This page made possible by the sponsorship of: Michael Vander Vorst for the San Diego Astronomy Association.

Tierra del Sol
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Tierra del Sol clear sky chart from 2005-11-06 to 2024-05-13.

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
63%
25328
25%
84345
18%
25191
69%
25191
22%
53820

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
52%
754
32%
3977
16%
736
59%
736
15%
1982
January11th to 20thNight
54%
748
30%
3857
17%
740
64%
740
12%
2180
January21st to endNight
46%
830
18%
3915
14%
814
59%
814
12%
2566
February1st to 10thNight
50%
760
22%
2280
15%
760
60%
760
18%
1598
February11th to 20thNight
45%
740
22%
2218
16%
740
55%
740
19%
1570
February21st to endNight
44%
628
19%
1884
15%
628
52%
628
17%
1364
March1st to 10thNight
41%
756
23%
3689
14%
744
51%
744
10%
2440
March11th to 20thNight
52%
754
26%
3537
19%
740
60%
740
16%
1872
March21st to endNight
48%
830
14%
3620
12%
814
56%
814
13%
2412
April1st to 10thNight
48%
760
25%
1900
11%
760
56%
760
24%
1338
April11th to 20thNight
50%
751
27%
1879
12%
751
58%
751
26%
1287
April21st to endNight
53%
760
26%
1900
11%
760
61%
760
29%
1283
May1st to 10thNight
56%
601
28%
1741
15%
601
64%
601
29%
1085
May11th to 20thNight
64%
540
33%
1622
23%
540
68%
540
31%
974
May21st to endNight
58%
583
29%
1746
19%
582
63%
582
29%
1057
June1st to 10thNight
70%
540
26%
1620
19%
540
73%
540
28%
1017
June11th to 20thNight
71%
540
31%
1620
21%
540
76%
540
33%
946
June21st to endNight
78%
540
28%
1620
22%
540
82%
540
34%
960
July1st to 10thNight
87%
525
24%
1575
19%
525
88%
525
32%
959
July11th to 20thNight
88%
522
28%
1566
22%
522
89%
522
31%
956
July21st to endNight
84%
647
23%
1727
18%
611
85%
611
27%
1135
August1st to 10thNight
87%
716
25%
1780
16%
712
88%
712
37%
1134
August11th to 20thNight
91%
712
30%
1780
20%
712
91%
712
36%
1146
August21st to endNight
92%
792
29%
1980
21%
792
92%
792
34%
1300
September1st to 10thNight
87%
720
26%
1858
21%
720
88%
720
32%
1225
September11th to 20thNight
82%
720
33%
1980
27%
720
87%
720
36%
1215
September21st to endNight
78%
720
30%
1980
26%
720
81%
720
34%
1215
October1st to 10thNight
67%
720
24%
1980
18%
720
73%
720
25%
1334
October11th to 20thNight
73%
720
33%
1980
27%
720
79%
720
30%
1259
October21st to endNight
69%
792
26%
2419
21%
792
76%
792
27%
1524
November1st to 10thNight
67%
740
21%
2405
19%
740
72%
740
20%
1627
November11th to 20thNight
64%
760
27%
2470
23%
760
73%
760
24%
1570
November21st to endNight
54%
760
22%
2470
18%
760
61%
760
18%
1691
December1st to 10thNight
52%
760
22%
2470
18%
760
59%
760
19%
1684
December11th to 20thNight
48%
759
21%
2931
16%
758
55%
758
13%
2111
December21st to endNight
47%
828
13%
4369
17%
817
53%
817
10%
2804

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
231433335%6%66%
84087
Night
2425%33435%6%63%
85568
TransparencyDay
14%32%211%19%22%
83818
Night
16%32%210%18%22%
85359
SeeingDay
7%13%30%31%15%5%
14980
Night
5%8%19%32%28%7%
25382

By Month

Percentage Cloud Cover SW (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
45%1443435%6%62%
2858
11th to 20thDay
45%25%44446%7%57%
2965
21st to endDay
6%5%26%45%5%36%8%49%
3498
February1st to 10thDay
46%26%433345%59%
1900
11th to 20thDay
35%26%44446%7%56%
1850
21st to endDay
37%27%6%5%435%6%52%
1570
March1st to 10thDay
2325%45%5%5%9%9%49%
3138
11th to 20thDay
3425%44445%7%58%
3397
21st to endDay
35%26%5%4435%7%56%
3902
April1st to 10thDay
332443436%6%62%
2280
11th to 20thDay
2213333346%71%
2249
21st to endDay
1313323346%71%
2280
May1st to 10thDay
1324232346%70%
2437
11th to 20thDay
1112222235%78%
2329
21st to endDay
111422223479%
2530
June1st to 10thDay
1212222245%79%
2340
11th to 20thDay
111212487%
2340
21st to endDay
12112222383%
2340
July1st to 10thDay
121322224476%
2340
11th to 20thDay
121333446%8%67%
2340
21st to endDay
2214345%46%9%58%
2484
August1st to 10thDay
121223346%76%
2149
11th to 20thDay
2112333248%72%
2122
21st to endDay
211322335%5%73%
2376
September1st to 10thDay
3213232346%70%
2102
11th to 20thDay
11111212386%
1980
21st to endDay
221222223478%
1980
October1st to 10thDay
2214333246%70%
1980
11th to 20thDay
111223223478%
1980
21st to endDay
1213222235%78%
1932
November1st to 10thDay
2314433246%68%
1674
11th to 20thDay
221433435%6%69%
1710
21st to endDay
3424444446%60%
1710
December1st to 10thDay
5%5%35%44445%7%56%
1710
11th to 20thDay
46%37%7%5%5%46%8%47%
2169
21st to endDay
4427%6%7%7%5%7%7%45%
3146
January1st to 10thNight
2435%343345%64%
4097
11th to 20thNight
2435%445%46%8%54%
4003
21st to endNight
8%7%36%445%36%6%48%
4180
February1st to 10thNight
26%37%44345%6%57%
2280
11th to 20thNight
36%27%6%45%44455%
2218
21st to endNight
26%38%5%6%6%45%5%50%
1884
March1st to 10thNight
27%6%9%6%5%6%5%7%7%40%
3736
11th to 20thNight
2326%44445%6%59%
3583
21st to endNight
26%49%5%5%6%5%5%7%45%
3747
April1st to 10thNight
3425%44446%6%58%
1900
11th to 20thNight
2315%33435%6%66%
1879
21st to endNight
216%333446%67%
1900
May1st to 10thNight
115%44345%6%67%
1741
11th to 20thNight
11334345%8%69%
1621
21st to endNight
115%32325%6%70%
1746
June1st to 10thNight
1212122346%77%
1620
11th to 20thNight
11222235%83%
1620
21st to endNight
12211223383%
1620
July1st to 10thNight
11212224382%
1620
11th to 20thNight
1212213246%76%
1620
21st to endNight
132344335%7%66%
1829
August1st to 10thNight
1111122346%78%
1790
11th to 20thNight
111221213482%
1780
21st to endNight
221112223481%
1980
September1st to 10thNight
121222223479%
1858
11th to 20thNight
111212112385%
1980
21st to endNight
111222223381%
1980
October1st to 10thNight
2214433335%69%
1980
11th to 20thNight
1113323236%75%
1980
21st to endNight
1213233345%72%
2419
November1st to 10thNight
231433324471%
2405
11th to 20thNight
2315%33334469%
2470
21st to endNight
36%36%335%45%5%57%
2470
December1st to 10thNight
46%37%33445%7%54%
2470
11th to 20thNight
48%37%5%5%5%5%5%8%45%
3041
21st to endNight
45%310%5%5%5%45%7%47%
4521

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
17%24%210%28%19%
2859
11th to 20thDay
21%24%419%21%11%
2965
21st to endDay
28%21%5%14%22%11%
3498
February1st to 10thDay
21%33%18%15%22%
1900
11th to 20thDay
18%34%213%17%15%
1860
21st to endDay
23%34%210%16%15%
1570
March1st to 10thDay
22%22%116%24%15%
3138
11th to 20thDay
19%24%320%24%10%
3397
21st to endDay
27%20%320%23%7%
3902
April1st to 10thDay
14%33%112%24%16%
2280
11th to 20thDay
10%33%111%22%22%
2252
21st to endDay
10%33%10%25%22%
2280
May1st to 10thDay
6%33%111%20%29%
2437
11th to 20thDay
5%35%17%22%30%
2332
21st to endDay
435%19%26%26%
2530
June1st to 10thDay
7%35%110%20%27%
2340
11th to 20thDay
334%16%13%43%
2340
21st to endDay
6%34%312%45%
2340
July1st to 10thDay
7%35%25%11%40%
2276
11th to 20thDay
9%37%316%19%16%
2271
21st to endDay
14%38%8%14%12%14%
2346
August1st to 10thDay
7%34%411%16%28%
2135
11th to 20thDay
12%34%310%20%21%
2122
21st to endDay
11%35%38%22%21%
2376
September1st to 10thDay
12%35%35%16%28%
2102
11th to 20thDay
434%5%18%39%
1980
21st to endDay
7%35%15%15%36%
1980
October1st to 10thDay
11%36%211%17%23%
1980
11th to 20thDay
7%35%16%17%34%
1980
21st to endDay
6%37%16%15%35%
1932
November1st to 10thDay
14%40%18%16%20%
1674
11th to 20thDay
9%38%27%17%27%
1710
21st to endDay
14%39%27%18%21%
1710
December1st to 10thDay
15%39%28%15%21%
1710
11th to 20thDay
26%32%316%12%10%
2168
21st to endDay
28%25%415%19%9%
3146
January1st to 10thNight
16%24%112%25%22%
4097
11th to 20thNight
22%25%319%21%11%
4003
21st to endNight
29%24%311%23%12%
4180
February1st to 10thNight
22%34%17%11%25%
2280
11th to 20thNight
22%34%28%15%19%
2219
21st to endNight
25%34%29%14%17%
1884
March1st to 10thNight
32%25%19%20%14%
3736
11th to 20thNight
19%24%219%25%11%
3583
21st to endNight
31%23%214%20%10%
3747
April1st to 10thNight
17%34%29%21%18%
1900
11th to 20thNight
15%33%18%20%24%
1879
21st to endNight
12%34%17%21%25%
1900
May1st to 10thNight
8%34%26%19%31%
1741
11th to 20thNight
6%34%17%22%31%
1622
21st to endNight
6%35%16%23%30%
1746
June1st to 10thNight
10%34%18%19%29%
1620
11th to 20thNight
334%5%12%45%
1620
21st to endNight
5%34%211%48%
1620
July1st to 10thNight
6%35%15%11%42%
1575
11th to 20thNight
6%36%215%21%19%
1566
21st to endNight
11%37%5%15%17%16%
1727
August1st to 10thNight
6%34%311%17%29%
1780
11th to 20thNight
7%34%213%21%23%
1780
21st to endNight
7%36%18%21%27%
1980
September1st to 10thNight
9%35%26%16%32%
1858
11th to 20thNight
5%35%317%41%
1980
21st to endNight
5%35%17%17%36%
1980
October1st to 10thNight
14%36%110%17%23%
1980
11th to 20thNight
7%36%15%17%34%
1980
21st to endNight
9%37%15%15%34%
2419
November1st to 10thNight
13%40%17%17%21%
2405
11th to 20thNight
9%38%17%16%28%
2470
21st to endNight
16%39%18%17%20%
2470
December1st to 10thNight
15%39%28%15%21%
2470
11th to 20thNight
27%33%311%16%11%
3041
21st to endNight
29%26%315%18%9%
4521

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
17%13%28%32%10%
270
11th to 20thDay
14%11%29%36%10%1
336
21st to endDay
14%21%32%27%5%1
506
February1st to 10thDay
14%18%37%23%7%2
460
11th to 20thDay
12%23%34%25%6%
455
21st to endDay
14%31%29%20%5%1
382
March1st to 10thDay
15%25%35%18%6%1
460
11th to 20thDay
13%18%37%20%8%3
460
21st to endDay
17%24%34%18%7%1
506
April1st to 10thDay
9%19%38%22%10%3
460
11th to 20thDay
7%23%38%23%9%2
452
21st to endDay
8%16%35%23%13%5%
460
May1st to 10thDay
6%18%36%25%11%3
463
11th to 20thDay
5%14%39%26%11%5%
457
21st to endDay
5%18%34%25%13%5%
485
June1st to 10thDay
310%33%34%14%7%
450
11th to 20thDay
19%35%28%20%6%
450
21st to endDay
2431%32%23%8%
450
July1st to 10thDay
1223%44%21%9%
446
11th to 20thDay
2118%40%28%12%
444
21st to endDay
1111%43%30%14%
487
August1st to 10thDay
1125%38%22%12%
447
11th to 20thDay
3116%40%26%15%
437
21st to endDay
2115%43%26%14%
495
September1st to 10thDay
5%224%39%20%9%
450
11th to 20thDay
25%33%37%18%5%
450
21st to endDay
312%24%36%19%7%
450
October1st to 10thDay
411%31%36%16%2
450
11th to 20thDay
211%36%35%15%2
450
21st to endDay
49%30%35%19%3
365
November1st to 10thDay
10%11%29%31%17%3
270
11th to 20thDay
5%11%30%35%16%3
270
21st to endDay
10%21%26%28%12%3
270
December1st to 10thDay
9%14%32%30%14%1
270
11th to 20thDay
7%11%36%33%11%1
270
21st to endDay
18%18%30%23%9%2
297
January1st to 10thNight
11%9%22%34%18%6%
760
11th to 20thNight
7%11%21%38%19%4
760
21st to endNight
11%15%23%34%15%2
836
February1st to 10thNight
8%13%23%31%20%5%
760
11th to 20thNight
8%14%28%29%17%4
744
21st to endNight
11%16%25%30%14%3
628
March1st to 10thNight
11%18%25%30%14%2
760
11th to 20thNight
9%10%25%32%18%6%
760
21st to endNight
9%14%24%31%18%3
836
April1st to 10thNight
7%14%27%30%18%4
760
11th to 20thNight
6%14%27%31%18%4
751
21st to endNight
5%13%26%27%22%7%
760
May1st to 10thNight
413%24%37%19%3
601
11th to 20thNight
210%22%34%27%6%
540
21st to endNight
310%26%34%22%5%
584
June1st to 10thNight
16%22%38%27%6%
540
11th to 20thNight
15%22%39%29%5%
540
21st to endNight
2116%36%37%7%
540
July1st to 10thNight
18%32%50%9%
525
11th to 20thNight
216%32%51%8%
522
21st to endNight
21425%55%13%
647
August1st to 10thNight
17%30%46%15%
716
11th to 20thNight
21322%53%20%
712
21st to endNight
21222%52%21%
792
September1st to 10thNight
215%29%48%14%
720
11th to 20thNight
2212%33%41%11%
720
21st to endNight
15%14%32%39%10%
720
October1st to 10thNight
48%17%38%28%5%
720
11th to 20thNight
27%15%38%30%8%
720
21st to endNight
25%19%33%28%12%
792
November1st to 10thNight
6%7%17%40%22%9%
740
11th to 20thNight
35%21%38%24%9%
760
21st to endNight
8%11%22%34%20%6%
760
December1st to 10thNight
9%11%22%33%20%4
760
11th to 20thNight
11%10%24%34%18%3
760
21st to endNight
10%13%25%33%15%5%
836
Page generated at 2024-05-10 09:39:07. Version ac07

Copyright © 2024 Attilla Danko.


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