This page made possible by the sponsorship of: Joseph Trerotola.

Joes Universe
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Joes Universe clear sky chart from 2005-11-06 to 2024-01-15.

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
29%
23057
19%
74641
8%
23016
41%
23016
21%
48188

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
18%
760
23%
2649
7%
757
38%
757
20%
1586
January11th to 20thNight
19%
740
19%
2588
6%
740
35%
740
14%
1710
January21st to endNight
18%
792
22%
2714
6%
792
39%
792
20%
1640
February1st to 10thNight
17%
720
17%
2284
5%
720
32%
720
16%
1529
February11th to 20thNight
15%
703
20%
2100
4%
700
33%
700
19%
1384
February21st to endNight
15%
592
24%
1776
8%
592
34%
592
18%
1176
March1st to 10thNight
20%
720
21%
2160
7%
720
37%
720
21%
1363
March11th to 20thNight
20%
720
19%
2106
6%
720
34%
720
20%
1405
March21st to endNight
18%
792
22%
1980
5%
792
31%
792
22%
1357
April1st to 10thNight
22%
720
18%
1800
4%
720
30%
720
21%
1270
April11th to 20thNight
26%
711
17%
1775
4%
711
33%
711
26%
1234
April21st to endNight
22%
630
18%
1710
4%
630
32%
630
22%
1190
May1st to 10thNight
26%
540
14%
1620
5%
540
33%
540
16%
1179
May11th to 20thNight
23%
438
18%
1500
9%
438
33%
438
18%
997
May21st to endNight
40%
388
13%
1551
12%
388
47%
388
18%
990
June1st to 10thNight
36%
360
15%
1440
13%
360
46%
360
18%
928
June11th to 20thNight
42%
360
13%
1440
14%
360
49%
360
20%
898
June21st to endNight
48%
360
15%
1440
14%
360
57%
360
22%
858
July1st to 10thNight
50%
350
13%
1400
15%
350
55%
350
20%
877
July11th to 20thNight
55%
348
12%
1392
15%
348
59%
348
20%
864
July21st to endNight
53%
394
17%
1486
18%
372
59%
372
23%
877
August1st to 10thNight
50%
423
16%
1487
12%
421
56%
421
25%
910
August11th to 20thNight
51%
705
13%
1769
6%
705
53%
705
25%
1258
August21st to endNight
50%
792
18%
1980
9%
792
53%
792
33%
1303
September1st to 10thNight
43%
720
21%
1800
9%
720
48%
720
30%
1224
September11th to 20thNight
47%
720
24%
1917
15%
720
52%
720
34%
1182
September21st to endNight
42%
720
23%
1980
15%
720
50%
720
26%
1329
October1st to 10thNight
35%
720
16%
2012
10%
720
42%
720
23%
1377
October11th to 20thNight
34%
720
23%
2166
11%
720
49%
720
26%
1357
October21st to endNight
23%
792
18%
2574
8%
792
36%
792
20%
1702
November1st to 10thNight
32%
740
23%
2407
12%
740
47%
740
25%
1435
November11th to 20thNight
24%
760
24%
2470
10%
760
42%
760
22%
1516
November21st to endNight
25%
760
22%
2499
8%
760
41%
760
21%
1523
December1st to 10thNight
20%
760
19%
2660
6%
760
36%
760
16%
1720
December11th to 20thNight
20%
760
17%
3188
5%
759
35%
759
13%
1984
December21st to endNight
17%
827
13%
4821
5%
817
35%
817
10%
3056

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%345%5%7%40%
74804
Night
18%7%35%43445%6%42%
74975
TransparencyDay
42%7%12%22%15%2
74509
Night
42%6%12%22%15%2
74804
SeeingDay
20%16%31%22%9%2
13894
Night
21%13%32%25%8%1
23067

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%6%25%3345%6%6%44%
1517
11th to 20thDay
17%8%36%436%5%5%7%36%
1478
21st to endDay
14%7%35%4245%5%7%42%
1638
February1st to 10thDay
18%7%36%5%36%45%7%36%
1674
11th to 20thDay
16%6%35%43447%7%41%
1748
21st to endDay
22%8%36%4235%46%36%
1480
March1st to 10thDay
16%7%35%5%3445%7%41%
1797
11th to 20thDay
17%6%35%435%5%6%7%39%
1852
21st to endDay
20%8%46%5%34335%40%
2376
April1st to 10thDay
19%8%25%5%3436%7%39%
2160
11th to 20thDay
19%5%24433447%43%
2134
21st to endDay
23%5%2443445%5%40%
2250
May1st to 10thDay
25%7%245%3445%8%34%
2340
11th to 20thDay
19%6%345%35%45%7%39%
2409
21st to endDay
17%5%25%4345%6%7%43%
2725
June1st to 10thDay
19%5%25%6%35%6%6%8%35%
2520
11th to 20thDay
17%7%35%435%5%6%10%35%
2520
21st to endDay
14%6%35%6%35%5%6%9%39%
2520
July1st to 10thDay
13%5%25%445%6%6%8%40%
2520
11th to 20thDay
13%4345%35%6%7%10%40%
2520
21st to endDay
13%5%26%5%46%6%6%9%38%
2744
August1st to 10thDay
13%5%26%6%36%6%7%9%38%
2422
11th to 20thDay
13%5%35%5%35%5%6%9%41%
2128
21st to endDay
12%6%35%5%35%5%6%8%42%
2376
September1st to 10thDay
14%6%25%5%35%45%7%43%
2160
11th to 20thDay
14%425%424446%51%
2041
21st to endDay
19%6%25%5%24446%43%
1980
October1st to 10thDay
23%6%25%433446%41%
1944
11th to 20thDay
16%5%3443445%8%45%
1793
21st to endDay
21%6%25%4345%5%6%39%
1782
November1st to 10thDay
14%6%25%5%3335%6%48%
1671
11th to 20thDay
20%5%25%22345%6%46%
1710
21st to endDay
18%5%3443446%7%43%
1677
December1st to 10thDay
20%6%25%5%345%5%7%38%
1520
11th to 20thDay
23%6%24423346%44%
1906
21st to endDay
19%11%46%5%3445%6%33%
2772
January1st to 10thNight
16%6%25%42445%6%46%
2649
11th to 20thNight
21%7%35%43445%5%39%
2588
21st to endNight
15%8%35%42445%6%45%
2714
February1st to 10thNight
18%10%35%5%34445%40%
2284
11th to 20thNight
17%8%35%5%34347%40%
2098
21st to endNight
20%7%36%434435%41%
1776
March1st to 10thNight
17%7%2433445%6%44%
2150
11th to 20thNight
16%7%35%5%345%5%7%40%
2105
21st to endNight
18%7%35%32435%6%42%
1980
April1st to 10thNight
19%8%35%43445%7%38%
1800
11th to 20thNight
19%5%35%5%2445%6%42%
1775
21st to endNight
21%7%35%6%24345%41%
1710
May1st to 10thNight
23%7%35%6%345%5%6%33%
1620
11th to 20thNight
20%7%35%5%34447%38%
1499
21st to endNight
18%7%35%43445%7%40%
1550
June1st to 10thNight
19%5%36%5%3445%6%39%
1440
11th to 20thNight
17%6%35%5%2446%9%40%
1440
21st to endNight
13%7%25%5%35%45%9%43%
1440
July1st to 10thNight
14%5%346%35%5%7%9%40%
1440
11th to 20thNight
14%5%35%6%36%5%7%8%38%
1440
21st to endNight
13%425%5%35%6%7%9%40%
1574
August1st to 10thNight
9%6%25%6%35%6%7%8%43%
1497
11th to 20thNight
12%7%36%7%36%5%6%6%38%
1769
21st to endNight
14%6%245%25%45%8%45%
1980
September1st to 10thNight
14%7%26%5%35%447%44%
1800
11th to 20thNight
15%5%24323346%52%
1917
21st to endNight
17%6%35%334345%45%
1980
October1st to 10thNight
21%6%25%434445%41%
2012
11th to 20thNight
16%5%25%424445%47%
2166
21st to endNight
23%7%25%424345%41%
2574
November1st to 10thNight
13%6%245%34446%49%
2407
11th to 20thNight
20%5%25%333336%46%
2470
21st to endNight
17%5%245%33446%47%
2499
December1st to 10thNight
21%7%34434446%40%
2660
11th to 20thNight
21%6%24435%446%41%
3288
21st to endNight
22%11%36%424345%36%
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
39%6%11%28%13%4
1518
11th to 20thDay
45%8%14%18%13%2
1478
21st to endDay
40%6%11%24%16%3
1638
February1st to 10thDay
47%5%14%19%13%2
1674
11th to 20thDay
40%6%12%23%17%3
1757
21st to endDay
48%6%11%20%13%3
1480
March1st to 10thDay
42%5%14%21%14%4
1800
11th to 20thDay
43%6%13%21%15%2
1852
21st to endDay
48%47%18%18%5%
2376
April1st to 10thDay
44%5%10%20%16%4
2160
11th to 20thDay
42%6%11%21%18%3
2134
21st to endDay
45%5%10%20%16%4
2250
May1st to 10thDay
48%7%9%20%13%3
2340
11th to 20thDay
43%6%11%20%17%3
2413
21st to endDay
39%9%17%20%14%2
2725
June1st to 10thDay
44%8%12%23%11%1
2520
11th to 20thDay
43%9%13%22%12%1
2520
21st to endDay
40%9%14%24%13%1
2520
July1st to 10thDay
39%10%12%21%17%1
2450
11th to 20thDay
37%9%15%24%13%2
2445
21st to endDay
39%9%13%20%16%2
2591
August1st to 10thDay
38%10%16%23%13%1
2408
11th to 20thDay
39%8%17%23%13%1
2128
21st to endDay
38%7%13%22%18%2
2376
September1st to 10thDay
40%8%12%21%18%2
2160
11th to 20thDay
34%6%11%23%24%2
2041
21st to endDay
42%6%10%21%19%3
1980
October1st to 10thDay
45%7%9%21%16%3
1944
11th to 20thDay
36%6%14%26%16%2
1793
21st to endDay
45%6%10%21%16%3
1782
November1st to 10thDay
38%5%12%23%19%3
1671
11th to 20thDay
39%411%22%20%3
1710
21st to endDay
40%414%26%12%3
1677
December1st to 10thDay
46%6%16%17%14%1
1520
11th to 20thDay
42%317%19%17%2
1906
21st to endDay
51%6%11%22%9%1
2772
January1st to 10thNight
39%412%25%16%4
2649
11th to 20thNight
46%6%13%22%11%2
2588
21st to endNight
40%412%23%19%3
2714
February1st to 10thNight
47%5%12%21%13%2
2284
11th to 20thNight
44%411%20%16%4
2100
21st to endNight
46%48%23%15%4
1776
March1st to 10thNight
39%5%13%23%16%4
2160
11th to 20thNight
43%6%10%21%15%4
2106
21st to endNight
43%5%10%18%20%5%
1980
April1st to 10thNight
45%6%11%20%15%3
1800
11th to 20thNight
43%5%11%19%20%1
1775
21st to endNight
46%5%9%21%15%5%
1710
May1st to 10thNight
51%8%9%16%15%2
1620
11th to 20thNight
47%6%10%17%17%2
1500
21st to endNight
44%7%16%20%12%1
1551
June1st to 10thNight
45%7%11%19%17%2
1440
11th to 20thNight
41%8%15%24%11%1
1440
21st to endNight
38%8%13%25%15%1
1440
July1st to 10thNight
39%10%14%20%14%2
1400
11th to 20thNight
40%9%15%26%9%1
1392
21st to endNight
36%9%16%22%14%3
1486
August1st to 10thNight
35%10%15%23%14%1
1487
11th to 20thNight
43%9%14%23%10%1
1769
21st to endNight
35%8%15%22%18%1
1980
September1st to 10thNight
41%6%10%25%16%2
1800
11th to 20thNight
34%6%10%22%25%3
1917
21st to endNight
42%7%7%21%21%3
1980
October1st to 10thNight
45%6%11%21%14%3
2012
11th to 20thNight
38%6%12%28%15%1
2166
21st to endNight
46%5%12%20%15%1
2574
November1st to 10thNight
37%5%12%22%20%4
2407
11th to 20thNight
41%410%23%18%4
2470
21st to endNight
39%413%29%12%2
2499
December1st to 10thNight
45%5%13%21%14%1
2660
11th to 20thNight
44%5%13%18%17%2
3288
21st to endNight
49%5%12%22%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
23%28%28%19%2
180
11th to 20thDay
19%34%31%15%11
170
21st to endDay
20%29%36%11%41
200
February1st to 10thDay
29%25%34%11%1
294
11th to 20thDay
22%27%37%13%1
416
21st to endDay
27%26%32%13%3
346
March1st to 10thDay
19%25%38%15%3
420
11th to 20thDay
20%26%36%14%31
420
21st to endDay
25%23%36%12%41
462
April1st to 10thDay
23%25%32%13%6%1
420
11th to 20thDay
25%20%33%15%6%1
412
21st to endDay
28%18%34%14%5%1
420
May1st to 10thDay
29%20%32%13%6%1
423
11th to 20thDay
21%15%38%20%6%1
447
21st to endDay
19%10%28%29%11%3
485
June1st to 10thDay
19%12%29%27%11%3
450
11th to 20thDay
16%12%32%28%11%1
450
21st to endDay
14%8%36%29%12%2
450
July1st to 10thDay
15%5%29%30%18%3
445
11th to 20thDay
14%5%26%32%20%3
444
21st to endDay
12%7%32%36%11%1
488
August1st to 10thDay
13%6%25%38%12%5%
446
11th to 20thDay
15%425%33%16%6%
439
21st to endDay
11%9%31%26%16%6%
495
September1st to 10thDay
16%10%27%24%19%4
450
11th to 20thDay
16%8%30%26%13%8%
450
21st to endDay
20%11%32%24%11%3
450
October1st to 10thDay
27%10%26%21%13%4
450
11th to 20thDay
16%19%29%25%10%1
446
21st to endDay
25%16%32%19%7%1
396
November1st to 10thDay
16%14%30%25%12%2
365
11th to 20thDay
23%23%28%21%5%
370
21st to endDay
20%20%32%21%6%
337
December1st to 10thDay
24%18%36%17%5%
180
11th to 20thDay
29%26%29%14%2
180
21st to endDay
21%23%34%17%5%1
198
January1st to 10thNight
21%20%37%19%3
760
11th to 20thNight
26%19%33%19%3
740
21st to endNight
20%19%39%19%3
792
February1st to 10thNight
23%19%36%20%2
720
11th to 20thNight
24%21%37%17%2
703
21st to endNight
24%21%36%17%2
592
March1st to 10thNight
23%19%35%20%3
720
11th to 20thNight
21%16%39%20%31
720
21st to endNight
22%18%38%18%4
792
April1st to 10thNight
23%18%34%20%4
720
11th to 20thNight
21%14%36%24%4
711
21st to endNight
22%16%35%21%5%1
630
May1st to 10thNight
27%11%33%23%7%
540
11th to 20thNight
23%12%38%23%5%
438
21st to endNight
22%6%23%38%10%1
389
June1st to 10thNight
20%6%31%32%11%1
360
11th to 20thNight
18%6%28%36%13%
360
21st to endNight
16%326%44%11%
360
July1st to 10thNight
14%423%40%19%1
350
11th to 20thNight
14%320%45%17%2
348
21st to endNight
13%324%45%14%1
394
August1st to 10thNight
9%330%41%16%1
423
11th to 20thNight
16%320%39%19%2
705
21st to endNight
14%5%22%37%19%3
792
September1st to 10thNight
18%5%27%34%15%2
720
11th to 20thNight
18%6%24%31%17%3
720
21st to endNight
20%7%25%31%15%1
720
October1st to 10thNight
23%10%29%25%13%2
720
11th to 20thNight
18%12%32%28%9%
720
21st to endNight
27%12%35%20%7%
792
November1st to 10thNight
16%13%33%26%10%1
740
11th to 20thNight
22%16%35%20%6%1
760
21st to endNight
21%18%33%24%5%1
760
December1st to 10thNight
26%16%33%19%5%1
760
11th to 20thNight
23%19%33%21%3
760
21st to endNight
25%18%35%19%2
836
Page generated at 2024-01-12 16:17:42. Version ac07

Copyright 2024 Attilla Danko


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