Lozano Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lozano Observatory clear sky chart from 2005-11-06 to 2024-01-13.

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
47%
23692
24%
74331
17%
23637
55%
23637
31%
43748

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
41%
946
28%
2458
12%
946
50%
946
35%
1514
January11th to 20thNight
36%
915
25%
2379
10%
915
44%
915
30%
1523
January21st to endNight
37%
834
29%
2418
14%
834
48%
834
28%
1511
February1st to 10thNight
31%
720
26%
2160
11%
720
44%
720
26%
1326
February11th to 20thNight
29%
704
22%
2098
10%
700
39%
700
26%
1289
February21st to endNight
23%
592
26%
1776
8%
592
37%
592
23%
1110
March1st to 10thNight
28%
577
24%
2017
11%
577
43%
577
21%
1246
March11th to 20thNight
30%
540
21%
1980
13%
540
39%
540
21%
1207
March21st to endNight
26%
594
24%
2178
12%
594
42%
594
25%
1247
April1st to 10thNight
26%
540
24%
1980
12%
540
43%
540
25%
1142
April11th to 20thNight
27%
533
21%
1937
13%
533
40%
533
22%
1167
April21st to endNight
28%
540
27%
1692
14%
540
45%
540
25%
1083
May1st to 10thNight
30%
540
24%
1620
15%
540
42%
540
28%
1017
May11th to 20thNight
40%
531
22%
1594
17%
531
48%
531
29%
986
May21st to endNight
41%
583
21%
1745
15%
582
52%
582
29%
1080
June1st to 10thNight
61%
540
23%
1620
21%
540
68%
540
44%
861
June11th to 20thNight
56%
540
23%
1620
19%
540
66%
540
44%
864
June21st to endNight
60%
540
22%
1620
22%
540
65%
540
34%
947
July1st to 10thNight
67%
525
16%
1575
16%
525
71%
525
33%
960
July11th to 20thNight
77%
522
26%
1566
27%
522
83%
522
46%
817
July21st to endNight
77%
591
24%
1673
24%
558
82%
558
45%
881
August1st to 10thNight
83%
537
28%
1655
30%
534
86%
534
55%
775
August11th to 20thNight
77%
534
24%
1778
26%
534
81%
534
37%
973
August21st to endNight
77%
594
18%
2065
22%
594
78%
594
33%
1152
September1st to 10thNight
70%
540
18%
1980
21%
540
72%
540
29%
1140
September11th to 20thNight
66%
540
21%
1980
22%
540
69%
540
26%
1190
September21st to endNight
67%
540
25%
1980
26%
540
68%
540
32%
1066
October1st to 10thNight
72%
540
33%
1980
34%
540
74%
540
38%
989
October11th to 20thNight
57%
616
32%
2056
25%
616
63%
616
34%
1155
October21st to endNight
51%
792
33%
2376
21%
792
58%
792
38%
1315
November1st to 10thNight
54%
740
29%
2220
21%
740
58%
740
34%
1316
November11th to 20thNight
51%
883
26%
2403
15%
883
57%
883
36%
1452
November21st to endNight
40%
950
26%
2470
12%
950
47%
950
30%
1606
December1st to 10thNight
43%
950
29%
2470
15%
950
49%
950
33%
1558
December11th to 20thNight
36%
950
25%
2900
13%
949
42%
949
24%
1893
December21st to endNight
39%
1039
17%
4312
13%
1026
46%
1026
22%
2390

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
14%6%25%5%3445%7%45%
74875
Night
15%5%2442345%7%50%
74894
TransparencyDay
38%6%10%19%18%9%
74600
Night
34%5%11%20%18%11%
74689
SeeingDay
14%8%22%30%22%4
13640
Night
17%7%24%35%16%1
23703

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
16%6%24333237%50%
1707
11th to 20thDay
20%7%33413335%47%
1643
21st to endDay
17%5%24323446%50%
1953
February1st to 10thDay
21%7%25%323345%46%
1800
11th to 20thDay
21%7%25%424446%43%
1749
21st to endDay
20%6%23323346%47%
1480
March1st to 10thDay
21%8%25%5%24345%41%
1941
11th to 20thDay
17%6%345%23446%46%
1980
21st to endDay
19%6%24323346%46%
2178
April1st to 10thDay
16%6%36%5%35%446%44%
1980
11th to 20thDay
22%5%24424445%43%
1966
21st to endDay
17%6%45%5%33435%45%
2266
May1st to 10thDay
17%6%35%5%35%5%5%6%39%
2340
11th to 20thDay
15%7%46%6%35%45%7%38%
2302
21st to endDay
16%6%46%5%46%5%6%8%34%
2531
June1st to 10thDay
6%4246%46%6%7%9%46%
2340
11th to 20thDay
7%5%25%5%35%5%6%10%44%
2340
21st to endDay
8%6%36%7%5%7%6%6%9%36%
2340
July1st to 10thDay
13%6%35%7%46%5%6%9%37%
2340
11th to 20thDay
5%3245%46%5%6%11%48%
2340
21st to endDay
6%3245%35%6%8%11%47%
2546
August1st to 10thDay
32134345%6%10%59%
2269
11th to 20thDay
6%315%6%35%5%8%10%49%
2123
21st to endDay
7%5%25%6%5%6%6%7%11%42%
2289
September1st to 10thDay
9%6%26%6%47%5%5%7%40%
1980
11th to 20thDay
12%5%36%6%45%6%7%7%39%
1980
21st to endDay
9%5%25%5%35%5%5%8%48%
1980
October1st to 10thDay
8%4245%25%5%5%8%52%
1980
11th to 20thDay
14%5%25%5%34446%49%
1886
21st to endDay
12%424324345%57%
1980
November1st to 10thDay
16%8%36%424347%43%
1858
11th to 20thDay
14%6%345%34446%48%
1772
21st to endDay
19%7%35%43443445%
1710
December1st to 10thDay
17%7%3432435%7%45%
1710
11th to 20thDay
19%7%34423445%43%
2161
21st to endDay
17%6%2432334453%
3135
January1st to 10thNight
18%413333436%52%
2458
11th to 20thNight
18%6%24323335%49%
2379
21st to endNight
20%5%23423345%48%
2418
February1st to 10thNight
20%6%23424346%48%
2160
11th to 20thNight
21%7%14322236%48%
2098
21st to endNight
23%5%24423346%45%
1776
March1st to 10thNight
20%7%24423445%44%
2017
11th to 20thNight
19%6%35%323346%44%
1980
21st to endNight
19%6%2332335%6%48%
2178
April1st to 10thNight
15%6%2442335%8%46%
1980
11th to 20thNight
21%5%24323336%46%
1937
21st to endNight
19%5%35%424335%46%
1692
May1st to 10thNight
16%6%3443435%7%45%
1620
11th to 20thNight
16%5%25%43445%8%44%
1593
21st to endNight
15%6%245%2447%9%43%
1745
June1st to 10thNight
6%4233235%5%9%58%
1620
11th to 20thNight
6%41333446%10%57%
1620
21st to endNight
9%5%24425%6%6%9%49%
1620
July1st to 10thNight
10%6%244345%7%10%46%
1620
11th to 20thNight
33133345%5%10%60%
1620
21st to endNight
6%31332446%11%56%
1772
August1st to 10thNight
22232335%10%68%
1665
11th to 20thNight
5%3144345%7%12%50%
1778
21st to endNight
7%4244345%6%10%50%
2065
September1st to 10thNight
10%5%25%5%345%5%8%48%
1980
11th to 20thNight
11%5%346%345%6%8%45%
1980
21st to endNight
9%425%4345%6%8%51%
1980
October1st to 10thNight
7%41332445%8%58%
1980
11th to 20thNight
15%42442335%5%53%
2056
21st to endNight
15%41421223460%
2376
November1st to 10thNight
13%6%25%422345%53%
2220
11th to 20thNight
13%5%24324445%53%
2403
21st to endNight
20%6%34323346%46%
2470
December1st to 10thNight
17%6%24323346%49%
2470
11th to 20thNight
20%7%35%423335%46%
3036
21st to endNight
20%6%13212335%52%
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
38%35%16%22%16%
1708
11th to 20thDay
42%35%14%18%17%
1643
21st to endDay
36%46%14%23%16%
1953
February1st to 10thDay
44%25%13%20%16%
1800
11th to 20thDay
43%46%16%19%12%
1759
21st to endDay
39%5%7%16%18%15%
1480
March1st to 10thDay
45%49%13%17%12%
1941
11th to 20thDay
41%5%7%14%17%16%
1980
21st to endDay
40%48%17%18%13%
2178
April1st to 10thDay
43%5%8%16%17%11%
1980
11th to 20thDay
44%46%16%17%13%
1966
21st to endDay
42%5%6%19%18%11%
2266
May1st to 10thDay
44%6%8%17%17%8%
2340
11th to 20thDay
45%6%8%19%18%5%
2306
21st to endDay
46%7%11%20%15%2
2531
June1st to 10thDay
31%8%13%26%19%3
2340
11th to 20thDay
34%6%12%26%17%4
2340
21st to endDay
41%8%13%23%12%3
2340
July1st to 10thDay
42%7%14%24%11%2
2276
11th to 20thDay
30%6%19%25%18%2
2271
21st to endDay
25%9%20%32%13%1
2405
August1st to 10thDay
21%6%17%38%18%1
2255
11th to 20thDay
28%9%17%30%13%4
2123
21st to endDay
35%8%17%24%12%3
2289
September1st to 10thDay
41%8%12%17%16%7%
1980
11th to 20thDay
41%8%11%19%16%5%
1980
21st to endDay
33%7%11%20%18%11%
1980
October1st to 10thDay
29%6%11%19%25%9%
1980
11th to 20thDay
37%5%9%16%18%16%
1886
21st to endDay
30%5%5%15%24%21%
1980
November1st to 10thDay
42%48%18%16%11%
1858
11th to 20thDay
38%39%16%20%14%
1772
21st to endDay
44%45%14%19%13%
1710
December1st to 10thDay
40%48%19%19%9%
1710
11th to 20thDay
42%6%7%9%21%14%
2159
21st to endDay
36%35%17%25%14%
3135
January1st to 10thNight
34%37%16%21%19%
2458
11th to 20thNight
39%36%16%20%17%
2379
21st to endNight
40%35%14%20%19%
2418
February1st to 10thNight
39%47%13%19%18%
2160
11th to 20thNight
40%36%16%18%16%
2098
21st to endNight
41%46%16%17%16%
1776
March1st to 10thNight
42%5%9%16%17%11%
2017
11th to 20thNight
42%49%13%15%17%
1980
21st to endNight
37%410%16%18%14%
2178
April1st to 10thNight
37%5%10%19%16%13%
1980
11th to 20thNight
40%49%13%16%16%
1937
21st to endNight
41%5%8%18%16%11%
1692
May1st to 10thNight
38%6%11%19%17%10%
1620
11th to 20thNight
38%6%10%24%17%5%
1594
21st to endNight
37%6%16%26%14%1
1746
June1st to 10thNight
23%6%16%30%22%3
1620
11th to 20thNight
23%6%15%31%20%5%
1620
21st to endNight
31%7%18%28%14%3
1620
July1st to 10thNight
30%10%20%29%9%2
1575
11th to 20thNight
18%10%22%30%18%1
1566
21st to endNight
19%10%26%34%10%1
1673
August1st to 10thNight
13%7%22%40%16%1
1655
11th to 20thNight
24%10%22%31%11%2
1778
21st to endNight
28%9%23%26%11%3
2065
September1st to 10thNight
33%8%17%21%15%7%
1980
11th to 20thNight
35%9%16%22%14%5%
1980
21st to endNight
30%6%15%20%17%11%
1980
October1st to 10thNight
25%6%11%27%20%11%
1980
11th to 20thNight
32%5%9%18%19%17%
2056
21st to endNight
29%46%16%24%22%
2376
November1st to 10thNight
35%38%19%20%14%
2220
11th to 20thNight
32%5%10%18%20%15%
2403
21st to endNight
40%37%16%19%13%
2470
December1st to 10thNight
37%48%20%20%12%
2470
11th to 20thNight
42%45%13%18%19%
3037
21st to endNight
35%45%13%28%14%
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
24%14%38%18%41
270
11th to 20thDay
27%15%26%26%5%2
248
21st to endDay
19%15%37%22%7%
264
February1st to 10thDay
33%14%29%16%8%
240
11th to 20thDay
30%18%33%15%41
240
21st to endDay
27%19%39%13%2
198
March1st to 10thDay
22%19%40%17%3
240
11th to 20thDay
19%18%43%16%5%
240
21st to endDay
22%16%38%18%5%
264
April1st to 10thDay
23%16%40%20%2
240
11th to 20thDay
20%20%34%21%5%
244
21st to endDay
19%11%40%25%5%
526
May1st to 10thDay
19%12%35%27%7%
603
11th to 20thDay
16%11%28%31%11%2
625
21st to endDay
16%5%28%36%13%1
679
June1st to 10thDay
7%317%44%26%3
630
11th to 20thDay
8%116%50%23%3
630
21st to endDay
11%213%37%30%7%
630
July1st to 10thDay
10%29%33%37%8%
621
11th to 20thDay
417%32%49%7%
618
21st to endDay
415%35%46%9%
684
August1st to 10thDay
37%30%48%12%
567
11th to 20thDay
7%15%37%40%11%
437
21st to endDay
6%27%26%44%16%
408
September1st to 10thDay
12%5%25%47%11%
270
11th to 20thDay
6%3430%45%13%
270
21st to endDay
11%111%26%39%12%
270
October1st to 10thDay
7%216%38%31%6%
270
11th to 20thDay
12%5%22%39%19%3
270
21st to endDay
20%13%25%25%14%3
297
November1st to 10thDay
21%9%25%29%13%4
270
11th to 20thDay
20%13%24%29%13%2
270
21st to endDay
27%17%32%16%6%1
270
December1st to 10thDay
19%10%35%25%8%3
270
11th to 20thDay
23%19%30%23%6%
270
21st to endDay
22%10%38%23%6%1
297
January1st to 10thNight
22%8%26%34%10%
950
11th to 20thNight
22%10%27%31%9%
915
21st to endNight
23%9%26%34%7%
834
February1st to 10thNight
24%11%29%29%7%
720
11th to 20thNight
27%12%29%26%5%
704
21st to endNight
27%14%33%24%2
592
March1st to 10thNight
24%11%33%29%3
577
11th to 20thNight
22%11%32%29%6%
540
21st to endNight
20%10%41%25%4
594
April1st to 10thNight
16%10%43%28%3
540
11th to 20thNight
23%10%35%28%3
533
21st to endNight
21%8%38%26%6%1
540
May1st to 10thNight
18%8%42%28%4
540
11th to 20thNight
17%6%34%34%9%
531
21st to endNight
16%7%31%35%11%
584
June1st to 10thNight
7%225%45%21%1
540
11th to 20thNight
7%131%49%11%1
540
21st to endNight
10%221%41%24%3
540
July1st to 10thNight
9%315%42%27%3
525
11th to 20thNight
3211%49%32%2
522
21st to endNight
6%29%50%31%2
591
August1st to 10thNight
219%51%34%4
537
11th to 20thNight
5%19%50%32%3
534
21st to endNight
6%26%42%40%4
594
September1st to 10thNight
11%17%41%36%4
540
11th to 20thNight
11%29%38%37%3
540
21st to endNight
10%113%34%37%4
540
October1st to 10thNight
8%214%45%28%4
540
11th to 20thNight
15%418%41%19%3
616
21st to endNight
16%9%22%33%18%3
792
November1st to 10thNight
15%6%20%35%22%2
740
11th to 20thNight
15%7%21%39%16%2
883
21st to endNight
23%9%23%31%13%1
950
December1st to 10thNight
21%7%24%35%12%1
950
11th to 20thNight
26%9%25%30%10%
950
21st to endNight
22%8%25%35%9%
1045
Page generated at 2024-01-10 18:35:21. Version ac07

Copyright 2024 Attilla Danko


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