447%40%
2039
April1st to 10thNight
18%6%36%5%35%5%5%8%37%
1800
11th to 20thNight
17%6%36%5%3446%7%40%
1775
21st to endNight
21%6%2442435%7%42%
1800
May1st to 10thNight
21%9%36%5%45%45%7%33%
1623
11th to 20thNight
18%6%35%425%5%5%7%39%
1415
21st to endNight
15%5%35%5%35%5%5%8%41%
1550
June1st to 10thNight
16%6%25%5%35%5%48%42%
1440
11th to 20thNight
14%5%35%5%345%7%9%40%
1440
21st to endNight
11%425%5%345%6%10%45%
1440
July1st to 10thNight
11%6%25%6%36%6%6%10%39%
1440
11th to 20thNight
10%5%25%5%36%6%7%9%43%
1440
21st to endNight
10%5%25%6%246%7%11%41%
1574
August1st to 10thNight
11%5%26%6%35%7%7%8%40%
1598
11th to 20thNight
11%7%36%6%5%5%5%7%8%37%
1748
21st to endNight
14%6%25%5%45%5%6%9%41%
1980
September1st to 10thNight
16%6%25%5%3445%6%44%
1800
11th to 20thNight
13%5%2443335%7%51%
1837
21st to endNight
17%5%35%42445%6%45%
1980
October1st to 10thNight
21%6%35%423447%42%
2142
11th to 20thNight
18%5%2443345%6%46%
2160
21st to endNight
22%6%24423446%43%
2466
November1st to 10thNight
13%5%243235%5%6%51%
2407
11th to 20thNight
17%7%34324346%46%
2470
21st to endNight
14%5%35%5%345%5%7%43%
2603
December1st to 10thNight
20%7%35%435%45%6%37%
2660
11th to 20thNight
18%7%245%346%5%7%39%
3288
21st to endNight
20%10%47%5%34446%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
44%412%25%12%3
1518
11th to 20thDay
51%5%12%19%10%3
1480
21st to endDay
45%5%10%24%14%2
1778
February1st to 10thDay
47%414%21%11%2
1620
11th to 20thDay
46%5%10%23%14%3
1714
21st to endDay
51%310%21%11%3
1480
March1st to 10thDay
41%5%12%26%14%3
1800
11th to 20thDay
45%5%11%21%16%2
1957
21st to endDay
47%49%18%17%4
2316
April1st to 10thDay
46%5%9%21%15%5%
2160
11th to 20thDay
43%5%10%21%17%4
2134
21st to endDay
45%6%9%20%16%5%
2160
May1st to 10thDay
50%6%8%17%16%3
2349
11th to 20thDay
47%6%10%20%14%3
2482
21st to endDay
41%8%13%22%14%2
2725
June1st to 10thDay
43%6%14%22%14%1
2520
11th to 20thDay
45%8%12%21%11%2
2520
21st to endDay
42%7%12%24%15%1
2520
July1st to 10thDay
43%8%10%22%16%1
2450
11th to 20thDay
35%7%15%26%15%2
2445
21st to endDay
43%7%11%20%16%3
2591
August1st to 10thDay
41%8%13%22%14%1
2323
11th to 20thDay
41%7%13%24%13%1
2134
21st to endDay
41%7%10%20%18%3
2376
September1st to 10thDay
41%7%10%21%18%3
2160
11th to 20thDay
34%5%10%23%25%4
2122
21st to endDay
44%5%8%19%21%2
1980
October1st to 10thDay
43%6%11%21%16%2
1816
11th to 20thDay
41%5%10%24%19%1
1800
21st to endDay
45%49%24%16%2
1888
November1st to 10thDay
37%312%24%20%3
1671
11th to 20thDay
40%410%24%19%3
1710
21st to endDay
41%314%28%11%2
1573
December1st to 10thDay
48%415%19%12%1
1520
11th to 20thDay
45%5%15%23%11%1
1906
21st to endDay
54%6%11%21%8%
2772
January1st to 10thNight
41%412%25%15%3
2649
11th to 20thNight
47%414%23%10%2
2602
21st to endNight
41%410%24%18%3
2574
February1st to 10thNight
46%413%23%12%2
2340
11th to 20thNight
47%5%9%19%16%4
2141
21st to endNight
45%38%24%17%3
1776
March1st to 10thNight
38%5%13%25%15%4
2160
11th to 20thNight
44%49%21%19%3
1998
21st to endNight
44%5%9%18%19%5%
2039
April1st to 10thNight
46%5%11%20%15%4
1800
11th to 20thNight
43%5%9%20%20%2
1775
21st to endNight
41%5%10%22%18%5%
1800
May1st to 10thNight
51%5%10%16%16%2
1623
11th to 20thNight
45%7%11%17%18%3
1416
21st to endNight
41%9%15%20%13%3
1551
June1st to 10thNight
41%6%11%22%19%1
1440
11th to 20thNight
40%8%15%23%13%1
1440
21st to endNight
33%9%14%27%15%1
1440
July1st to 10thNight
40%9%15%20%14%2
1400
11th to 20thNight
36%9%14%27%13%1
1392
21st to endNight
33%10%16%22%16%3
1486
August1st to 10thNight
38%10%14%21%16%2
1588
11th to 20thNight
42%8%15%20%13%1
1748
21st to endNight
38%8%11%20%20%2
1980
September1st to 10thNight
42%6%10%22%19%2
1800
11th to 20thNight
35%5%10%22%26%4
1837
21st to endNight
40%5%7%24%23%2
1980
October1st to 10thNight
44%5%10%24%14%2
2142
11th to 20thNight
38%5%12%28%16%2
2160
21st to endNight
42%410%26%16%1
2466
November1st to 10thNight
35%5%12%24%21%4
2407
11th to 20thNight
41%39%24%19%4
2470
21st to endNight
39%5%13%28%14%1
2603
December1st to 10thNight
46%5%12%23%12%1
2660
11th to 20thNight
43%5%13%20%16%3
3288
21st to endNight
50%5%12%23%10%
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
27%27%34%10%21
180
11th to 20thDay
29%32%27%10%1
170
21st to endDay
21%33%34%6%5%
262
February1st to 10thDay
28%34%29%6%3
240
11th to 20thDay
28%28%35%8%1
373
21st to endDay
34%26%26%12%2
346
March1st to 10thDay
24%29%30%14%3
420
11th to 20thDay
26%28%30%13%31
420
21st to endDay
30%24%30%10%5%1
462
April1st to 10thDay
26%25%29%15%5%1
420
11th to 20thDay
23%24%30%13%8%1
412
21st to endDay
27%21%35%13%31
420
May1st to 10thDay
31%22%29%11%7%1
423
11th to 20thDay
22%18%35%19%5%1
447
21st to endDay
21%10%27%27%13%2
485
June1st to 10thDay
18%17%29%22%12%2
450
11th to 20thDay
17%16%30%23%12%1
450
21st to endDay
15%14%32%25%12%2
450
July1st to 10thDay
13%7%27%29%18%6%
445
11th to 20thDay
12%5%26%35%18%3
444
21st to endDay
16%7%33%29%13%3
488
August1st to 10thDay
12%6%29%30%17%6%
446
11th to 20thDay
15%5%27%30%19%5%
439
21st to endDay
13%8%30%27%14%7%
495
September1st to 10thDay
20%10%24%27%13%6%
450
11th to 20thDay
14%7%31%23%14%10%
450
21st to endDay
21%12%30%21%11%5%
450
October1st to 10thDay
26%10%28%19%13%5%
450
11th to 20thDay
17%19%31%22%9%2
450
21st to endDay
24%19%32%15%9%1
448
November1st to 10thDay
19%18%27%22%11%3
365
11th to 20thDay
24%22%31%18%41
370
21st to endDay
21%23%38%14%4
233
December1st to 10thDay
26%32%28%9%6%
180
11th to 20thDay
33%28%24%12%3
180
21st to endDay
29%22%29%15%5%1
198
January1st to 10thNight
20%26%37%14%3
760
11th to 20thNight
26%21%30%20%2
744
21st to endNight
18%25%37%18%1
792
February1st to 10thNight
23%22%37%17%2
720
11th to 20thNight
23%27%37%12%1
703
21st to endNight
26%24%31%17%2
592
March1st to 10thNight
24%24%30%19%3
720
11th to 20thNight
23%23%33%17%3
720
21st to endNight
21%22%37%15%5%1
792
April1st to 10thNight
20%25%34%17%4
720
11th to 20thNight
21%18%36%19%6%
711
21st to endNight
23%16%33%23%5%
720
May1st to 10thNight
26%18%28%22%6%
543
11th to 20thNight
22%10%38%22%7%
354
21st to endNight
19%6%26%36%13%1
389
June1st to 10thNight
18%8%29%32%13%1
360
11th to 20thNight
14%8%32%35%11%
360
21st to endNight
12%329%44%12%1
360
July1st to 10thNight
13%426%37%18%2
350
11th to 20thNight
11%326%40%19%1
348
21st to endNight
13%5%26%38%16%1
394
August1st to 10thNight
13%119%42%22%2
524
11th to 20thNight
14%320%36%24%2
684
21st to endNight
14%5%22%35%22%2
792
September1st to 10thNight
20%5%26%32%15%2
720
11th to 20thNight
16%5%23%32%20%4
720
21st to endNight
22%6%25%31%14%2
720
October1st to 10thNight
23%9%25%26%14%2
720
11th to 20thNight
19%12%29%30%10%
720
21st to endNight
25%16%29%22%8%
792
November1st to 10thNight
17%16%31%26%9%1
740
11th to 20thNight
22%20%29%22%6%1
760
21st to endNight
18%20%35%21%5%1
760
December1st to 10thNight
26%21%31%18%4
760
11th to 20thNight
21%23%33%20%3
760
21st to endNight
22%23%33%20%2
836
Page generated at 2024-01-13 09:37:58. Version ac07

Copyright 2024 Attilla Danko


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