Leon Observing Site
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Leon Observing Site 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
39%
24002
18%
74578
12%
23954
46%
23954
21%
50925

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
19%
758
13%
2459
6%
757
27%
757
11%
1889
January11th to 20thNight
18%
737
12%
2393
6%
737
26%
737
10%
1844
January21st to endNight
19%
792
14%
2574
6%
792
29%
792
13%
1902
February1st to 10thNight
24%
720
12%
2340
7%
720
30%
720
13%
1752
February11th to 20thNight
16%
700
12%
2144
5%
700
23%
700
12%
1621
February21st to endNight
16%
592
15%
1776
5%
592
26%
592
13%
1345
March1st to 10thNight
25%
720
20%
2026
10%
720
34%
720
19%
1416
March11th to 20thNight
25%
720
16%
1980
8%
720
32%
720
18%
1431
March21st to endNight
28%
792
15%
2178
8%
792
34%
792
18%
1577
April1st to 10thNight
28%
720
18%
1980
8%
720
36%
720
23%
1343
April11th to 20thNight
36%
600
21%
1677
11%
600
44%
600
27%
1109
April21st to endNight
31%
540
19%
1620
7%
540
41%
540
22%
1101
May1st to 10thNight
37%
540
15%
1620
8%
540
42%
540
20%
1135
May11th to 20thNight
38%
531
15%
1593
9%
531
44%
531
19%
1134
May21st to endNight
56%
582
17%
1745
12%
582
60%
582
29%
1112
June1st to 10thNight
58%
540
17%
1620
16%
540
60%
540
31%
1000
June11th to 20thNight
56%
540
15%
1620
12%
540
59%
540
29%
1027
June21st to endNight
59%
540
17%
1620
15%
540
61%
540
30%
993
July1st to 10thNight
63%
525
14%
1575
14%
525
64%
525
28%
1021
July11th to 20thNight
67%
522
17%
1566
14%
522
69%
522
31%
951
July21st to endNight
64%
591
18%
1672
16%
558
66%
558
29%
1063
August1st to 10thNight
65%
537
19%
1600
17%
534
66%
534
28%
1035
August11th to 20thNight
65%
534
22%
1598
19%
534
67%
534
28%
1025
August21st to endNight
66%
630
24%
1818
20%
630
68%
630
35%
1080
September1st to 10thNight
64%
720
22%
1966
16%
720
67%
720
35%
1225
September11th to 20thNight
63%
720
27%
1980
21%
720
67%
720
37%
1181
September21st to endNight
50%
720
25%
1980
18%
720
57%
720
29%
1287
October1st to 10thNight
52%
720
24%
2065
21%
720
57%
720
33%
1251
October11th to 20thNight
41%
720
23%
2160
17%
720
50%
720
26%
1366
October21st to endNight
38%
792
24%
2376
19%
792
46%
792
23%
1581
November1st to 10thNight
45%
740
27%
2360
22%
740
54%
740
30%
1393
November11th to 20thNight
33%
760
22%
2470
14%
760
44%
760
20%
1612
November21st to endNight
35%
760
21%
2470
15%
760
44%
760
19%
1670
December1st to 10thNight
23%
760
13%
2470
8%
760
29%
760
12%
1862
December11th to 20thNight
26%
759
14%
2998
10%
759
33%
759
12%
2162
December21st to endNight
25%
828
9%
4489
7%
817
32%
817
7%
3429

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%8%36%6%35%5%5%7%35%
74918
Night
16%9%36%5%3445%7%37%
74871
TransparencyDay
47%7%11%20%13%2
74641
Night
47%6%11%20%14%2
74667
SeeingDay
22%12%26%22%13%5%
13867
Night
20%10%24%29%15%2
24018

By Month

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 10thDay
18%12%6%10%9%35%446%24%
1706
11th to 20thDay
21%16%5%10%6%345%45%22%
1656
21st to endDay
19%15%7%7%5%45%35%6%25%
1782
February1st to 10thDay
23%12%5%8%6%35%235%27%
1620
11th to 20thDay
22%12%5%9%5%345%45%27%
1701
21st to endDay
22%14%47%5%24446%30%
1480
March1st to 10thDay
18%8%46%5%34446%36%
1934
11th to 20thDay
21%10%47%5%45%5%45%31%
1980
21st to endDay
19%10%48%5%3445%5%31%
2178
April1st to 10thDay
15%9%35%6%4446%7%38%
1980
11th to 20thDay
17%7%36%5%34348%39%
2247
21st to endDay
20%8%26%5%35%46%6%35%
2340
May1st to 10thDay
19%7%37%6%45%6%6%7%31%
2340
11th to 20thDay
20%8%37%7%35%5%47%32%
2301
21st to endDay
11%5%26%6%46%6%7%9%39%
2531
June1st to 10thDay
13%5%25%6%35%5%7%10%41%
2340
11th to 20thDay
9%6%36%6%45%6%7%10%38%
2340
21st to endDay
11%425%6%46%6%8%10%38%
2340
July1st to 10thDay
11%5%25%7%46%6%6%9%39%
2340
11th to 20thDay
10%5%35%6%47%7%7%9%37%
2340
21st to endDay
13%5%36%5%46%6%6%9%37%
2547
August1st to 10thDay
11%5%26%7%47%7%8%11%33%
2327
11th to 20thDay
12%6%35%7%36%7%7%9%35%
2303
21st to endDay
10%6%25%5%35%6%6%8%43%
2520
September1st to 10thDay
13%5%245%35%5%6%7%45%
1990
11th to 20thDay
11%5%25%5%45%5%5%7%47%
1980
21st to endDay
18%6%35%435%446%42%
1980
October1st to 10thDay
14%6%25%42446%7%45%
1895
11th to 20thDay
15%7%35%435%346%44%
1800
21st to endDay
21%7%36%6%33346%40%
1980
November1st to 10thDay
13%6%25%423337%51%
1713
11th to 20thDay
16%10%36%445%345%39%
1710
21st to endDay
17%9%36%5%44446%37%
1710
December1st to 10thDay
25%13%5%7%6%34445%24%
1710
11th to 20thDay
20%14%6%8%424436%28%
2153
21st to endDay
19%19%5%9%7%45%5%5%6%17%
3124
January1st to 10thNight
17%14%6%10%7%35%445%25%
2459
11th to 20thNight
23%14%6%8%6%34445%25%
2393
21st to endNight
20%13%5%8%6%34445%29%
2574
February1st to 10thNight
22%12%5%7%6%34445%27%
2340
11th to 20thNight
22%11%48%7%35%345%28%
2143
21st to endNight
24%14%37%5%34345%28%
1776
March1st to 10thNight
17%9%36%6%44446%38%
2026
11th to 20thNight
20%8%5%7%5%3445%6%33%
1980
21st to endNight
19%9%47%6%34445%34%
2178
April1st to 10thNight
16%8%45%5%25%45%7%39%
1980
11th to 20thNight
14%7%36%43446%8%41%
1677
21st to endNight
17%6%46%5%445%5%6%38%
1620
May1st to 10thNight
17%7%36%6%46%46%6%35%
1620
11th to 20thNight
17%8%48%6%345%5%7%35%
1592
21st to endNight
11%5%245%35%7%7%10%42%
1744
June1st to 10thNight
9%5%25%5%35%5%6%9%45%
1620
11th to 20thNight
9%425%5%35%5%7%11%42%
1620
21st to endNight
10%435%5%35%5%7%11%44%
1620
July1st to 10thNight
9%6%26%5%246%6%9%43%
1620
11th to 20thNight
8%434436%5%6%10%47%
1620
21st to endNight
9%5%35%6%45%6%7%10%41%
1771
August1st to 10thNight
9%5%26%6%46%6%5%10%42%
1611
11th to 20thNight
9%6%35%5%35%5%7%8%43%
1598
21st to endNight
9%426%5%2446%9%48%
1818
September1st to 10thNight
12%4144245%5%7%50%
1966
11th to 20thNight
10%3145%3445%7%53%
1980
21st to endNight
15%425%5%3445%7%45%
1980
October1st to 10thNight
11%5%25%5%35%45%7%49%
2065
11th to 20thNight
15%6%25%434447%45%
2160
21st to endNight
21%6%245%34445%41%
2376
November1st to 10thNight
12%6%35%424345%51%
2360
11th to 20thNight
17%9%35%5%35%45%7%38%
2470
21st to endNight
18%10%36%5%34445%38%
2470
December1st to 10thNight
23%13%5%8%5%34445%27%
2470
11th to 20thNight
18%14%6%7%5%34446%29%
3042
21st to endNight
19%17%48%8%45%446%21%
4532

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
63%49%16%8%
1707
11th to 20thDay
66%5%10%15%4
1656
21st to endDay
61%5%10%16%7%2
1782
February1st to 10thDay
62%310%17%7%1
1620
11th to 20thDay
60%5%9%17%8%1
1711
21st to endDay
57%5%8%19%10%1
1480
March1st to 10thDay
49%5%8%26%11%1
1934
11th to 20thDay
55%5%9%17%13%2
1980
21st to endDay
53%6%10%19%10%2
2178
April1st to 10thDay
46%6%11%21%13%4
1980
11th to 20thDay
44%6%9%20%17%4
2247
21st to endDay
48%6%12%19%11%3
2340
May1st to 10thDay
50%7%12%19%11%2
2340
11th to 20thDay
52%7%12%17%10%2
2305
21st to endDay
40%10%15%22%13%1
2531
June1st to 10thDay
38%8%13%25%16%1
2340
11th to 20thDay
39%10%14%20%15%2
2340
21st to endDay
39%10%15%21%13%3
2340
July1st to 10thDay
41%10%13%20%15%2
2275
11th to 20thDay
39%11%14%20%15%2
2271
21st to endDay
41%9%14%22%13%2
2405
August1st to 10thDay
41%10%14%23%11%1
2314
11th to 20thDay
42%9%12%25%11%1
2303
21st to endDay
35%9%14%22%16%4
2520
September1st to 10thDay
37%7%11%20%19%6%
1990
11th to 20thDay
35%7%11%25%20%2
1980
21st to endDay
42%7%8%22%20%1
1980
October1st to 10thDay
37%6%13%22%21%2
1895
11th to 20thDay
42%49%25%18%1
1800
21st to endDay
47%49%22%17%1
1980
November1st to 10thDay
36%49%28%19%4
1713
11th to 20thDay
48%48%20%18%3
1710
21st to endDay
49%5%9%20%16%1
1710
December1st to 10thDay
63%49%19%41
1710
11th to 20thDay
58%410%17%11%
2150
21st to endDay
66%6%11%13%4
3124
January1st to 10thNight
62%5%8%15%9%1
2459
11th to 20thNight
63%410%15%7%1
2393
21st to endNight
58%410%19%7%2
2574
February1st to 10thNight
60%410%18%8%1
2340
11th to 20thNight
60%47%17%11%1
2144
21st to endNight
59%49%15%9%3
1776
March1st to 10thNight
49%47%22%15%2
2026
11th to 20thNight
51%6%10%19%12%1
1980
21st to endNight
52%5%9%17%14%3
2178
April1st to 10thNight
44%6%9%21%17%3
1980
11th to 20thNight
40%6%12%19%16%7%
1677
21st to endNight
46%6%10%20%16%2
1620
May1st to 10thNight
48%7%12%16%13%3
1620
11th to 20thNight
49%8%10%18%12%3
1593
21st to endNight
34%11%15%25%14%1
1745
June1st to 10thNight
34%8%13%25%17%3
1620
11th to 20thNight
34%10%16%17%20%3
1620
21st to endNight
34%9%15%23%18%2
1620
July1st to 10thNight
35%11%13%22%16%3
1575
11th to 20thNight
32%9%15%23%18%3
1566
21st to endNight
35%10%14%25%15%2
1672
August1st to 10thNight
37%10%13%25%14%2
1600
11th to 20thNight
36%9%12%24%17%1
1598
21st to endNight
32%7%13%24%20%4
1818
September1st to 10thNight
32%8%13%21%18%7%
1966
11th to 20thNight
31%7%12%24%24%3
1980
21st to endNight
38%7%11%20%23%1
1980
October1st to 10thNight
34%6%11%25%21%3
2065
11th to 20thNight
40%5%10%22%20%3
2160
21st to endNight
45%47%24%16%3
2376
November1st to 10thNight
36%49%22%23%5%
2360
11th to 20thNight
46%5%9%18%19%4
2470
21st to endNight
49%5%8%23%14%1
2470
December1st to 10thNight
60%5%8%19%6%1
2470
11th to 20thNight
57%5%10%20%8%1
3044
21st to endNight
64%5%9%15%6%
4532

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
29%20%34%12%41
270
11th to 20thDay
35%21%34%8%2
252
21st to endDay
34%25%27%11%3
264
February1st to 10thDay
37%22%28%10%3
240
11th to 20thDay
46%24%25%5%
240
21st to endDay
39%24%29%8%
198
March1st to 10thDay
29%21%29%17%4
374
11th to 20thDay
27%20%34%12%6%1
420
21st to endDay
31%16%34%15%5%
462
April1st to 10thDay
24%21%26%18%10%
420
11th to 20thDay
24%16%29%20%8%3
412
21st to endDay
30%13%32%16%7%3
420
May1st to 10thDay
27%16%28%19%7%4
423
11th to 20thDay
22%10%29%21%14%4
447
21st to endDay
13%7%23%29%19%9%
485
June1st to 10thDay
13%7%23%30%19%7%
450
11th to 20thDay
13%7%26%27%18%9%
450
21st to endDay
11%7%29%25%21%6%
450
July1st to 10thDay
16%317%23%21%20%
445
11th to 20thDay
10%320%36%22%9%
444
21st to endDay
16%5%18%26%25%11%
488
August1st to 10thDay
12%320%30%22%11%
446
11th to 20thDay
16%5%14%30%23%11%
439
21st to endDay
11%319%31%24%12%
495
September1st to 10thDay
14%417%26%26%12%
450
11th to 20thDay
12%315%28%29%13%
450
21st to endDay
22%8%21%27%16%6%
450
October1st to 10thDay
16%7%26%27%18%6%
450
11th to 20thDay
18%14%29%26%12%2
450
21st to endDay
27%14%27%22%9%1
495
November1st to 10thDay
18%15%33%23%8%3
311
11th to 20thDay
28%17%29%19%7%1
270
21st to endDay
23%19%34%21%3
270
December1st to 10thDay
31%20%28%16%41
270
11th to 20thDay
28%21%30%16%41
270
21st to endDay
34%18%29%13%5%
297
January1st to 10thNight
27%18%30%21%4
760
11th to 20thNight
33%14%29%21%3
737
21st to endNight
28%16%30%22%3
792
February1st to 10thNight
29%13%30%26%2
720
11th to 20thNight
32%18%30%19%1
703
21st to endNight
32%15%32%19%2
592
March1st to 10thNight
26%15%30%25%4
720
11th to 20thNight
26%15%29%21%8%
720
21st to endNight
24%16%28%25%7%
792
April1st to 10thNight
22%15%30%24%8%
720
11th to 20thNight
18%12%31%28%11%1
600
21st to endNight
19%8%35%30%7%1
540
May1st to 10thNight
18%8%31%31%11%1
540
11th to 20thNight
20%7%25%31%15%1
531
21st to endNight
13%322%31%28%4
584
June1st to 10thNight
11%321%38%24%3
540
11th to 20thNight
11%221%36%26%4
540
21st to endNight
10%319%39%26%3
540
July1st to 10thNight
11%313%35%31%7%
525
11th to 20thNight
9%117%34%35%4
522
21st to endNight
11%213%35%32%7%
591
August1st to 10thNight
10%211%37%36%3
537
11th to 20thNight
12%210%35%33%7%
534
21st to endNight
11%114%34%33%7%
630
September1st to 10thNight
14%213%32%34%5%
720
11th to 20thNight
12%116%33%33%5%
720
21st to endNight
17%421%32%23%4
720
October1st to 10thNight
12%5%23%30%27%3
720
11th to 20thNight
18%9%27%30%15%1
720
21st to endNight
23%11%23%30%12%1
792
November1st to 10thNight
15%10%26%33%16%1
740
11th to 20thNight
22%15%25%28%11%1
760
21st to endNight
24%11%23%33%8%1
760
December1st to 10thNight
30%13%28%23%6%
760
11th to 20thNight
26%14%28%27%6%
760
21st to endNight
30%15%24%29%2
836
Page generated at 2024-01-11 22:33:51. Version ac07

Copyright 2024 Attilla Danko


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