Elkhorn Ranch
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Elkhorn Ranch clear sky chart from 2005-11-06 to 2024-01-13.

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
37%
24538
28%
74464
11%
24477
54%
24477
36%
38988

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
28%
950
33%
2647
9%
946
51%
946
40%
1306
January11th to 20thNight
22%
843
35%
2481
10%
843
48%
843
40%
1180
January21st to endNight
25%
792
33%
2574
11%
792
51%
792
38%
1261
February1st to 10thNight
19%
720
30%
2340
8%
720
45%
720
36%
1111
February11th to 20thNight
20%
703
29%
2122
7%
700
43%
700
35%
1087
February21st to endNight
21%
592
37%
1776
7%
592
52%
592
35%
899
March1st to 10thNight
26%
720
29%
2160
8%
720
45%
720
36%
1082
March11th to 20thNight
30%
720
27%
1980
8%
720
44%
720
35%
1144
March21st to endNight
25%
671
29%
2057
6%
671
47%
671
33%
1104
April1st to 10thNight
23%
540
27%
1800
10%
540
45%
540
31%
889
April11th to 20thNight
27%
533
23%
1777
8%
533
45%
533
26%
978
April21st to endNight
29%
540
23%
1800
9%
540
48%
540
26%
1021
May1st to 10thNight
37%
540
21%
1720
12%
540
49%
540
25%
1027
May11th to 20thNight
44%
531
14%
1425
9%
531
50%
531
27%
924
May21st to endNight
45%
584
19%
1552
9%
582
55%
582
35%
898
June1st to 10thNight
58%
540
23%
1440
13%
540
67%
540
44%
774
June11th to 20thNight
48%
540
25%
1440
13%
540
57%
540
48%
769
June21st to endNight
60%
540
24%
1440
17%
540
67%
540
45%
788
July1st to 10thNight
63%
525
18%
1400
13%
525
68%
525
34%
861
July11th to 20thNight
69%
522
25%
1392
17%
522
75%
522
44%
778
July21st to endNight
65%
591
15%
1573
10%
558
69%
558
30%
987
August1st to 10thNight
63%
537
14%
1602
11%
534
66%
534
30%
944
August11th to 20thNight
63%
534
25%
1773
21%
534
72%
534
36%
947
August21st to endNight
62%
594
24%
1980
22%
594
68%
594
32%
1101
September1st to 10thNight
61%
540
29%
1800
22%
540
72%
540
37%
957
September11th to 20thNight
54%
540
33%
1808
23%
540
68%
540
41%
901
September21st to endNight
49%
540
31%
1980
21%
540
63%
540
38%
939
October1st to 10thNight
37%
718
29%
2158
11%
718
51%
718
39%
1148
October11th to 20thNight
42%
720
37%
2160
15%
720
59%
720
52%
977
October21st to endNight
37%
812
36%
2396
13%
812
54%
812
43%
1218
November1st to 10thNight
34%
925
35%
2405
10%
925
51%
925
48%
1210
November11th to 20thNight
27%
950
38%
2470
9%
950
47%
950
46%
1247
November21st to endNight
32%
950
32%
2559
9%
950
51%
950
43%
1335
December1st to 10thNight
29%
950
30%
2660
10%
950
46%
950
38%
1347
December11th to 20thNight
23%
950
29%
3121
6%
949
45%
949
32%
1572
December21st to endNight
19%
1041
20%
4696
6%
1026
41%
1026
21%
2277

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
46%35%5%35%5%6%8%51%
74768
Night
35%2442445%8%59%
74980
TransparencyDay
29%7%12%22%22%8%
74478
Night
23%6%13%26%24%8%
74792
SeeingDay
13%16%33%26%11%2
14375
Night
7%14%36%30%11%1
24543

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
425%42335%8%66%
1518
11th to 20thDay
15%37%32445%8%58%
1540
21st to endDay
1437%4235%5%8%58%
1782
February1st to 10thDay
6%37%5%2345%7%59%
1620
11th to 20thDay
325%4245%49%61%
1723
21st to endDay
6%26%5%3445%8%58%
1480
March1st to 10thDay
25%36%42445%9%57%
1800
11th to 20thDay
49%35%434448%52%
1975
21st to endDay
29%45%435%5%7%9%48%
2299
April1st to 10thDay
37%245%35%5%6%9%50%
2160
11th to 20thDay
6%10%36%5%45%5%5%7%43%
2131
21st to endDay
7%10%45%6%35%46%7%43%
2160
May1st to 10thDay
8%9%36%5%35%5%6%10%39%
2237
11th to 20thDay
9%9%36%6%45%6%6%9%36%
2468
21st to endDay
6%6%25%5%45%6%8%9%43%
2724
June1st to 10thDay
5%4245%35%6%8%10%47%
2520
11th to 20thDay
5%424435%5%6%9%52%
2520
21st to endDay
4425%6%36%8%7%9%45%
2520
July1st to 10thDay
6%5%25%7%46%7%8%8%42%
2520
11th to 20thDay
6%5%36%7%46%6%8%9%42%
2520
21st to endDay
8%5%36%6%5%8%7%8%9%34%
2648
August1st to 10thDay
8%5%38%8%46%7%8%8%34%
2328
11th to 20thDay
5%425%6%46%6%8%9%44%
2126
21st to endDay
6%436%6%46%6%7%7%45%
2376
September1st to 10thDay
6%5%35%6%45%5%5%6%51%
2160
11th to 20thDay
6%4245%345%5%7%57%
2152
21st to endDay
5%423424446%62%
1979
October1st to 10thDay
5%5%244345%5%6%58%
1800
11th to 20thDay
3323323347%67%
1800
21st to endDay
47%24423446%61%
1940
November1st to 10thDay
131331345%7%68%
1673
11th to 20thDay
132442335%7%65%
1710
21st to endDay
16%25%42435%8%61%
1619
December1st to 10thDay
336%42435%8%60%
1520
11th to 20thDay
142431336%10%61%
1926
21st to endDay
16%37%5%2446%8%55%
2794
January1st to 10thNight
425%423347%66%
2647
11th to 20thNight
132342335%8%67%
2481
21st to endNight
1425%43445%6%62%
2574
February1st to 10thNight
5%35%423338%64%
2340
11th to 20thNight
1436%32335%7%62%
2122
21st to endNight
15%25%43335%6%63%
1776
March1st to 10thNight
15%233245%6%8%60%
2160
11th to 20thNight
36%35%434447%58%
1980
21st to endNight
27%344245%5%7%58%
2057
April1st to 10thNight
26%2432336%6%62%
1800
11th to 20thNight
5%10%3433445%6%55%
1777
21st to endNight
7%10%34424347%52%
1800
May1st to 10thNight
8%6%35%4345%6%9%47%
1720
11th to 20thNight
10%6%245%345%7%9%47%
1424
21st to endNight
5%5%244235%6%9%54%
1552
June1st to 10thNight
3422225%46%11%59%
1440
11th to 20thNight
42224235%5%10%62%
1440
21st to endNight
3214335%6%8%9%57%
1440
July1st to 10thNight
6%4245%346%6%12%49%
1440
11th to 20thNight
2323436%5%6%11%55%
1440
21st to endNight
5%3146%5%7%7%9%11%42%
1666
August1st to 10thNight
4425%446%7%8%9%48%
1611
11th to 20thNight
5%4244345%7%11%52%
1773
21st to endNight
44245%45%5%7%9%52%
1980
September1st to 10thNight
5%324445%6%5%9%54%
1800
11th to 20thNight
6%21332445%7%62%
1808
21st to endNight
5%42442335%7%62%
1980
October1st to 10thNight
5%4234235%5%7%60%
2158
11th to 20thNight
2313223345%72%
2160
21st to endNight
36%24323347%63%
2396
November1st to 10thNight
1212323348%70%
2405
11th to 20thNight
1424323346%69%
2470
21st to endNight
16%2432335%8%63%
2559
December1st to 10thNight
142441445%9%64%
2660
11th to 20thNight
15%3442346%9%59%
3271
21st to endNight
17%37%5%2445%7%54%
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
18%316%31%26%5%
1519
11th to 20thDay
23%5%14%27%24%7%
1540
21st to endDay
25%5%12%31%20%7%
1782
February1st to 10thDay
25%414%30%20%8%
1620
11th to 20thDay
20%413%27%29%7%
1733
21st to endDay
24%5%11%23%26%11%
1480
March1st to 10thDay
24%5%11%28%26%7%
1800
11th to 20thDay
30%6%11%25%23%5%
1975
21st to endDay
31%6%12%25%20%6%
2299
April1st to 10thDay
28%7%13%23%20%9%
2160
11th to 20thDay
39%5%12%19%19%7%
2134
21st to endDay
38%7%10%24%18%3
2160
May1st to 10thDay
40%7%11%21%17%3
2237
11th to 20thDay
42%11%13%20%12%2
2472
21st to endDay
34%8%14%19%17%8%
2724
June1st to 10thDay
28%10%15%19%19%9%
2520
11th to 20thDay
27%8%10%16%21%17%
2520
21st to endDay
30%9%11%19%19%11%
2520
July1st to 10thDay
36%10%12%14%20%9%
2451
11th to 20thDay
34%10%12%21%16%6%
2445
21st to endDay
43%11%18%15%10%2
2501
August1st to 10thDay
43%10%14%14%13%5%
2313
11th to 20thDay
32%10%12%18%19%9%
2126
21st to endDay
34%8%11%19%21%6%
2376
September1st to 10thDay
32%6%10%16%23%13%
2160
11th to 20thDay
27%5%10%18%28%12%
2152
21st to endDay
23%5%7%22%34%9%
1979
October1st to 10thDay
26%6%10%21%26%11%
1800
11th to 20thDay
19%39%22%34%13%
1800
21st to endDay
24%48%25%28%11%
1940
November1st to 10thDay
15%412%21%33%15%
1673
11th to 20thDay
18%47%33%29%9%
1710
21st to endDay
22%39%25%28%12%
1619
December1st to 10thDay
21%6%14%27%24%7%
1520
11th to 20thDay
19%5%14%30%26%6%
1924
21st to endDay
26%5%11%23%26%9%
2794
January1st to 10thNight
18%414%32%27%6%
2647
11th to 20thNight
17%314%28%29%8%
2481
21st to endNight
22%412%29%26%7%
2574
February1st to 10thNight
21%314%33%22%7%
2340
11th to 20thNight
22%411%30%26%7%
2122
21st to endNight
21%48%28%28%10%
1776
March1st to 10thNight
19%5%12%26%31%6%
2160
11th to 20thNight
27%6%9%29%24%6%
1980
21st to endNight
26%5%13%27%24%4
2057
April1st to 10thNight
23%5%12%29%24%8%
1800
11th to 20thNight
30%6%11%28%20%5%
1777
21st to endNight
32%6%12%28%19%3
1800
May1st to 10thNight
34%8%12%26%17%4
1720
11th to 20thNight
33%12%19%21%13%2
1425
21st to endNight
27%7%19%23%18%6%
1552
June1st to 10thNight
21%6%22%26%15%10%
1440
11th to 20thNight
17%9%12%21%23%17%
1440
21st to endNight
22%7%14%23%23%10%
1440
July1st to 10thNight
30%10%17%19%17%8%
1400
11th to 20thNight
23%8%15%31%17%6%
1392
21st to endNight
31%13%25%21%9%2
1573
August1st to 10thNight
29%12%23%19%13%4
1602
11th to 20thNight
28%6%15%25%20%6%
1773
21st to endNight
28%9%15%26%18%5%
1980
September1st to 10thNight
26%7%13%22%22%10%
1800
11th to 20thNight
22%7%13%22%23%13%
1808
21st to endNight
23%5%10%25%30%8%
1980
October1st to 10thNight
22%7%12%23%25%11%
2158
11th to 20thNight
14%310%23%35%14%
2160
21st to endNight
22%410%27%28%10%
2396
November1st to 10thNight
15%411%25%32%13%
2405
11th to 20thNight
16%49%31%30%10%
2470
21st to endNight
20%49%25%30%11%
2559
December1st to 10thNight
18%5%15%27%25%9%
2660
11th to 20thNight
21%5%13%26%28%7%
3272
21st to endNight
27%5%11%22%26%9%
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
13%20%33%23%10%1
270
11th to 20thDay
10%24%42%20%4
246
21st to endDay
6%19%49%21%5%1
264
February1st to 10thDay
11%35%38%13%21
240
11th to 20thDay
10%33%40%16%1
240
21st to endDay
16%22%41%20%11
198
March1st to 10thDay
13%21%43%19%4
240
11th to 20thDay
18%23%34%21%4
415
21st to endDay
20%24%36%15%4
462
April1st to 10thDay
16%26%33%19%5%1
420
11th to 20thDay
27%27%27%15%31
412
21st to endDay
23%23%32%15%6%1
420
May1st to 10thDay
17%20%39%18%6%1
500
11th to 20thDay
19%12%31%27%9%2
625
21st to endDay
15%15%31%24%14%2
679
June1st to 10thDay
10%12%32%29%16%3
630
11th to 20thDay
10%13%34%29%11%2
630
21st to endDay
9%10%33%31%15%2
630
July1st to 10thDay
7%426%40%18%5%
621
11th to 20thDay
8%422%36%23%6%
618
21st to endDay
12%418%38%23%5%
590
August1st to 10thDay
12%5%30%31%18%4
447
11th to 20thDay
8%6%31%38%14%3
437
21st to endDay
12%6%31%35%13%2
495
September1st to 10thDay
12%12%31%30%13%3
450
11th to 20thDay
8%11%37%29%12%2
442
21st to endDay
9%15%28%28%16%4
270
October1st to 10thDay
12%18%29%21%17%4
270
11th to 20thDay
10%24%33%24%8%1
270
21st to endDay
13%18%39%22%7%1
297
November1st to 10thDay
16%18%37%17%11%1
270
11th to 20thDay
12%23%37%22%6%1
270
21st to endDay
11%19%40%22%6%1
270
December1st to 10thDay
16%19%39%21%5%1
270
11th to 20thDay
11%21%42%19%6%
270
21st to endDay
14%26%35%17%6%2
297
January1st to 10thNight
5%23%38%27%7%2
950
11th to 20thNight
6%23%44%20%6%1
843
21st to endNight
316%50%26%5%
792
February1st to 10thNight
5%23%50%19%3
720
11th to 20thNight
5%21%48%21%4
704
21st to endNight
6%21%46%24%3
592
March1st to 10thNight
7%21%42%24%5%1
720
11th to 20thNight
8%15%44%25%8%
720
21st to endNight
8%17%46%25%4
671
April1st to 10thNight
9%19%43%24%5%
540
11th to 20thNight
13%18%37%25%5%1
533
21st to endNight
14%17%35%26%7%1
540
May1st to 10thNight
11%10%34%34%10%1
540
11th to 20thNight
15%7%27%36%13%1
531
21st to endNight
9%12%27%36%14%2
584
June1st to 10thNight
8%7%22%44%17%2
540
11th to 20thNight
7%7%35%35%14%2
540
21st to endNight
4127%46%19%2
540
July1st to 10thNight
8%118%45%25%3
525
11th to 20thNight
3316%39%34%4
522
21st to endNight
6%114%44%32%3
591
August1st to 10thNight
8%217%41%28%4
537
11th to 20thNight
8%220%46%22%3
534
21st to endNight
7%320%45%22%3
594
September1st to 10thNight
6%322%42%22%4
540
11th to 20thNight
8%329%41%18%2
540
21st to endNight
9%8%29%35%16%3
540
October1st to 10thNight
8%10%41%28%10%3
718
11th to 20thNight
412%39%34%9%3
720
21st to endNight
9%10%40%29%11%1
812
November1st to 10thNight
6%17%40%27%10%
925
11th to 20thNight
7%20%43%21%8%1
950
21st to endNight
6%17%41%27%7%1
950
December1st to 10thNight
7%22%39%27%5%
950
11th to 20thNight
6%20%45%21%6%1
950
21st to endNight
9%22%43%21%41
1045
Page generated at 2024-01-09 23:24:59. Version ac07

Copyright 2024 Attilla Danko


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