Vale
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Vale clear sky chart from 2005-11-06 to 2024-01-12.

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
55%
22711
19%
74680
17%
22678
60%
22678
27%
46084

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
39%
756
5%
2646
4%
756
42%
756
10%
2136
January11th to 20thNight
39%
728
8%
2548
7%
728
42%
728
12%
1970
January21st to endNight
45%
792
8%
2772
7%
792
48%
792
14%
2074
February1st to 10thNight
45%
720
9%
2391
7%
720
50%
720
17%
1727
February11th to 20thNight
51%
702
15%
2099
11%
700
57%
700
23%
1440
February21st to endNight
45%
592
14%
1776
12%
592
50%
592
21%
1249
March1st to 10thNight
49%
720
14%
2160
12%
720
53%
720
23%
1464
March11th to 20thNight
52%
720
17%
2102
14%
720
56%
720
26%
1381
March21st to endNight
43%
792
14%
2013
8%
792
45%
792
24%
1453
April1st to 10thNight
48%
720
19%
1800
9%
720
52%
720
31%
1198
April11th to 20thNight
49%
707
23%
1775
10%
707
54%
707
32%
1159
April21st to endNight
53%
540
24%
1620
14%
540
60%
540
37%
924
May1st to 10thNight
54%
540
23%
1620
15%
540
61%
540
40%
887
May11th to 20thNight
59%
373
21%
1435
24%
373
63%
373
29%
769
May21st to endNight
55%
388
15%
1552
20%
388
60%
388
23%
924
June1st to 10thNight
57%
360
14%
1440
18%
360
64%
360
25%
804
June11th to 20thNight
53%
360
20%
1440
24%
360
64%
360
33%
704
June21st to endNight
65%
360
25%
1440
35%
360
75%
360
46%
599
July1st to 10thNight
68%
350
24%
1400
33%
350
78%
350
53%
534
July11th to 20thNight
70%
348
32%
1392
40%
348
83%
348
69%
448
July21st to endNight
72%
394
36%
1488
41%
372
81%
372
58%
539
August1st to 10thNight
69%
388
32%
1454
32%
386
77%
386
48%
619
August11th to 20thNight
80%
574
36%
1642
27%
574
83%
574
68%
706
August21st to endNight
77%
792
37%
1980
23%
792
79%
792
67%
982
September1st to 10thNight
78%
720
38%
1800
22%
720
81%
720
67%
887
September11th to 20thNight
76%
720
36%
1922
27%
720
80%
720
56%
993
September21st to endNight
70%
720
36%
1980
30%
720
74%
720
52%
1025
October1st to 10thNight
65%
720
27%
1998
21%
720
70%
720
43%
1116
October11th to 20thNight
65%
720
30%
2222
28%
720
71%
720
43%
1168
October21st to endNight
62%
792
23%
2574
22%
792
69%
792
32%
1483
November1st to 10thNight
57%
740
22%
2405
22%
740
60%
740
26%
1502
November11th to 20thNight
52%
760
16%
2470
14%
760
55%
760
22%
1645
November21st to endNight
52%
760
14%
2579
11%
760
57%
760
23%
1655
December1st to 10thNight
44%
760
11%
2660
8%
760
48%
760
15%
1938
December11th to 20thNight
45%
759
7%
3258
7%
759
47%
759
10%
2538
December21st to endNight
35%
824
6%
4827
6%
817
40%
817
7%
3444

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
8%6%35%5%3445%7%50%
74819
Night
9%7%36%5%3445%7%46%
74916
TransparencyDay
33%7%12%19%18%11%
74523
Night
36%8%13%19%15%8%
74733
SeeingDay
9%6%17%28%27%13%
13361
Night
11%320%39%23%3
22731

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
15%13%5%10%9%5%5%6%6%422%
1519
11th to 20thDay
16%12%5%12%8%46%45%7%20%
1451
21st to endDay
12%14%6%12%8%5%5%5%6%7%20%
1584
February1st to 10thDay
13%12%48%7%36%45%6%32%
1563
11th to 20thDay
11%8%48%8%35%5%6%7%34%
1750
21st to endDay
9%8%46%6%46%5%7%9%36%
1480
March1st to 10thDay
10%9%48%6%47%6%6%7%33%
1800
11th to 20thDay
10%9%46%6%36%5%7%7%38%
1858
21st to endDay
11%8%48%5%46%6%6%7%36%
2340
April1st to 10thDay
9%8%35%5%36%5%7%8%41%
2160
11th to 20thDay
6%7%36%6%35%6%6%7%45%
2132
21st to endDay
7%6%35%5%35%5%5%8%49%
2340
May1st to 10thDay
5%5%245%3445%8%55%
2340
11th to 20thDay
9%5%344345%6%8%48%
2454
21st to endDay
7%5%36%6%46%5%7%9%42%
2723
June1st to 10thDay
7%5%346%45%6%7%8%46%
2520
11th to 20thDay
7%32342446%8%58%
2520
21st to endDay
3313323446%70%
2520
July1st to 10thDay
221221335%5%73%
2520
11th to 20thDay
111221222481%
2520
21st to endDay
221222233478%
2741
August1st to 10thDay
3313323446%68%
2477
11th to 20thDay
2111222246%77%
2256
21st to endDay
2312222345%76%
2376
September1st to 10thDay
3212213335%75%
2160
11th to 20thDay
331333445%7%65%
2037
21st to endDay
5%314424346%64%
1980
October1st to 10thDay
8%5%25%434346%57%
1958
11th to 20thDay
7%4245%2445%8%56%
1736
21st to endDay
9%6%35%5%35%46%7%46%
1782
November1st to 10thDay
14%8%35%5%35%46%8%39%
1674
11th to 20thDay
12%8%49%6%35%5%6%5%36%
1710
21st to endDay
10%8%5%11%7%5%6%6%6%6%32%
1596
December1st to 10thDay
18%12%48%6%46%45%7%26%
1520
11th to 20thDay
17%12%7%16%9%4445%417%
1928
21st to endDay
12%14%5%10%10%6%6%5%5%5%23%
2794
January1st to 10thNight
15%13%6%10%7%36%5%5%6%23%
2646
11th to 20thNight
15%12%5%10%8%35%45%6%26%
2548
21st to endNight
11%12%5%10%7%35%45%6%31%
2772
February1st to 10thNight
11%10%48%6%35%6%6%7%33%
2391
11th to 20thNight
11%9%47%5%35%5%6%7%39%
2098
21st to endNight
11%9%47%7%45%7%6%8%33%
1776
March1st to 10thNight
10%9%36%7%45%5%5%8%37%
2160
11th to 20thNight
9%8%46%6%35%47%9%40%
2102
21st to endNight
10%8%49%7%46%6%5%8%34%
2013
April1st to 10thNight
10%7%46%6%25%5%5%6%45%
1800
11th to 20thNight
8%7%26%6%35%5%5%7%45%
1775
21st to endNight
8%6%25%3245%5%8%52%
1620
May1st to 10thNight
6%415%436%5%5%7%55%
1620
11th to 20thNight
6%426%5%345%8%10%46%
1435
21st to endNight
8%6%47%6%35%6%7%8%40%
1552
June1st to 10thNight
7%436%6%45%5%5%8%47%
1440
11th to 20thNight
6%425%43445%8%57%
1440
21st to endNight
321332445%7%66%
1440
July1st to 10thNight
121232335%7%70%
1440
11th to 20thNight
1122224482%
1440
21st to endNight
221232334474%
1576
August1st to 10thNight
231342446%6%65%
1462
11th to 20thNight
111222235%6%75%
1642
21st to endNight
2212322245%74%
1980
September1st to 10thNight
4212212245%75%
1800
11th to 20thNight
5%21333335%6%67%
1922
21st to endNight
6%312324446%64%
1980
October1st to 10thNight
8%5%24323346%59%
1998
11th to 20thNight
7%414423447%60%
2222
21st to endNight
8%5%245%45%5%5%8%49%
2574
November1st to 10thNight
13%7%36%5%35%5%5%6%44%
2405
11th to 20thNight
15%7%46%435%5%5%7%39%
2470
21st to endNight
12%8%35%6%35%45%6%43%
2579
December1st to 10thNight
15%12%49%5%34447%33%
2660
11th to 20thNight
16%12%5%10%7%45%5%5%6%24%
3276
21st to endNight
13%14%48%6%36%5%6%7%28%
4862

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%12%13%11%2
1519
11th to 20thDay
63%12%13%9%3
1451
21st to endDay
61%12%13%9%31
1584
February1st to 10thDay
51%11%19%15%41
1563
11th to 20thDay
45%12%16%19%7%
1760
21st to endDay
40%10%21%18%10%1
1480
March1st to 10thDay
46%11%15%20%6%2
1800
11th to 20thDay
43%9%15%23%11%
1858
21st to endDay
44%9%17%20%9%1
2340
April1st to 10thDay
37%9%16%22%13%2
2160
11th to 20thDay
35%8%13%25%16%4
2135
21st to endDay
32%6%14%27%18%3
2340
May1st to 10thDay
26%6%11%30%21%5%
2340
11th to 20thDay
31%7%12%26%18%5%
2457
21st to endDay
35%10%17%21%15%3
2724
June1st to 10thDay
33%8%12%24%20%2
2520
11th to 20thDay
24%6%10%25%26%10%
2520
21st to endDay
15%48%20%31%21%
2520
July1st to 10thDay
13%36%15%28%35%
2451
11th to 20thDay
9%2411%27%48%
2445
21st to endDay
11%2310%27%47%
2589
August1st to 10thDay
17%47%14%29%29%
2460
11th to 20thDay
9%36%16%35%30%
2256
21st to endDay
12%37%17%38%24%
2376
September1st to 10thDay
13%35%19%32%28%
2160
11th to 20thDay
19%5%10%23%30%14%
2037
21st to endDay
21%5%9%28%29%8%
1980
October1st to 10thDay
28%7%12%26%24%4
1958
11th to 20thDay
27%6%15%31%18%3
1736
21st to endDay
33%9%18%27%12%1
1782
November1st to 10thDay
41%8%18%22%9%
1674
11th to 20thDay
46%10%19%19%6%1
1710
21st to endDay
48%12%18%16%6%1
1596
December1st to 10thDay
55%12%17%11%5%
1520
11th to 20thDay
67%11%10%8%3
1928
21st to endDay
57%13%15%11%4
2794
January1st to 10thNight
59%13%16%8%3
2646
11th to 20thNight
58%10%14%15%3
2548
21st to endNight
53%11%19%14%3
2772
February1st to 10thNight
47%12%19%17%4
2391
11th to 20thNight
43%10%19%19%9%
2099
21st to endNight
44%11%17%19%8%1
1776
March1st to 10thNight
43%8%14%22%10%2
2160
11th to 20thNight
39%9%15%27%10%1
2102
21st to endNight
46%8%15%22%8%
2013
April1st to 10thNight
37%8%14%22%17%2
1800
11th to 20thNight
35%8%12%26%16%3
1775
21st to endNight
29%6%13%26%23%3
1620
May1st to 10thNight
25%6%12%26%27%4
1620
11th to 20thNight
30%8%14%24%19%5%
1435
21st to endNight
37%9%14%25%12%3
1552
June1st to 10thNight
33%8%15%23%20%2
1440
11th to 20thNight
25%6%10%22%27%8%
1440
21st to endNight
18%37%21%33%17%
1440
July1st to 10thNight
13%45%18%28%32%
1400
11th to 20thNight
8%25%14%27%45%
1392
21st to endNight
13%249%25%46%
1488
August1st to 10thNight
18%49%15%26%29%
1454
11th to 20thNight
10%36%13%27%40%
1642
21st to endNight
13%35%15%33%30%
1980
September1st to 10thNight
13%25%17%28%34%
1800
11th to 20thNight
18%48%20%27%23%
1922
21st to endNight
20%46%24%31%15%
1980
October1st to 10thNight
27%49%26%26%7%
1998
11th to 20thNight
24%5%12%30%24%4
2222
21st to endNight
31%8%15%25%20%1
2574
November1st to 10thNight
39%7%14%24%14%1
2405
11th to 20thNight
42%10%18%22%8%
2470
21st to endNight
40%9%19%22%9%1
2579
December1st to 10thNight
50%11%16%16%6%
2660
11th to 20thNight
57%13%16%12%3
3276
21st to endNight
50%15%18%11%5%
4862

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
20%6%16%32%21%6%
180
11th to 20thDay
21%8%13%27%21%9%
163
21st to endDay
22%215%31%23%7%
176
February1st to 10thDay
18%322%31%22%4
268
11th to 20thDay
14%5%22%35%18%6%
415
21st to endDay
10%7%30%30%18%4
346
March1st to 10thDay
15%9%24%34%16%2
420
11th to 20thDay
13%8%22%30%23%3
420
21st to endDay
13%12%23%29%19%4
462
April1st to 10thDay
12%13%23%21%22%9%
420
11th to 20thDay
10%13%26%27%14%10%
412
21st to endDay
8%9%26%29%20%8%
420
May1st to 10thDay
5%11%22%27%24%10%
423
11th to 20thDay
17%8%18%25%22%11%
448
21st to endDay
8%5%15%29%25%18%
485
June1st to 10thDay
7%6%19%26%24%18%
450
11th to 20thDay
8%8%23%30%22%10%
450
21st to endDay
3217%30%31%17%
450
July1st to 10thDay
3211%34%35%15%
446
11th to 20thDay
1210%35%37%14%
444
21st to endDay
219%29%40%19%
487
August1st to 10thDay
5%111%29%38%17%
447
11th to 20thDay
2110%25%36%27%
437
21st to endDay
3212%29%31%23%
495
September1st to 10thDay
4210%23%36%24%
450
11th to 20thDay
4312%24%35%22%
450
21st to endDay
6%313%27%33%18%
450
October1st to 10thDay
8%415%23%30%20%
450
11th to 20thDay
8%316%28%26%18%
386
21st to endDay
11%8%16%27%29%10%
297
November1st to 10thDay
14%7%16%27%30%6%
270
11th to 20thDay
11%6%17%29%28%9%
270
21st to endDay
15%413%27%34%7%
216
December1st to 10thDay
22%417%27%18%12%
180
11th to 20thDay
24%6%18%29%19%3
180
21st to endDay
18%5%18%31%23%6%
198
January1st to 10thNight
19%419%34%20%4
760
11th to 20thNight
18%419%33%22%4
728
21st to endNight
16%219%36%23%4
792
February1st to 10thNight
16%323%38%18%2
720
11th to 20thNight
14%221%41%20%2
704
21st to endNight
14%327%40%15%1
592
March1st to 10thNight
12%425%39%17%2
720
11th to 20thNight
12%5%21%41%19%1
720
21st to endNight
13%5%28%38%14%1
792
April1st to 10thNight
13%6%23%36%21%2
720
11th to 20thNight
10%6%27%36%19%2
707
21st to endNight
10%428%38%18%1
540
May1st to 10thNight
7%6%28%39%18%1
540
11th to 20thNight
9%421%37%25%5%
373
21st to endNight
9%421%39%23%4
389
June1st to 10thNight
8%5%22%38%25%3
360
11th to 20thNight
8%7%28%35%21%2
360
21st to endNight
5%324%44%24%1
360
July1st to 10thNight
3321%52%21%1
350
11th to 20thNight
1124%58%15%
348
21st to endNight
2121%51%24%2
394
August1st to 10thNight
4120%45%28%2
388
11th to 20thNight
2213%46%36%2
574
21st to endNight
3215%43%34%3
792
September1st to 10thNight
5%113%40%36%5%
720
11th to 20thNight
4212%37%39%6%
720
21st to endNight
8%215%36%31%8%
720
October1st to 10thNight
10%316%38%28%6%
720
11th to 20thNight
8%318%36%29%6%
720
21st to endNight
9%318%39%27%4
792
November1st to 10thNight
14%317%39%25%2
740
11th to 20thNight
16%318%40%20%3
760
21st to endNight
15%321%33%24%5%
760
December1st to 10thNight
20%319%37%19%3
760
11th to 20thNight
22%315%40%19%2
760
21st to endNight
22%5%22%36%13%2
836
Page generated at 2024-01-09 14:24:25. Version ac07

Copyright 2024 Attilla Danko


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