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Sky Retreat at Westwater
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Sky Retreat at Westwater clear sky chart from 2005-11-06 to 2024-01-16.

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
66%
24405
25%
74639
22%
24366
70%
24366
40%
40794

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
67%
756
18%
2457
18%
756
69%
756
29%
1487
January11th to 20thNight
66%
740
22%
2405
22%
740
69%
740
33%
1387
January21st to endNight
62%
792
21%
2574
23%
792
65%
792
29%
1571
February1st to 10thNight
63%
720
18%
2340
18%
720
68%
720
32%
1365
February11th to 20thNight
57%
700
17%
2273
16%
700
62%
700
29%
1366
February21st to endNight
55%
592
26%
1750
21%
592
62%
592
34%
1059
March1st to 10thNight
59%
720
25%
1980
20%
720
63%
720
39%
1161
March11th to 20thNight
63%
720
27%
1980
21%
720
67%
720
42%
1115
March21st to endNight
55%
792
22%
2178
15%
792
60%
792
34%
1363
April1st to 10thNight
52%
594
24%
1854
18%
594
59%
594
34%
1048
April11th to 20thNight
54%
533
26%
1777
21%
533
62%
533
35%
951
April21st to endNight
51%
540
26%
1706
20%
540
60%
540
38%
929
May1st to 10thNight
58%
540
25%
1620
19%
540
63%
540
36%
927
May11th to 20thNight
68%
531
25%
1595
22%
531
71%
531
42%
853
May21st to endNight
62%
582
26%
1614
20%
582
66%
582
45%
875
June1st to 10thNight
69%
540
30%
1440
24%
540
73%
540
56%
740
June11th to 20thNight
64%
540
31%
1440
24%
540
69%
540
55%
736
June21st to endNight
77%
540
30%
1440
27%
540
79%
540
62%
699
July1st to 10thNight
78%
525
24%
1492
22%
525
78%
525
52%
763
July11th to 20thNight
83%
522
23%
1566
20%
522
84%
522
47%
795
July21st to endNight
81%
591
23%
1674
21%
558
81%
558
41%
923
August1st to 10thNight
79%
537
24%
1602
21%
534
80%
534
42%
863
August11th to 20thNight
80%
534
32%
1602
30%
534
81%
534
50%
795
August21st to endNight
83%
594
32%
1952
35%
594
84%
594
46%
969
September1st to 10thNight
78%
540
36%
1800
39%
540
82%
540
52%
813
September11th to 20thNight
79%
656
34%
1916
32%
656
82%
656
52%
951
September21st to endNight
73%
720
37%
1998
28%
720
78%
720
57%
987
October1st to 10thNight
68%
720
30%
2160
22%
720
73%
720
47%
1096
October11th to 20thNight
75%
720
37%
2160
29%
720
80%
720
59%
993
October21st to endNight
68%
792
37%
2376
29%
792
74%
792
50%
1196
November1st to 10thNight
70%
740
36%
2220
28%
740
76%
740
54%
1049
November11th to 20thNight
69%
869
34%
2544
27%
869
74%
869
53%
1251
November21st to endNight
64%
950
26%
2660
21%
950
68%
950
43%
1490
December1st to 10thNight
65%
950
19%
2660
16%
950
67%
950
37%
1582
December11th to 20thNight
60%
948
17%
3160
13%
948
62%
948
26%
1977
December21st to endNight
54%
1025
8%
4674
11%
1022
56%
1022
18%
2669

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
34244345%6%9%57%
74672
Night
45%244345%6%8%55%
75150
TransparencyDay
22%6%13%22%22%15%
74397
Night
25%7%13%22%20%12%
74946
SeeingDay
5%7%21%34%26%7%
14120
Night
6%318%43%27%3
24433

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%36%6%37%7%9%13%38%
1708
11th to 20thDay
35%25%6%446%7%13%45%
1665
21st to endDay
5%6%25%5%45%5%6%10%45%
1782
February1st to 10thDay
25%35%5%35%6%8%12%46%
1620
11th to 20thDay
47%36%5%25%6%6%11%44%
1575
21st to endDay
5%6%36%6%346%6%8%47%
1501
March1st to 10thDay
46%25%5%35%46%10%49%
1980
11th to 20thDay
3426%425%5%7%11%51%
1980
21st to endDay
45%245%36%6%6%8%51%
2178
April1st to 10thDay
5%5%2443345%8%56%
2106
11th to 20thDay
34245%35%5%6%9%54%
2131
21st to endDay
2415%4345%6%9%58%
2250
May1st to 10thDay
34245%36%7%7%9%51%
2340
11th to 20thDay
33244335%6%9%58%
2301
21st to endDay
23244345%7%9%58%
2658
June1st to 10thDay
221232346%8%68%
2520
11th to 20thDay
2212223346%73%
2520
21st to endDay
121331235%7%73%
2520
July1st to 10thDay
21133345%6%9%63%
2417
11th to 20thDay
2313335%6%8%10%56%
2340
21st to endDay
33245%35%6%8%12%50%
2545
August1st to 10thDay
2224435%7%8%9%54%
2328
11th to 20thDay
221342346%9%64%
2299
21st to endDay
321343446%9%62%
2404
September1st to 10thDay
4213223346%69%
2160
11th to 20thDay
231332345%6%69%
2039
21st to endDay
3223313335%73%
1962
October1st to 10thDay
6%31332445%6%65%
1800
11th to 20thDay
321231235%7%73%
1800
21st to endDay
341332335%5%66%
1980
November1st to 10thDay
331322235%7%67%
1859
11th to 20thDay
35%23423346%66%
1612
21st to endDay
442442446%7%59%
1520
December1st to 10thDay
47%36%5%3445%10%50%
1520
11th to 20thDay
5%6%36%7%36%6%7%11%40%
1926
21st to endDay
5%8%35%5%35%5%6%10%44%
2826
January1st to 10thNight
46%25%436%6%8%9%45%
2457
11th to 20thNight
45%345%35%6%6%10%48%
2405
21st to endNight
5%7%36%6%46%5%7%9%43%
2574
February1st to 10thNight
36%345%35%7%7%11%48%
2340
11th to 20thNight
5%7%36%6%35%5%6%7%47%
2272
21st to endNight
5%8%36%5%3446%9%47%
1750
March1st to 10thNight
5%5%25%5%35%5%5%8%52%
1980
11th to 20thNight
5%5%25%5%3345%7%56%
1980
21st to endNight
6%6%36%5%35%5%6%8%46%
2178
April1st to 10thNight
5%5%36%5%35%5%6%6%52%
1854
11th to 20thNight
5%5%35%436%5%5%7%52%
1777
21st to endNight
6%5%25%5%3446%8%51%
1706
May1st to 10thNight
7%4245%345%6%8%50%
1620
11th to 20thNight
34245%446%7%7%55%
1594
21st to endNight
5%2235%35%46%8%57%
1614
June1st to 10thNight
331332345%8%63%
1440
11th to 20thNight
431332345%6%65%
1440
21st to endNight
2213423446%69%
1440
July1st to 10thNight
2214435%7%7%9%57%
1537
11th to 20thNight
2213445%7%9%13%50%
1620
21st to endNight
22245%36%7%9%13%46%
1773
August1st to 10thNight
3324435%6%8%11%52%
1611
11th to 20thNight
341433346%9%59%
1602
21st to endNight
3314335%6%6%10%57%
1952
September1st to 10thNight
421331346%9%64%
1800
11th to 20thNight
321333345%6%66%
1916
21st to endNight
4213322335%71%
1998
October1st to 10thNight
6%314323346%64%
2160
11th to 20thNight
3213313347%70%
2160
21st to endNight
5%413323345%66%
2376
November1st to 10thNight
3313323347%68%
2220
11th to 20thNight
3423324346%67%
2544
21st to endNight
5%5%23423448%59%
2660
December1st to 10thNight
5%6%25%425%446%55%
2660
11th to 20thNight
5%7%25%6%45%6%7%10%43%
3271
21st to endNight
5%9%36%5%35%6%7%7%44%
4869

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
33%14%23%25%5%1
1709
11th to 20thDay
28%12%25%27%8%1
1665
21st to endDay
32%10%22%24%10%1
1782
February1st to 10thDay
29%8%24%25%12%2
1620
11th to 20thDay
32%8%17%26%14%2
1584
21st to endDay
33%7%12%27%18%3
1501
March1st to 10thDay
29%7%14%27%21%2
1980
11th to 20thDay
24%7%16%30%16%6%
1980
21st to endDay
28%8%15%26%18%5%
2178
April1st to 10thDay
26%5%12%23%22%11%
2106
11th to 20thDay
24%6%13%24%23%10%
2134
21st to endDay
21%7%12%23%29%9%
2250
May1st to 10thDay
26%7%12%20%25%11%
2340
11th to 20thDay
21%6%11%22%28%12%
2304
21st to endDay
20%6%11%19%28%16%
2658
June1st to 10thDay
14%37%18%31%27%
2520
11th to 20thDay
13%36%10%24%44%
2520
21st to endDay
12%35%11%23%46%
2520
July1st to 10thDay
17%5%8%13%17%39%
2353
11th to 20thDay
18%5%12%19%21%24%
2271
21st to endDay
22%8%15%20%18%17%
2404
August1st to 10thDay
22%7%13%18%16%23%
2313
11th to 20thDay
17%5%9%18%21%29%
2299
21st to endDay
19%5%9%19%25%24%
2404
September1st to 10thDay
17%47%14%23%35%
2160
11th to 20thDay
15%6%10%17%24%27%
2039
21st to endDay
16%36%14%37%24%
1962
October1st to 10thDay
20%5%10%23%28%14%
1800
11th to 20thDay
12%49%26%37%14%
1800
21st to endDay
19%411%31%27%7%
1980
November1st to 10thDay
18%412%29%31%7%
1859
11th to 20thDay
20%413%36%24%3
1612
21st to endDay
25%416%32%21%3
1520
December1st to 10thDay
29%10%22%25%12%2
1520
11th to 20thDay
35%13%22%26%5%
1924
21st to endDay
34%13%16%20%17%1
2826
January1st to 10thNight
31%12%22%27%8%1
2457
11th to 20thNight
28%10%22%30%9%1
2405
21st to endNight
35%8%21%25%9%2
2574
February1st to 10thNight
28%11%22%26%11%2
2340
11th to 20thNight
33%9%14%24%17%3
2273
21st to endNight
32%8%13%27%17%3
1750
March1st to 10thNight
28%7%14%26%22%2
1980
11th to 20thNight
26%6%11%26%24%7%
1980
21st to endNight
34%7%12%23%19%4
2178
April1st to 10thNight
30%6%9%21%22%11%
1854
11th to 20thNight
27%7%10%22%22%11%
1777
21st to endNight
28%5%11%21%26%9%
1706
May1st to 10thNight
29%7%12%16%26%11%
1620
11th to 20thNight
24%6%11%21%28%10%
1595
21st to endNight
22%7%9%19%30%14%
1614
June1st to 10thNight
17%5%7%15%29%27%
1440
11th to 20thNight
17%6%9%10%17%42%
1440
21st to endNight
14%45%11%21%45%
1440
July1st to 10thNight
19%5%11%12%17%36%
1492
11th to 20thNight
19%7%11%17%21%25%
1566
21st to endNight
23%9%16%22%15%15%
1674
August1st to 10thNight
22%9%12%19%18%21%
1602
11th to 20thNight
19%5%11%18%18%29%
1602
21st to endNight
20%7%9%17%20%27%
1952
September1st to 10thNight
18%49%14%17%38%
1800
11th to 20thNight
18%6%9%17%20%30%
1916
21st to endNight
17%45%13%31%30%
1998
October1st to 10thNight
20%6%8%21%26%19%
2160
11th to 20thNight
15%48%19%36%19%
2160
21st to endNight
21%47%28%30%9%
2376
November1st to 10thNight
17%410%26%33%11%
2220
11th to 20thNight
18%5%10%35%30%3
2544
21st to endNight
25%6%11%27%26%5%
2660
December1st to 10thNight
30%7%18%26%17%2
2660
11th to 20thNight
32%12%19%27%9%
3272
21st to endNight
33%11%16%23%15%1
4869

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
9%323%37%20%8%
270
11th to 20thDay
7%423%40%22%4
255
21st to endDay
8%216%41%27%7%
264
February1st to 10thDay
6%224%47%17%4
240
11th to 20thDay
8%5%23%44%18%3
240
21st to endDay
6%9%28%39%15%3
274
March1st to 10thDay
8%9%25%35%21%2
420
11th to 20thDay
6%10%24%35%21%4
420
21st to endDay
8%12%35%32%12%1
462
April1st to 10thDay
7%14%25%34%15%5%
420
11th to 20thDay
9%17%30%30%12%2
412
21st to endDay
5%16%30%27%20%1
420
May1st to 10thDay
6%12%34%30%16%3
423
11th to 20thDay
5%10%24%33%21%7%
448
21st to endDay
5%10%22%31%26%6%
613
June1st to 10thDay
36%19%37%30%6%
630
11th to 20thDay
37%24%34%27%4
630
21st to endDay
26%20%37%31%4
630
July1st to 10thDay
1214%31%42%9%
523
11th to 20thDay
3114%32%38%12%
444
21st to endDay
317%34%41%13%
487
August1st to 10thDay
3216%36%35%9%
447
11th to 20thDay
2214%33%36%13%
437
21st to endDay
3215%34%35%10%
495
September1st to 10thDay
4219%31%32%13%
450
11th to 20thDay
3424%33%28%8%
450
21st to endDay
49%18%26%32%10%
432
October1st to 10thDay
8%7%18%28%24%14%
270
11th to 20thDay
39%17%30%31%10%
270
21st to endDay
5%7%22%33%30%4
297
November1st to 10thDay
411%24%31%24%5%
270
11th to 20thDay
2419%46%21%9%
270
21st to endDay
6%5%23%35%25%6%
270
December1st to 10thDay
46%22%43%17%7%
270
11th to 20thDay
7%321%39%26%4
270
21st to endDay
10%9%18%42%16%4
297
January1st to 10thNight
6%316%44%27%4
760
11th to 20thNight
6%417%45%25%3
740
21st to endNight
8%318%46%21%4
792
February1st to 10thNight
5%222%48%20%3
720
11th to 20thNight
7%323%47%18%2
704
21st to endNight
7%5%24%49%14%1
592
March1st to 10thNight
6%5%22%47%18%1
720
11th to 20thNight
5%420%46%23%2
720
21st to endNight
6%426%45%17%1
792
April1st to 10thNight
7%6%27%45%13%1
594
11th to 20thNight
7%7%26%43%16%1
533
21st to endNight
8%7%28%32%23%2
540
May1st to 10thNight
8%5%23%44%19%1
540
11th to 20thNight
4418%45%26%3
531
21st to endNight
6%6%20%37%28%3
584
June1st to 10thNight
4219%41%32%2
540
11th to 20thNight
3423%44%23%2
540
21st to endNight
2214%45%36%1
540
July1st to 10thNight
1111%37%46%4
525
11th to 20thNight
36%37%49%5%
522
21st to endNight
36%30%55%5%
591
August1st to 10thNight
415%39%48%3
537
11th to 20thNight
4110%40%42%3
534
21st to endNight
316%39%46%6%
594
September1st to 10thNight
410%42%38%5%
540
11th to 20thNight
3111%43%39%4
656
21st to endNight
5%314%34%36%8%
720
October1st to 10thNight
6%317%43%27%4
720
11th to 20thNight
3217%43%31%4
720
21st to endNight
6%218%41%29%4
792
November1st to 10thNight
4318%45%28%3
740
11th to 20thNight
4220%48%22%4
869
21st to endNight
6%5%19%40%26%4
950
December1st to 10thNight
7%317%50%21%2
950
11th to 20thNight
10%220%43%24%2
950
21st to endNight
10%5%19%47%17%2
1041
Page generated at 2024-01-12 23:38:13. Version ac07

Copyright 2024 Attilla Danko


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