Kemmerer
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Kemmerer clear sky chart from 2005-11-06 to 2024-03-18.

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
54%
24844
21%
80490
17%
24759
59%
24759
33%
46232

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
48%
808
16%
4157
14%
798
53%
798
17%
2469
January11th to 20thNight
44%
758
17%
4080
14%
740
53%
740
16%
2369
January21st to endNight
44%
825
12%
4473
15%
814
51%
814
14%
3131
February1st to 10thNight
34%
760
16%
2470
10%
760
44%
760
24%
1514
February11th to 20thNight
45%
741
18%
2403
13%
740
53%
740
29%
1404
February21st to endNight
42%
628
19%
1919
13%
628
50%
628
30%
1156
March1st to 10thNight
45%
760
19%
2097
13%
760
51%
760
31%
1319
March11th to 20thNight
56%
752
20%
2068
15%
752
61%
752
38%
1215
March21st to endNight
43%
792
17%
2178
10%
792
48%
792
31%
1366
April1st to 10thNight
43%
634
17%
1894
11%
634
50%
634
30%
1146
April11th to 20thNight
42%
533
22%
1700
15%
533
50%
533
31%
987
April21st to endNight
47%
540
24%
1620
15%
540
55%
540
34%
923
May1st to 10thNight
48%
540
19%
1620
13%
540
52%
540
31%
976
May11th to 20thNight
61%
531
19%
1595
17%
531
62%
531
32%
959
May21st to endNight
54%
583
17%
1565
13%
582
57%
582
35%
964
June1st to 10thNight
60%
540
21%
1440
16%
540
65%
540
45%
795
June11th to 20thNight
55%
540
24%
1440
17%
540
62%
540
51%
748
June21st to endNight
68%
540
27%
1440
24%
540
72%
540
59%
731
July1st to 10thNight
74%
525
23%
1415
20%
525
77%
525
52%
745
July11th to 20thNight
74%
522
25%
1566
24%
522
77%
522
50%
764
July21st to endNight
77%
591
26%
1674
26%
558
79%
558
52%
821
August1st to 10thNight
74%
537
27%
1602
24%
534
75%
534
45%
832
August11th to 20thNight
79%
534
35%
1602
30%
534
80%
534
55%
763
August21st to endNight
79%
594
36%
1842
33%
594
81%
594
52%
870
September1st to 10thNight
70%
554
35%
1814
32%
554
77%
554
54%
813
September11th to 20thNight
73%
720
32%
1980
25%
720
77%
720
53%
1016
September21st to endNight
69%
720
34%
1980
24%
720
74%
720
53%
1016
October1st to 10thNight
60%
720
27%
2128
19%
720
65%
720
43%
1151
October11th to 20thNight
58%
720
31%
2160
21%
720
67%
720
44%
1119
October21st to endNight
55%
792
29%
2376
20%
792
62%
792
42%
1241
November1st to 10thNight
55%
740
26%
2363
20%
740
62%
740
37%
1272
November11th to 20thNight
49%
888
22%
2598
15%
888
55%
888
36%
1466
November21st to endNight
48%
950
22%
2660
15%
950
56%
950
37%
1521
December1st to 10thNight
41%
950
15%
2660
9%
950
46%
950
29%
1698
December11th to 20thNight
43%
948
17%
3155
11%
948
47%
948
23%
1989
December21st to endNight
34%
1034
8%
4756
7%
1026
40%
1026
14%
2963

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
35%25%6%45%6%6%9%50%
78794
Night
3425%6%35%5%6%9%51%
81055
TransparencyDay
28%9%15%22%18%8%
78515
Night
28%9%16%23%17%7%
80856
SeeingDay
5%12%28%31%18%6%
14549
Night
5%8%27%38%20%2
24888

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
1338%8%5%8%8%8%11%36%
2772
11th to 20thDay
1328%8%5%7%8%8%11%38%
2860
21st to endDay
17%5%9%11%6%6%7%6%9%33%
3146
February1st to 10thDay
15%48%7%5%5%5%6%12%41%
1710
11th to 20thDay
16%47%7%45%6%7%10%43%
1665
21st to endDay
16%37%6%47%8%6%11%42%
1532
March1st to 10thDay
16%26%6%35%6%9%11%44%
2081
11th to 20thDay
26%35%6%46%6%9%10%42%
2058
21st to endDay
37%46%5%45%7%7%9%42%
2178
April1st to 10thDay
36%26%5%5%5%7%8%10%44%
2065
11th to 20thDay
37%36%7%46%6%6%8%43%
2204
21st to endDay
47%26%5%36%6%8%9%44%
2340
May1st to 10thDay
6%7%35%6%45%6%7%9%42%
2340
11th to 20thDay
6%7%25%6%46%7%7%9%41%
2301
21st to endDay
7%6%36%7%5%6%6%7%9%38%
2711
June1st to 10thDay
4425%5%35%5%6%9%53%
2520
11th to 20thDay
442443445%7%59%
2520
21st to endDay
2213333347%68%
2520
July1st to 10thDay
3322425%5%6%7%61%
2500
11th to 20thDay
431342446%8%61%
2340
21st to endDay
5%213435%6%6%8%58%
2545
August1st to 10thDay
42135%25%5%5%7%59%
2328
11th to 20thDay
331233345%7%66%
2299
21st to endDay
33233245%5%7%64%
2513
September1st to 10thDay
4212323446%68%
2142
11th to 20thDay
321443445%7%64%
1980
21st to endDay
4313423445%67%
1980
October1st to 10thDay
6%5%3443446%7%56%
1832
11th to 20thDay
24244245%5%7%60%
1800
21st to endDay
15%26%43446%9%56%
1980
November1st to 10thDay
45%26%6%335%7%9%51%
1713
11th to 20thDay
25%26%6%35%5%7%11%50%
1559
21st to endDay
25%36%5%35%5%7%9%50%
1520
December1st to 10thDay
15%47%7%46%7%7%9%44%
1520
11th to 20thDay
25%46%7%46%8%10%11%36%
1926
21st to endDay
25%37%9%5%8%8%7%9%37%
2794
January1st to 10thNight
15%38%8%46%6%7%10%43%
4211
11th to 20thNight
1327%8%5%6%7%8%13%40%
4110
21st to endNight
18%49%11%7%5%5%7%9%34%
4521
February1st to 10thNight
1338%7%46%6%8%11%44%
2470
11th to 20thNight
2436%5%36%6%6%10%49%
2402
21st to endNight
15%36%7%35%6%8%10%45%
1919
March1st to 10thNight
25%36%5%46%6%7%11%46%
2097
11th to 20thNight
26%245%36%5%7%10%51%
2068
21st to endNight
47%36%6%35%5%7%9%46%
2178
April1st to 10thNight
36%35%5%46%6%6%8%49%
1894
11th to 20thNight
5%6%35%4246%7%9%48%
1700
21st to endNight
45%35%5%345%7%9%51%
1620
May1st to 10thNight
7%5%25%5%35%5%5%9%48%
1620
11th to 20thNight
8%6%25%445%6%6%8%47%
1594
21st to endNight
7%5%35%5%35%6%6%9%46%
1565
June1st to 10thNight
43145%35%45%8%58%
1440
11th to 20thNight
342322336%7%64%
1440
21st to endNight
3314323435%69%
1440
July1st to 10thNight
33133345%6%8%60%
1455
11th to 20thNight
33134245%6%7%61%
1620
21st to endNight
3214425%5%5%8%61%
1773
August1st to 10thNight
4315%5%245%7%8%56%
1611
11th to 20thNight
331342345%7%66%
1602
21st to endNight
321332445%6%66%
1842
September1st to 10thNight
3213412346%70%
1814
11th to 20thNight
32123245%5%7%64%
1980
21st to endNight
5%212423335%70%
1980
October1st to 10thNight
6%5%14434346%60%
2128
11th to 20thNight
45%2442435%7%61%
2160
21st to endNight
3425%42446%8%58%
2376
November1st to 10thNight
3423335%5%7%10%56%
2363
11th to 20thNight
13245%35%6%8%10%53%
2598
21st to endNight
25%25%5%35%5%6%8%54%
2660
December1st to 10thNight
25%36%7%45%5%7%9%47%
2660
11th to 20thNight
25%47%6%46%7%7%9%42%
3271
21st to endNight
15%37%8%6%8%7%7%9%38%
4873

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
34%17%22%20%6%1
2773
11th to 20thDay
33%16%24%18%7%1
2860
21st to endDay
47%11%22%15%42
3146
February1st to 10thDay
35%13%23%19%9%1
1710
11th to 20thDay
32%15%20%23%8%2
1674
21st to endDay
33%11%20%22%12%2
1532
March1st to 10thDay
30%11%22%27%10%1
2081
11th to 20thDay
31%12%22%22%12%1
2058
21st to endDay
35%10%23%21%9%1
2178
April1st to 10thDay
31%11%22%21%13%3
2065
11th to 20thDay
35%10%15%26%13%
2207
21st to endDay
32%9%14%28%16%1
2340
May1st to 10thDay
35%8%14%25%17%2
2340
11th to 20thDay
33%9%15%26%14%4
2304
21st to endDay
38%9%15%25%12%1
2711
June1st to 10thDay
25%7%16%24%23%4
2520
11th to 20thDay
23%6%10%19%28%14%
2520
21st to endDay
16%47%17%33%24%
2520
July1st to 10thDay
19%5%9%19%26%22%
2432
11th to 20thDay
20%48%15%26%27%
2271
21st to endDay
21%6%9%15%27%22%
2404
August1st to 10thDay
21%6%9%19%24%21%
2313
11th to 20thDay
17%5%8%18%31%21%
2299
21st to endDay
19%5%8%15%35%18%
2513
September1st to 10thDay
17%48%18%31%22%
2142
11th to 20thDay
19%5%8%23%28%16%
1980
21st to endDay
19%5%8%24%37%7%
1980
October1st to 10thDay
28%6%12%27%23%5%
1832
11th to 20thDay
22%7%14%33%20%4
1800
21st to endDay
23%7%19%29%19%2
1980
November1st to 10thDay
28%10%15%28%17%3
1713
11th to 20thDay
26%10%21%26%16%2
1559
21st to endDay
28%8%18%29%16%1
1520
December1st to 10thDay
33%14%23%17%11%2
1520
11th to 20thDay
35%14%23%19%10%1
1924
21st to endDay
37%14%17%15%9%7%
2794
January1st to 10thNight
32%16%22%19%10%1
4211
11th to 20thNight
29%18%26%17%9%1
4110
21st to endNight
46%13%18%16%5%2
4521
February1st to 10thNight
30%14%22%25%8%1
2470
11th to 20thNight
28%12%20%24%14%2
2403
21st to endNight
30%11%20%25%13%2
1919
March1st to 10thNight
31%11%20%27%11%1
2097
11th to 20thNight
27%9%21%28%15%1
2068
21st to endNight
34%8%21%28%8%1
2178
April1st to 10thNight
31%9%19%21%14%6%
1894
11th to 20thNight
31%8%16%29%16%1
1700
21st to endNight
28%8%17%31%17%
1620
May1st to 10thNight
33%8%13%25%19%2
1620
11th to 20thNight
32%8%14%28%15%3
1595
21st to endNight
31%8%17%29%13%2
1565
June1st to 10thNight
22%7%18%23%26%5%
1440
11th to 20thNight
19%5%11%23%28%14%
1440
21st to endNight
17%46%13%31%29%
1440
July1st to 10thNight
19%6%9%16%25%25%
1415
11th to 20thNight
19%48%16%24%29%
1566
21st to endNight
18%5%10%16%26%25%
1674
August1st to 10thNight
23%5%9%21%20%22%
1602
11th to 20thNight
17%47%19%30%22%
1602
21st to endNight
18%47%18%32%21%
1842
September1st to 10thNight
16%37%17%29%27%
1814
11th to 20thNight
18%6%10%20%28%17%
1980
21st to endNight
20%47%25%35%9%
1980
October1st to 10thNight
25%6%11%29%24%6%
2128
11th to 20thNight
23%411%33%24%5%
2160
21st to endNight
22%6%18%32%19%3
2376
November1st to 10thNight
23%9%17%27%21%3
2363
11th to 20thNight
23%10%22%30%13%2
2598
21st to endNight
26%8%17%29%18%3
2660
December1st to 10thNight
33%11%22%21%10%4
2660
11th to 20thNight
34%12%20%24%10%
3272
21st to endNight
38%13%17%18%8%6%
4873

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
8%19%20%31%18%5%
270
11th to 20thDay
418%27%30%19%2
270
21st to endDay
311%32%34%16%3
297
February1st to 10thDay
326%37%26%6%1
270
11th to 20thDay
122%34%27%11%3
270
21st to endDay
221%38%31%7%1
344
March1st to 10thDay
317%37%31%9%3
460
11th to 20thDay
5%11%32%36%15%1
449
21st to endDay
9%18%33%31%8%1
462
April1st to 10thDay
8%19%29%27%14%3
420
11th to 20thDay
7%23%33%25%9%2
412
21st to endDay
9%23%26%20%18%4
420
May1st to 10thDay
9%17%31%27%11%4
423
11th to 20thDay
12%11%25%33%13%5%
448
21st to endDay
9%11%25%25%22%7%
666
June1st to 10thDay
48%24%31%25%8%
630
11th to 20thDay
6%12%29%34%17%3
630
21st to endDay
26%29%32%25%6%
630
July1st to 10thDay
35%17%40%28%8%
602
11th to 20thDay
4429%35%21%7%
444
21st to endDay
5%317%38%26%10%
487
August1st to 10thDay
5%424%33%27%7%
447
11th to 20thDay
3423%34%27%9%
437
21st to endDay
3423%34%25%11%
495
September1st to 10thDay
47%24%30%22%14%
450
11th to 20thDay
5%8%31%26%18%12%
450
21st to endDay
6%11%25%29%22%8%
450
October1st to 10thDay
7%9%26%25%22%12%
302
11th to 20thDay
419%23%28%17%10%
270
21st to endDay
7%18%29%30%13%3
297
November1st to 10thDay
8%16%28%27%14%6%
270
11th to 20thDay
5%16%28%36%11%4
270
21st to endDay
313%32%31%17%4
270
December1st to 10thDay
414%31%29%19%3
270
11th to 20thDay
318%29%35%13%1
270
21st to endDay
6%16%35%24%12%6%
297
January1st to 10thNight
313%28%35%19%2
822
11th to 20thNight
314%31%32%19%2
760
21st to endNight
49%34%37%14%2
836
February1st to 10thNight
314%39%32%10%2
760
11th to 20thNight
410%34%37%13%2
744
21st to endNight
49%37%38%10%1
628
March1st to 10thNight
49%32%40%13%2
760
11th to 20thNight
36%27%47%16%1
752
21st to endNight
6%8%35%37%12%1
792
April1st to 10thNight
7%10%34%35%13%1
634
11th to 20thNight
7%12%35%35%10%2
533
21st to endNight
6%11%29%36%16%2
540
May1st to 10thNight
8%8%28%38%16%1
540
11th to 20thNight
9%6%19%38%24%3
531
21st to endNight
8%7%24%31%27%3
584
June1st to 10thNight
5%7%22%38%26%3
540
11th to 20thNight
5%8%28%42%17%
540
21st to endNight
3222%44%27%2
540
July1st to 10thNight
4113%43%37%2
525
11th to 20thNight
3215%48%31%2
522
21st to endNight
319%45%39%3
591
August1st to 10thNight
3212%47%34%2
537
11th to 20thNight
319%49%36%2
534
21st to endNight
3112%41%38%5%
594
September1st to 10thNight
4318%41%31%4
554
11th to 20thNight
3316%38%33%6%
720
21st to endNight
6%318%34%30%9%
720
October1st to 10thNight
7%5%23%36%24%4
720
11th to 20thNight
7%9%22%35%24%3
720
21st to endNight
5%8%27%37%20%3
792
November1st to 10thNight
38%29%37%20%2
740
11th to 20thNight
313%30%38%15%2
888
21st to endNight
411%30%35%17%2
950
December1st to 10thNight
5%13%34%37%11%1
950
11th to 20thNight
49%33%41%11%1
950
21st to endNight
414%36%34%10%2
1045
Page generated at 2024-03-15 12:01:45. Version ac07

Copyright © 2024 Attilla Danko.


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