Plettstone
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Plettstone clear sky chart from 2005-11-06 to 2024-02-15.

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
69%
23742
29%
80100
28%
23655
73%
23655
41%
41563

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
54%
750
18%
4345
19%
736
59%
736
18%
2351
January11th to 20thNight
61%
753
19%
4158
24%
740
66%
740
17%
2601
January21st to endNight
58%
829
17%
4391
27%
814
63%
814
17%
2753
February1st to 10thNight
57%
760
25%
2432
25%
760
62%
760
31%
1428
February11th to 20thNight
61%
718
31%
2151
30%
718
66%
718
38%
1190
February21st to endNight
54%
592
24%
1776
24%
592
58%
592
31%
1083
March1st to 10thNight
51%
720
18%
2160
17%
720
55%
720
28%
1371
March11th to 20thNight
54%
720
23%
1984
19%
720
58%
720
33%
1243
March21st to endNight
55%
792
20%
2051
13%
792
60%
792
39%
1250
April1st to 10thNight
56%
720
25%
1800
13%
720
61%
720
43%
1076
April11th to 20thNight
58%
711
29%
1779
14%
711
63%
711
46%
1023
April21st to endNight
63%
720
29%
1800
14%
720
68%
720
52%
980
May1st to 10thNight
65%
684
31%
1764
17%
684
69%
684
56%
907
May11th to 20thNight
67%
453
36%
1515
30%
453
73%
453
56%
644
May21st to endNight
71%
389
31%
1552
32%
388
79%
388
48%
629
June1st to 10thNight
75%
360
32%
1440
36%
360
81%
360
51%
557
June11th to 20thNight
80%
360
40%
1440
44%
360
90%
360
74%
439
June21st to endNight
85%
360
39%
1440
48%
360
90%
360
70%
462
July1st to 10thNight
93%
350
40%
1400
51%
350
95%
350
82%
407
July11th to 20thNight
92%
348
41%
1392
51%
348
93%
348
67%
459
July21st to endNight
87%
556
40%
1641
36%
525
89%
525
62%
703
August1st to 10thNight
88%
595
39%
1660
30%
592
88%
592
74%
714
August11th to 20thNight
86%
712
39%
1780
23%
712
88%
712
76%
829
August21st to endNight
93%
792
45%
1980
29%
792
93%
792
83%
877
September1st to 10thNight
90%
720
46%
1800
33%
720
91%
720
84%
801
September11th to 20thNight
86%
720
47%
1822
37%
720
89%
720
76%
834
September21st to endNight
83%
720
45%
1980
39%
720
88%
720
73%
861
October1st to 10thNight
79%
720
35%
2128
35%
720
84%
720
59%
983
October11th to 20thNight
80%
720
39%
2160
41%
720
84%
720
60%
971
October21st to endNight
77%
792
44%
2376
43%
792
83%
792
65%
1027
November1st to 10thNight
71%
740
32%
2395
35%
740
75%
740
46%
1174
November11th to 20thNight
70%
760
33%
2470
31%
760
76%
760
46%
1213
November21st to endNight
66%
760
32%
2470
31%
760
71%
760
41%
1272
December1st to 10thNight
60%
760
25%
2650
25%
760
64%
760
32%
1460
December11th to 20thNight
56%
760
21%
3220
25%
759
60%
759
20%
2094
December21st to endNight
50%
826
14%
4798
21%
817
56%
817
15%
2897

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%423323345%63%
78461
Night
11%423323345%60%
80646
TransparencyDay
24%37%19%24%22%
78175
Night
27%39%20%23%19%
80453
SeeingDay
9%9%25%34%17%5%
14205
Night
10%314%38%29%7%
23780

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
17%8%2443445%7%42%
2539
11th to 20thDay
18%6%37%7%45%45%5%34%
2764
21st to endDay
19%8%35%6%35%45%8%34%
3146
February1st to 10thDay
19%6%24313446%49%
1745
11th to 20thDay
14%5%24324448%50%
1791
21st to endDay
18%6%23434446%46%
1480
March1st to 10thDay
17%9%35%4245%6%8%37%
1800
11th to 20thDay
17%6%25%435%46%7%41%
1974
21st to endDay
14%5%2342346%6%49%
2304
April1st to 10thDay
12%5%2442335%6%54%
2160
11th to 20thDay
11%424323346%57%
2129
21st to endDay
8%423323346%63%
2160
May1st to 10thDay
5%423223346%68%
2193
11th to 20thDay
5%212323436%68%
2374
21st to endDay
6%31332345%5%64%
2723
June1st to 10thDay
3323212346%72%
2520
11th to 20thDay
111221122485%
2520
21st to endDay
211111122385%
2520
July1st to 10thDay
111212387%
2520
11th to 20thDay
111111223483%
2520
21st to endDay
111221233479%
2576
August1st to 10thDay
211111213384%
2267
11th to 20thDay
1111123387%
2122
21st to endDay
1111222388%
2376
September1st to 10thDay
11111211288%
2160
11th to 20thDay
21211222482%
2138
21st to endDay
221211123482%
1980
October1st to 10thDay
431232323474%
1828
11th to 20thDay
4212223345%72%
1800
21st to endDay
6%212322345%71%
1980
November1st to 10thDay
9%413425%446%58%
1682
11th to 20thDay
9%313333347%61%
1710
21st to endDay
12%32333345%8%55%
1710
December1st to 10thDay
15%5%23433347%52%
1528
11th to 20thDay
25%8%36%5%33345%35%
1928
21st to endDay
13%7%35%5%35%5%7%8%36%
2794
January1st to 10thNight
15%8%36%42345%6%43%
4406
11th to 20thNight
20%8%245%35%5%5%6%37%
4199
21st to endNight
21%7%35%5%3445%6%37%
4521
February1st to 10thNight
17%6%23323446%51%
2432
11th to 20thNight
13%42432335%8%54%
2151
21st to endNight
18%7%2431334451%
1776
March1st to 10thNight
18%7%24424446%45%
2160
11th to 20thNight
17%6%2433335%9%46%
1984
21st to endNight
14%6%24324346%54%
2051
April1st to 10thNight
13%42342345%7%55%
1800
11th to 20thNight
9%323433346%62%
1779
21st to endNight
6%323223346%67%
1800
May1st to 10thNight
5%312223337%69%
1764
11th to 20thNight
5%212222247%72%
1515
21st to endNight
5%212313346%70%
1552
June1st to 10thNight
3312322335%73%
1440
11th to 20thNight
11111123487%
1440
21st to endNight
111111222385%
1440
July1st to 10thNight
111121291%
1440
11th to 20thNight
211221212383%
1440
21st to endNight
2212212345%75%
1738
August1st to 10thNight
211211112384%
1669
11th to 20thNight
1222233482%
1780
21st to endNight
11111122388%
1980
September1st to 10thNight
1111112289%
1800
11th to 20thNight
21111222384%
1822
21st to endNight
211121223481%
1980
October1st to 10thNight
421221333473%
2128
11th to 20thNight
421211333475%
2160
21st to endNight
5%212212235%77%
2376
November1st to 10thNight
10%322222346%64%
2395
11th to 20thNight
9%31322346%7%61%
2470
21st to endNight
11%324323346%60%
2470
December1st to 10thNight
15%5%24323446%52%
2650
11th to 20thNight
24%8%3442335%6%38%
3276
21st to endNight
15%7%36%6%45%6%5%7%36%
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
41%416%25%12%3
2539
11th to 20thDay
51%49%16%12%8%
2764
21st to endDay
47%413%21%11%3
3146
February1st to 10thDay
38%38%26%17%9%
1745
11th to 20thDay
33%49%24%24%6%
1801
21st to endDay
40%5%8%25%20%2
1480
March1st to 10thDay
45%5%9%21%17%3
1800
11th to 20thDay
41%5%9%22%18%5%
1974
21st to endDay
35%5%15%26%15%4
2304
April1st to 10thDay
32%411%26%19%8%
2160
11th to 20thDay
29%410%28%22%7%
2132
21st to endDay
24%49%31%27%5%
2160
May1st to 10thDay
19%49%27%33%9%
2193
11th to 20thDay
19%46%26%33%12%
2377
21st to endDay
21%6%7%31%27%8%
2724
June1st to 10thDay
16%37%23%33%17%
2520
11th to 20thDay
7%2320%37%30%
2520
21st to endDay
8%118%33%49%
2520
July1st to 10thDay
5%215%24%63%
2451
11th to 20thDay
8%229%25%55%
2445
21st to endDay
9%428%25%52%
2433
August1st to 10thDay
9%219%25%54%
2251
11th to 20thDay
5%317%32%53%
2122
21st to endDay
6%18%34%49%
2376
September1st to 10thDay
7%217%27%56%
2160
11th to 20thDay
9%3120%38%28%
2138
21st to endDay
10%2217%39%30%
1980
October1st to 10thDay
16%26%17%28%31%
1828
11th to 20thDay
15%3422%27%30%
1800
21st to endDay
17%35%20%31%23%
1980
November1st to 10thDay
27%48%22%24%14%
1682
11th to 20thDay
24%310%25%27%10%
1710
21st to endDay
29%38%20%27%13%
1710
December1st to 10thDay
35%212%22%19%11%
1528
11th to 20thDay
53%36%16%14%7%
1928
21st to endDay
43%414%25%10%4
2794
January1st to 10thNight
39%5%16%25%13%3
4406
11th to 20thNight
47%414%17%11%7%
4199
21st to endNight
46%412%22%12%4
4521
February1st to 10thNight
37%39%22%19%10%
2432
11th to 20thNight
29%49%27%23%8%
2152
21st to endNight
37%410%26%19%4
1776
March1st to 10thNight
41%411%20%20%4
2160
11th to 20thNight
37%410%22%20%6%
1984
21st to endNight
33%316%25%17%5%
2051
April1st to 10thNight
30%316%24%19%7%
1800
11th to 20thNight
24%5%11%28%24%7%
1779
21st to endNight
21%411%33%27%4
1800
May1st to 10thNight
17%49%27%34%9%
1764
11th to 20thNight
15%38%30%33%11%
1515
21st to endNight
16%49%31%32%8%
1552
June1st to 10thNight
15%311%20%32%18%
1440
11th to 20thNight
5%25%20%37%31%
1440
21st to endNight
8%219%31%49%
1440
July1st to 10thNight
415%28%61%
1400
11th to 20thNight
9%218%22%58%
1392
21st to endNight
12%417%21%54%
1641
August1st to 10thNight
9%211%24%54%
1660
11th to 20thNight
8%319%30%49%
1780
21st to endNight
5%28%31%54%
1980
September1st to 10thNight
5%216%28%58%
1800
11th to 20thNight
8%3217%40%30%
1822
21st to endNight
9%2216%40%30%
1980
October1st to 10thNight
16%35%17%29%30%
2128
11th to 20thNight
14%46%19%29%29%
2160
21st to endNight
13%2425%32%25%
2376
November1st to 10thNight
23%38%25%21%19%
2395
11th to 20thNight
23%49%27%24%14%
2470
21st to endNight
27%37%22%30%11%
2470
December1st to 10thNight
33%49%23%19%13%
2650
11th to 20thNight
47%311%16%16%7%
3276
21st to endNight
45%6%14%22%9%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
31%8%20%26%13%3
180
11th to 20thDay
18%6%23%27%19%6%
313
21st to endDay
17%6%22%30%19%5%
407
February1st to 10thDay
23%11%22%24%16%5%
387
11th to 20thDay
17%9%28%31%13%3
432
21st to endDay
18%13%31%27%10%1
346
March1st to 10thDay
21%14%28%27%8%2
420
11th to 20thDay
21%14%27%22%14%3
420
21st to endDay
20%12%33%26%9%1
462
April1st to 10thDay
17%18%30%21%12%2
420
11th to 20thDay
15%18%29%28%6%3
412
21st to endDay
9%16%31%27%13%4
420
May1st to 10thDay
9%16%33%29%10%4
423
11th to 20thDay
8%13%31%32%12%4
448
21st to endDay
9%11%26%33%16%5%
485
June1st to 10thDay
412%28%34%15%7%
450
11th to 20thDay
311%30%36%14%7%
450
21st to endDay
38%24%38%19%8%
450
July1st to 10thDay
222%47%22%7%
446
11th to 20thDay
116%51%20%11%
444
21st to endDay
1119%46%23%10%
487
August1st to 10thDay
3424%45%17%8%
447
11th to 20thDay
1322%46%19%8%
437
21st to endDay
1219%51%18%9%
495
September1st to 10thDay
2321%46%21%7%
450
11th to 20thDay
37%29%35%21%4
450
21st to endDay
26%22%44%23%3
450
October1st to 10thDay
39%25%35%24%4
450
11th to 20thDay
6%7%24%32%26%5%
450
21st to endDay
6%7%24%34%25%4
495
November1st to 10thDay
10%6%21%28%27%8%
278
11th to 20thDay
7%6%21%36%22%7%
270
21st to endDay
10%424%31%24%6%
270
December1st to 10thDay
19%5%23%26%21%6%
183
11th to 20thDay
17%8%21%28%19%7%
180
21st to endDay
22%9%22%25%17%6%
198
January1st to 10thNight
20%316%32%21%9%
760
11th to 20thNight
15%316%38%22%7%
760
21st to endNight
19%214%35%23%7%
836
February1st to 10thNight
20%215%36%21%6%
760
11th to 20thNight
14%416%35%24%8%
722
21st to endNight
19%416%39%18%3
592
March1st to 10thNight
20%5%17%34%21%4
720
11th to 20thNight
16%6%18%30%23%7%
720
21st to endNight
16%5%20%36%21%2
792
April1st to 10thNight
14%5%20%36%24%3
720
11th to 20thNight
10%6%22%37%20%5%
711
21st to endNight
6%5%22%38%23%7%
720
May1st to 10thNight
6%6%19%42%21%6%
684
11th to 20thNight
6%319%42%28%2
453
21st to endNight
5%416%40%33%3
389
June1st to 10thNight
4413%41%35%3
360
11th to 20thNight
1216%45%34%2
360
21st to endNight
111%46%38%4
360
July1st to 10thNight
1451%40%4
350
11th to 20thNight
11247%43%5%
348
21st to endNight
115%33%50%10%
556
August1st to 10thNight
216%44%39%8%
595
11th to 20thNight
19%41%41%9%
712
21st to endNight
1339%48%8%
792
September1st to 10thNight
116%40%44%8%
720
11th to 20thNight
218%42%38%9%
720
21st to endNight
2111%37%39%10%
720
October1st to 10thNight
4110%45%31%8%
720
11th to 20thNight
5%211%40%32%11%
720
21st to endNight
6%113%33%31%16%
792
November1st to 10thNight
11%311%34%30%12%
740
11th to 20thNight
9%115%41%26%8%
760
21st to endNight
12%116%37%27%7%
760
December1st to 10thNight
17%313%39%21%7%
760
11th to 20thNight
21%214%38%21%5%
760
21st to endNight
20%418%35%19%4
836
Page generated at 2024-02-12 03:35:35. Version ac07

Copyright 2024 Attilla Danko


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