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Edwelda Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Edwelda Observatory clear sky chart from 2005-11-06 to 2024-03-06.

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
26%
23128
19%
80531
8%
23037
39%
23037
19%
51886

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
16%
751
23%
4329
5%
737
35%
737
12%
2324
January11th to 20thNight
14%
759
23%
4345
4%
740
30%
740
9%
2600
January21st to endNight
16%
830
12%
4862
5%
814
34%
814
8%
3398
February1st to 10thNight
18%
760
18%
2406
5%
760
34%
760
17%
1601
February11th to 20thNight
14%
743
21%
2220
5%
740
33%
740
19%
1474
February21st to endNight
20%
628
24%
1884
8%
628
39%
628
19%
1241
March1st to 10thNight
20%
743
21%
2227
8%
743
37%
743
19%
1497
March11th to 20thNight
17%
720
19%
2057
5%
720
31%
720
18%
1423
March21st to endNight
20%
792
21%
2066
6%
792
32%
792
20%
1445
April1st to 10thNight
21%
720
19%
1800
4%
720
30%
720
20%
1274
April11th to 20thNight
22%
689
17%
1753
4%
689
30%
689
22%
1215
April21st to endNight
20%
540
19%
1620
5%
540
31%
540
18%
1099
May1st to 10thNight
21%
540
13%
1620
5%
540
27%
540
15%
1170
May11th to 20thNight
20%
518
17%
1580
8%
518
30%
518
19%
1050
May21st to endNight
32%
389
13%
1551
11%
388
40%
388
17%
969
June1st to 10thNight
30%
360
13%
1440
9%
360
43%
360
16%
946
June11th to 20thNight
31%
360
13%
1440
12%
360
41%
360
18%
918
June21st to endNight
36%
360
13%
1440
9%
360
47%
360
21%
878
July1st to 10thNight
41%
350
13%
1400
13%
350
50%
350
21%
837
July11th to 20thNight
42%
348
13%
1392
13%
348
48%
348
20%
858
July21st to endNight
44%
394
19%
1486
16%
372
54%
372
23%
888
August1st to 10thNight
45%
497
17%
1561
11%
495
50%
495
29%
947
August11th to 20thNight
43%
543
18%
1607
11%
543
47%
543
24%
1077
August21st to endNight
50%
792
21%
1980
10%
792
53%
792
34%
1288
September1st to 10thNight
40%
720
21%
1808
8%
720
47%
720
32%
1187
September11th to 20thNight
44%
720
25%
1980
14%
720
52%
720
33%
1201
September21st to endNight
38%
720
24%
1980
15%
720
47%
720
29%
1298
October1st to 10thNight
33%
720
18%
1980
10%
720
41%
720
23%
1336
October11th to 20thNight
33%
720
22%
2199
10%
720
47%
720
26%
1366
October21st to endNight
22%
792
16%
2574
6%
792
36%
792
18%
1731
November1st to 10thNight
30%
740
23%
2407
11%
740
45%
740
23%
1461
November11th to 20thNight
23%
760
24%
2470
9%
760
42%
760
21%
1539
November21st to endNight
21%
760
22%
2470
7%
760
39%
760
19%
1538
December1st to 10thNight
18%
760
19%
2617
6%
760
33%
760
16%
1721
December11th to 20thNight
21%
760
18%
3192
4%
759
37%
759
13%
1982
December21st to endNight
17%
830
15%
4788
5%
817
36%
817
9%
3109

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
17%6%35%5%35%5%5%7%40%
78396
Night
17%7%35%5%3445%6%41%
81112
TransparencyDay
44%5%11%22%15%3
78101
Night
45%5%11%22%15%2
80941
SeeingDay
24%16%33%19%7%2
14096
Night
22%13%34%24%7%1
23150

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
15%7%26%424446%45%
2517
11th to 20thDay
17%6%36%5%345%5%5%41%
2520
21st to endDay
21%10%45%5%345%5%5%34%
2772
February1st to 10thDay
19%8%25%426%6%5%6%36%
1766
11th to 20thDay
14%7%36%425%6%6%6%40%
1848
21st to endDay
18%8%36%6%4445%5%37%
1570
March1st to 10thDay
18%7%345%35%5%48%38%
1847
11th to 20thDay
17%6%26%5%25%5%6%7%39%
1901
21st to endDay
19%8%26%5%2435%5%40%
2286
April1st to 10thDay
19%8%35%5%3445%6%37%
2160
11th to 20thDay
18%6%34445%5%48%38%
2156
21st to endDay
21%6%26%6%35%45%7%35%
2340
May1st to 10thDay
24%8%36%5%35%447%31%
2340
11th to 20thDay
17%6%36%5%35%45%7%39%
2329
21st to endDay
15%5%245%4445%8%44%
2725
June1st to 10thDay
20%6%25%5%35%6%6%9%34%
2520
11th to 20thDay
16%6%35%445%5%6%8%38%
2520
21st to endDay
18%5%35%6%35%5%7%9%34%
2520
July1st to 10thDay
13%6%26%5%45%5%6%8%41%
2520
11th to 20thDay
12%5%36%6%45%6%6%9%40%
2520
21st to endDay
12%5%25%5%46%6%6%9%41%
2744
August1st to 10thDay
10%6%26%6%36%6%6%10%38%
2350
11th to 20thDay
13%5%35%5%46%6%6%8%39%
2289
21st to endDay
12%5%25%435%46%8%45%
2376
September1st to 10thDay
14%5%244345%5%8%45%
2152
11th to 20thDay
15%6%24423446%51%
1980
21st to endDay
17%5%25%5%2345%6%46%
1980
October1st to 10thDay
23%5%25%434446%40%
1980
11th to 20thDay
15%5%2444445%7%46%
1759
21st to endDay
21%6%25%43445%6%39%
1782
November1st to 10thDay
16%6%245%23336%49%
1671
11th to 20thDay
19%6%24424346%46%
1710
21st to endDay
18%6%35%334446%44%
1710
December1st to 10thDay
18%7%35%5%35%446%40%
1558
11th to 20thDay
22%7%24324335%44%
1906
21st to endDay
21%10%35%5%35%446%34%
2772
January1st to 10thNight
18%8%24323336%47%
4429
11th to 20thNight
15%8%37%6%34445%40%
4440
21st to endNight
21%13%46%5%34445%31%
4884
February1st to 10thNight
17%9%35%5%345%5%6%38%
2406
11th to 20thNight
15%8%46%5%2445%6%41%
2218
21st to endNight
18%9%25%42445%6%42%
1884
March1st to 10thNight
17%7%36%5%3445%6%40%
2217
11th to 20thNight
16%8%36%6%35%5%45%38%
2057
21st to endNight
19%9%345%34435%42%
2066
April1st to 10thNight
19%7%26%5%3446%6%37%
1800
11th to 20thNight
21%6%25%42445%6%41%
1753
21st to endNight
22%6%26%5%34445%38%
1620
May1st to 10thNight
23%8%36%5%35%45%6%32%
1620
11th to 20thNight
19%6%25%435%6%6%8%36%
1579
21st to endNight
17%8%35%4345%5%7%39%
1550
June1st to 10thNight
18%8%36%5%345%5%5%37%
1440
11th to 20thNight
18%7%35%5%35%46%8%36%
1440
21st to endNight
14%5%345%346%7%9%40%
1440
July1st to 10thNight
14%5%35%5%35%46%8%41%
1440
11th to 20thNight
12%8%36%5%46%5%5%9%37%
1440
21st to endNight
13%5%35%435%5%6%9%42%
1574
August1st to 10thNight
9%425%6%35%5%6%9%45%
1571
11th to 20thNight
10%6%26%7%46%7%7%7%38%
1607
21st to endNight
14%4244345%5%8%47%
1980
September1st to 10thNight
14%5%25%5%2445%7%46%
1808
11th to 20thNight
14%5%24323346%54%
1980
21st to endNight
17%5%25%5%3445%6%45%
1980
October1st to 10thNight
22%5%345%34346%41%
1980
11th to 20thNight
15%5%244245%47%46%
2199
21st to endNight
22%7%35%433447%38%
2574
November1st to 10thNight
15%425%5%2445%6%48%
2407
11th to 20thNight
19%6%25%324345%46%
2470
21st to endNight
16%7%24425%447%44%
2470
December1st to 10thNight
19%8%36%5%34446%39%
2617
11th to 20thNight
20%7%244245%5%6%42%
3288
21st to endNight
20%10%36%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
41%48%33%13%2
2518
11th to 20thDay
45%6%9%25%14%2
2520
21st to endDay
51%410%23%10%2
2772
February1st to 10thDay
48%411%20%14%3
1766
11th to 20thDay
44%6%11%22%15%3
1857
21st to endDay
49%410%20%14%3
1570
March1st to 10thDay
45%5%12%21%13%4
1850
11th to 20thDay
45%5%10%20%16%4
1901
21st to endDay
47%48%18%16%7%
2286
April1st to 10thDay
48%49%19%17%4
2160
11th to 20thDay
44%5%10%21%17%3
2156
21st to endDay
49%5%8%18%17%4
2340
May1st to 10thDay
54%47%20%13%2
2340
11th to 20thDay
44%6%10%18%19%4
2333
21st to endDay
39%6%13%24%14%2
2725
June1st to 10thDay
47%6%13%22%11%1
2520
11th to 20thDay
44%8%10%19%17%2
2520
21st to endDay
45%7%12%21%13%1
2520
July1st to 10thDay
40%6%11%24%16%3
2450
11th to 20thDay
40%6%13%26%14%1
2445
21st to endDay
39%7%13%23%14%4
2591
August1st to 10thDay
40%9%13%24%13%1
2336
11th to 20thDay
42%8%12%23%14%1
2289
21st to endDay
37%6%10%25%20%3
2376
September1st to 10thDay
38%6%11%24%20%2
2152
11th to 20thDay
36%48%27%23%2
1980
21st to endDay
40%39%23%23%3
1980
October1st to 10thDay
46%5%8%23%14%4
1980
11th to 20thDay
37%5%11%30%16%2
1759
21st to endDay
47%412%19%15%3
1782
November1st to 10thDay
40%312%26%17%3
1671
11th to 20thDay
41%39%23%21%2
1710
21st to endDay
42%5%14%23%14%2
1710
December1st to 10thDay
46%5%14%16%18%1
1558
11th to 20thDay
44%312%18%17%5%
1906
21st to endDay
52%5%10%21%11%1
2772
January1st to 10thNight
40%312%29%12%3
4429
11th to 20thNight
47%411%23%13%3
4440
21st to endNight
57%5%9%17%11%2
4884
February1st to 10thNight
47%5%12%21%14%3
2406
11th to 20thNight
45%410%21%16%4
2220
21st to endNight
45%48%24%15%4
1884
March1st to 10thNight
45%5%8%22%15%5%
2227
11th to 20thNight
48%410%17%17%4
2058
21st to endNight
47%47%17%20%6%
2066
April1st to 10thNight
47%410%18%17%3
1800
11th to 20thNight
45%5%9%20%18%3
1753
21st to endNight
48%410%18%15%4
1620
May1st to 10thNight
53%5%9%17%13%3
1620
11th to 20thNight
45%6%11%18%16%4
1580
21st to endNight
45%6%14%21%13%1
1551
June1st to 10thNight
48%7%12%22%11%1
1440
11th to 20thNight
45%6%12%20%15%2
1440
21st to endNight
40%8%14%23%14%1
1440
July1st to 10thNight
40%6%14%23%16%1
1400
11th to 20thNight
42%7%13%27%10%1
1392
21st to endNight
38%7%12%29%11%2
1486
August1st to 10thNight
35%7%16%25%15%2
1561
11th to 20thNight
41%9%15%21%14%
1607
21st to endNight
35%7%10%26%21%1
1980
September1st to 10thNight
38%5%11%25%19%2
1808
11th to 20thNight
34%410%23%27%2
1980
21st to endNight
39%6%7%24%22%3
1980
October1st to 10thNight
45%411%23%12%4
1980
11th to 20thNight
39%5%12%28%15%1
2199
21st to endNight
48%411%21%15%2
2574
November1st to 10thNight
39%5%11%22%20%4
2407
11th to 20thNight
42%39%23%19%3
2470
21st to endNight
41%413%26%14%2
2470
December1st to 10thNight
47%5%12%22%14%1
2617
11th to 20thNight
43%5%13%17%19%2
3288
21st to endNight
51%5%7%26%11%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
26%22%31%15%6%
180
11th to 20thDay
33%18%34%10%31
180
21st to endDay
25%23%35%13%5%
198
February1st to 10thDay
33%16%34%16%2
371
11th to 20thDay
26%23%36%13%2
456
21st to endDay
29%17%34%16%41
382
March1st to 10thDay
29%17%34%17%3
440
11th to 20thDay
28%21%34%12%41
420
21st to endDay
29%20%32%9%8%2
462
April1st to 10thDay
33%23%23%14%6%1
420
11th to 20thDay
28%24%32%10%6%
412
21st to endDay
30%19%33%14%31
420
May1st to 10thDay
34%22%28%12%31
423
11th to 20thDay
23%19%38%15%41
447
21st to endDay
19%13%38%21%7%1
485
June1st to 10thDay
22%14%38%18%8%2
450
11th to 20thDay
17%18%39%19%6%1
450
21st to endDay
16%16%36%23%8%2
450
July1st to 10thDay
18%10%32%27%11%2
445
11th to 20thDay
16%7%32%30%12%2
444
21st to endDay
14%7%38%31%9%1
488
August1st to 10thDay
12%9%33%33%11%2
446
11th to 20thDay
17%8%32%27%13%3
439
21st to endDay
16%9%33%26%14%3
495
September1st to 10thDay
19%9%30%24%15%3
450
11th to 20thDay
22%13%28%19%11%7%
450
21st to endDay
20%14%31%22%8%5%
450
October1st to 10thDay
28%13%24%20%10%3
450
11th to 20thDay
21%17%31%20%10%2
396
21st to endDay
27%15%31%18%8%1
396
November1st to 10thDay
23%13%34%19%10%2
365
11th to 20thDay
30%17%31%16%5%1
370
21st to endDay
28%19%29%18%6%1
370
December1st to 10thDay
23%23%35%16%3
218
11th to 20thDay
33%21%35%9%2
180
21st to endDay
25%21%35%13%32
198
January1st to 10thNight
22%17%39%18%3
760
11th to 20thNight
28%17%36%18%2
760
21st to endNight
21%18%37%21%4
836
February1st to 10thNight
23%16%39%21%1
760
11th to 20thNight
23%17%42%17%2
743
21st to endNight
26%17%34%20%3
628
March1st to 10thNight
25%16%36%20%3
743
11th to 20thNight
24%16%37%19%4
720
21st to endNight
26%16%33%20%5%
792
April1st to 10thNight
25%18%32%20%5%
720
11th to 20thNight
26%16%34%19%5%
689
21st to endNight
25%15%35%22%2
540
May1st to 10thNight
28%15%32%20%5%
540
11th to 20thNight
23%13%38%21%5%
518
21st to endNight
23%7%32%30%7%1
389
June1st to 10thNight
22%5%35%30%7%1
360
11th to 20thNight
19%7%37%32%6%1
360
21st to endNight
18%437%34%8%
360
July1st to 10thNight
15%432%37%11%1
350
11th to 20thNight
14%431%36%15%
348
21st to endNight
14%431%40%10%1
394
August1st to 10thNight
11%433%40%11%1
497
11th to 20thNight
12%7%30%38%14%
543
21st to endNight
17%424%39%15%2
792
September1st to 10thNight
17%5%32%32%14%1
720
11th to 20thNight
17%7%28%28%17%2
720
21st to endNight
20%7%29%29%13%2
720
October1st to 10thNight
25%10%26%26%12%2
720
11th to 20thNight
19%10%34%24%12%1
720
21st to endNight
28%12%32%21%6%
792
November1st to 10thNight
18%13%33%26%8%1
740
11th to 20thNight
24%16%34%19%7%
760
21st to endNight
23%18%33%20%5%1
760
December1st to 10thNight
26%17%35%19%4
760
11th to 20thNight
25%17%32%22%4
760
21st to endNight
26%15%36%21%2
836
Page generated at 2024-03-03 06:28:55. Version ac07

Copyright © 2024 Attilla Danko.


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