Claude
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Claude 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
51%
24318
31%
79357
19%
24222
62%
24222
41%
40065

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
46%
941
34%
4019
13%
926
59%
926
32%
1913
January11th to 20thNight
47%
946
35%
3980
17%
930
58%
930
38%
1629
January21st to endNight
46%
859
26%
4068
20%
846
62%
846
27%
2149
February1st to 10thNight
40%
760
33%
2280
15%
760
57%
760
39%
1219
February11th to 20thNight
37%
722
30%
2152
14%
718
52%
718
36%
1176
February21st to endNight
34%
592
37%
1776
13%
592
55%
592
41%
905
March1st to 10thNight
38%
720
31%
2160
13%
720
52%
720
39%
1138
March11th to 20thNight
38%
601
28%
2041
18%
601
50%
601
34%
1049
March21st to endNight
32%
594
31%
2120
14%
594
55%
594
35%
1038
April1st to 10thNight
36%
540
35%
1800
18%
540
59%
540
42%
844
April11th to 20thNight
30%
533
29%
1777
14%
533
50%
533
35%
913
April21st to endNight
41%
540
30%
1764
21%
540
58%
540
40%
872
May1st to 10thNight
41%
540
30%
1620
18%
540
60%
540
40%
871
May11th to 20thNight
45%
531
23%
1593
18%
531
56%
531
37%
900
May21st to endNight
45%
584
23%
1745
16%
582
57%
582
38%
985
June1st to 10thNight
57%
540
22%
1620
17%
540
66%
540
42%
879
June11th to 20thNight
52%
540
25%
1620
16%
540
63%
540
48%
807
June21st to endNight
66%
540
26%
1620
24%
540
70%
540
51%
792
July1st to 10thNight
71%
525
20%
1575
20%
525
73%
525
40%
873
July11th to 20thNight
77%
522
27%
1566
26%
522
80%
522
50%
796
July21st to endNight
85%
591
30%
1673
33%
558
87%
558
51%
826
August1st to 10thNight
78%
537
28%
1718
33%
534
81%
534
46%
847
August11th to 20thNight
73%
534
23%
1778
27%
534
75%
534
33%
1020
August21st to endNight
79%
594
26%
1980
29%
594
81%
594
45%
971
September1st to 10thNight
72%
540
27%
1840
28%
540
75%
540
37%
973
September11th to 20thNight
63%
540
29%
1980
30%
540
68%
540
32%
1070
September21st to endNight
64%
540
35%
1980
34%
540
70%
540
46%
879
October1st to 10thNight
57%
540
34%
1980
29%
540
66%
540
38%
972
October11th to 20thNight
52%
540
40%
1980
24%
540
70%
540
47%
859
October21st to endNight
53%
933
37%
2517
18%
933
63%
933
52%
1286
November1st to 10thNight
57%
925
35%
2405
16%
925
66%
925
59%
1210
November11th to 20thNight
51%
950
37%
2470
16%
950
62%
950
58%
1224
November21st to endNight
48%
950
36%
2470
17%
950
59%
950
46%
1362
December1st to 10thNight
46%
950
36%
2470
16%
950
58%
950
47%
1352
December11th to 20thNight
39%
948
36%
2878
15%
948
54%
948
39%
1526
December21st to endNight
39%
1036
24%
4342
15%
1026
52%
1026
33%
1940

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
7%42342445%7%60%
78840
Night
6%42332445%7%60%
80312
TransparencyDay
24%5%9%23%26%13%
78568
Night
23%5%10%21%27%14%
80107
SeeingDay
9%8%28%32%19%4
14233
Night
8%8%29%39%15%1
24351

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
7%7%24424345%56%
2847
11th to 20thDay
4313423345%68%
2850
21st to endDay
9%5%25%424347%55%
3459
February1st to 10thDay
6%5%23313446%61%
1900
11th to 20thDay
6%6%25%413345%60%
1789
21st to endDay
46%23423445%63%
1480
March1st to 10thDay
7%42342445%8%56%
1800
11th to 20thDay
11%423423345%60%
1917
21st to endDay
7%424324347%60%
2232
April1st to 10thDay
5%413323345%66%
2160
11th to 20thDay
10%424323346%59%
2131
21st to endDay
8%31331435%6%62%
2196
May1st to 10thDay
9%423323347%59%
2340
11th to 20thDay
10%32342445%6%55%
2302
21st to endDay
9%323435%46%8%53%
2531
June1st to 10thDay
6%4244345%6%9%54%
2340
11th to 20thDay
5%31322345%9%62%
2340
21st to endDay
42133235%6%8%62%
2340
July1st to 10thDay
7%424335%6%7%9%51%
2340
11th to 20thDay
42134245%6%8%62%
2340
21st to endDay
2213436%6%6%10%57%
2546
August1st to 10thDay
4323425%47%8%57%
2206
11th to 20thDay
6%314435%6%7%9%50%
2123
21st to endDay
6%324435%6%6%8%53%
2376
September1st to 10thDay
8%4133335%6%6%58%
2120
11th to 20thDay
9%4245%35%45%6%53%
1980
21st to endDay
8%313223446%63%
1980
October1st to 10thDay
11%414322336%61%
1980
11th to 20thDay
8%31221333469%
1980
21st to endDay
8%41331233469%
1816
November1st to 10thDay
5%412212347%69%
1673
11th to 20thDay
3222322445%72%
1710
21st to endDay
8%5%33222345%63%
1710
December1st to 10thDay
6%423413336%65%
1710
11th to 20thDay
8%3244245%47%59%
2161
21st to endDay
7%6%1332335%5%61%
3135
January1st to 10thNight
6%6%3432445%6%58%
4108
11th to 20thNight
332332445%7%65%
4120
21st to endNight
6%8%26%423346%54%
4238
February1st to 10thNight
7%6%23324345%61%
2280
11th to 20thNight
7%5%24423445%59%
2152
21st to endNight
6%5%1432335%7%61%
1776
March1st to 10thNight
5%5%2432445%8%58%
2160
11th to 20thNight
10%433323345%60%
2041
21st to endNight
6%42333446%7%59%
2120
April1st to 10thNight
5%312323347%66%
1800
11th to 20thNight
9%32233435%6%60%
1777
21st to endNight
9%312224448%62%
1764
May1st to 10thNight
8%32322435%8%60%
1620
11th to 20thNight
9%4143245%5%7%55%
1593
21st to endNight
9%423425%46%7%54%
1745
June1st to 10thNight
5%3133246%6%10%55%
1620
11th to 20thNight
431342345%10%61%
1620
21st to endNight
331231447%10%61%
1620
July1st to 10thNight
6%224435%5%6%12%51%
1620
11th to 20thNight
331333446%10%59%
1620
21st to endNight
22123245%7%13%59%
1772
August1st to 10thNight
32133345%7%11%56%
1728
11th to 20thNight
6%4245%46%5%7%10%48%
1778
21st to endNight
331333447%11%57%
1980
September1st to 10thNight
6%4245%245%5%7%57%
1840
11th to 20thNight
9%5%25%42445%7%53%
1980
21st to endNight
6%41222335%6%66%
1980
October1st to 10thNight
9%5%13323345%61%
1980
11th to 20thNight
9%21221123472%
1980
21st to endNight
6%312323336%69%
2517
November1st to 10thNight
6%212312336%72%
2405
11th to 20thNight
3412222246%72%
2470
21st to endNight
8%323323446%63%
2470
December1st to 10thNight
6%313314447%62%
2470
11th to 20thNight
6%5%1433445%8%58%
3036
21st to endNight
6%42342345%7%61%
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
29%5%6%21%27%11%
2848
11th to 20thDay
19%48%26%31%12%
2850
21st to endDay
29%5%7%22%29%8%
3459
February1st to 10thDay
25%29%25%26%14%
1900
11th to 20thDay
27%36%24%24%16%
1799
21st to endDay
24%35%19%31%18%
1480
March1st to 10thDay
26%47%19%28%17%
1800
11th to 20thDay
27%48%21%26%14%
1917
21st to endDay
25%37%26%23%16%
2232
April1st to 10thDay
21%47%18%27%23%
2160
11th to 20thDay
27%47%19%24%19%
2134
21st to endDay
23%49%24%28%11%
2196
May1st to 10thDay
26%5%9%18%23%19%
2340
11th to 20thDay
29%5%10%23%23%10%
2306
21st to endDay
27%7%14%20%19%12%
2531
June1st to 10thDay
26%7%15%27%15%10%
2340
11th to 20thDay
20%6%10%22%26%15%
2340
21st to endDay
19%5%14%29%21%12%
2340
July1st to 10thDay
26%10%13%26%19%5%
2276
11th to 20thDay
19%6%11%27%29%9%
2271
21st to endDay
19%9%17%30%21%3
2405
August1st to 10thDay
21%8%13%31%21%6%
2192
11th to 20thDay
27%7%16%23%20%6%
2123
21st to endDay
26%8%13%23%20%10%
2376
September1st to 10thDay
26%7%12%21%22%13%
2120
11th to 20thDay
31%7%9%21%27%6%
1980
21st to endDay
21%49%22%31%12%
1980
October1st to 10thDay
27%5%8%22%25%13%
1980
11th to 20thDay
20%46%14%31%25%
1980
21st to endDay
22%35%24%31%16%
1816
November1st to 10thDay
17%38%19%34%20%
1673
11th to 20thDay
15%47%26%33%17%
1710
21st to endDay
25%3416%33%19%
1710
December1st to 10thDay
24%48%24%29%10%
1710
11th to 20thDay
25%38%21%28%15%
2159
21st to endDay
25%37%20%31%13%
3135
January1st to 10thNight
25%5%9%25%27%9%
4108
11th to 20thNight
18%5%14%19%33%11%
4120
21st to endNight
30%5%7%18%31%9%
4238
February1st to 10thNight
27%37%19%29%15%
2280
11th to 20thNight
28%37%21%24%17%
2152
21st to endNight
23%36%19%27%22%
1776
March1st to 10thNight
24%48%19%25%19%
2160
11th to 20thNight
27%46%22%23%18%
2041
21st to endNight
24%5%10%25%23%13%
2120
April1st to 10thNight
19%5%9%20%25%22%
1800
11th to 20thNight
25%5%9%19%25%16%
1777
21st to endNight
21%6%13%22%24%14%
1764
May1st to 10thNight
24%6%9%17%23%21%
1620
11th to 20thNight
27%7%12%19%22%13%
1594
21st to endNight
27%7%15%18%18%14%
1746
June1st to 10thNight
22%8%18%28%16%8%
1620
11th to 20thNight
19%6%13%23%25%15%
1620
21st to endNight
17%6%15%25%23%13%
1620
July1st to 10thNight
24%9%17%29%16%6%
1575
11th to 20thNight
19%6%11%21%29%13%
1566
21st to endNight
16%8%14%31%26%5%
1673
August1st to 10thNight
19%7%14%29%23%8%
1718
11th to 20thNight
30%8%14%22%20%5%
1778
21st to endNight
20%7%16%27%23%7%
1980
September1st to 10thNight
27%6%10%23%22%12%
1840
11th to 20thNight
32%5%11%18%27%7%
1980
21st to endNight
19%5%8%20%31%16%
1980
October1st to 10thNight
24%5%10%19%25%16%
1980
11th to 20thNight
19%36%15%33%24%
1980
21st to endNight
19%35%20%34%18%
2517
November1st to 10thNight
17%28%21%32%20%
2405
11th to 20thNight
15%36%24%35%18%
2470
21st to endNight
23%4418%31%20%
2470
December1st to 10thNight
23%39%23%28%14%
2470
11th to 20thNight
24%46%20%32%14%
3037
21st to endNight
22%5%8%22%29%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
10%13%41%27%8%1
270
11th to 20thDay
12%18%33%26%10%1
270
21st to endDay
9%10%41%29%9%1
297
February1st to 10thDay
11%13%37%29%9%
270
11th to 20thDay
13%11%44%22%8%3
252
21st to endDay
11%17%40%28%5%
198
March1st to 10thDay
9%12%45%29%5%
240
11th to 20thDay
17%17%34%21%8%3
240
21st to endDay
13%14%41%22%8%1
318
April1st to 10thDay
7%21%46%20%6%
420
11th to 20thDay
14%19%43%22%3
412
21st to endDay
12%17%39%23%7%1
456
May1st to 10thDay
10%11%36%32%10%1
603
11th to 20thDay
11%9%30%32%15%3
625
21st to endDay
10%8%33%32%15%2
679
June1st to 10thDay
7%5%24%40%19%4
630
11th to 20thDay
6%328%41%19%3
630
21st to endDay
5%220%40%26%5%
630
July1st to 10thDay
7%11%33%35%13%
621
11th to 20thDay
319%39%39%9%
618
21st to endDay
217%35%45%10%
684
August1st to 10thDay
4114%42%32%6%
504
11th to 20thDay
9%115%35%29%11%
437
21st to endDay
8%13%39%33%6%
495
September1st to 10thDay
7%114%39%31%8%
410
11th to 20thDay
4215%41%33%5%
270
21st to endDay
12%320%35%23%6%
270
October1st to 10thDay
14%327%34%20%3
270
11th to 20thDay
6%10%27%37%17%3
270
21st to endDay
19%6%34%21%16%4
297
November1st to 10thDay
11%8%32%28%17%3
270
11th to 20thDay
9%7%36%34%11%4
270
21st to endDay
16%17%31%20%13%3
270
December1st to 10thDay
8%11%39%31%9%1
270
11th to 20thDay
9%12%36%34%8%1
270
21st to endDay
16%17%37%23%6%
297
January1st to 10thNight
6%11%33%41%9%
950
11th to 20thNight
9%10%32%39%10%1
950
21st to endNight
7%8%34%42%9%
868
February1st to 10thNight
10%11%33%37%8%1
760
11th to 20thNight
10%12%37%34%7%
722
21st to endNight
9%13%40%35%4
592
March1st to 10thNight
9%14%36%36%5%
720
11th to 20thNight
14%12%33%32%8%
601
21st to endNight
9%14%42%31%4
594
April1st to 10thNight
7%12%42%36%3
540
11th to 20thNight
10%13%45%29%3
533
21st to endNight
10%13%35%36%6%
540
May1st to 10thNight
10%9%37%39%6%
540
11th to 20thNight
10%9%32%36%12%1
531
21st to endNight
9%437%38%11%1
584
June1st to 10thNight
6%429%45%16%
540
11th to 20thNight
5%337%45%11%
540
21st to endNight
4223%48%22%1
540
July1st to 10thNight
7%112%43%34%2
525
11th to 20thNight
4113%43%38%2
522
21st to endNight
216%45%44%2
591
August1st to 10thNight
411%43%41%1
537
11th to 20thNight
6%111%45%36%1
534
21st to endNight
5%10%41%42%2
594
September1st to 10thNight
7%113%42%34%2
540
11th to 20thNight
12%215%46%25%1
540
21st to endNight
8%321%41%26%1
540
October1st to 10thNight
11%5%23%44%17%1
540
11th to 20thNight
11%6%29%41%14%1
540
21st to endNight
8%8%27%35%20%1
933
November1st to 10thNight
7%6%27%45%14%1
925
11th to 20thNight
6%9%31%39%14%
950
21st to endNight
11%10%28%37%13%1
950
December1st to 10thNight
8%10%32%39%10%
950
11th to 20thNight
11%10%35%35%8%
950
21st to endNight
11%11%34%36%7%1
1045
Page generated at 2024-02-12 05:35:36. Version ac07

Copyright 2024 Attilla Danko


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