Dry Creek View Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Dry Creek View Observatory clear sky chart from 2005-11-06 to 2024-01-14.

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
59%
23917
25%
74396
21%
23872
64%
23872
35%
42269

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
57%
756
17%
2457
19%
756
58%
756
25%
1567
January11th to 20thNight
57%
734
21%
2385
20%
734
60%
734
27%
1485
January21st to endNight
55%
792
21%
2574
21%
792
58%
792
25%
1636
February1st to 10thNight
54%
720
19%
2340
18%
720
59%
720
27%
1453
February11th to 20thNight
53%
700
21%
2152
19%
700
58%
700
29%
1318
February21st to endNight
49%
592
23%
1776
22%
592
54%
592
28%
1133
March1st to 10thNight
51%
720
21%
2048
18%
720
55%
720
28%
1324
March11th to 20thNight
57%
720
25%
1980
20%
720
62%
720
37%
1196
March21st to endNight
47%
792
21%
2178
13%
792
54%
792
29%
1406
April1st to 10thNight
48%
720
21%
1980
14%
720
52%
720
32%
1240
April11th to 20thNight
45%
554
25%
1648
17%
554
51%
554
31%
986
April21st to endNight
51%
540
26%
1620
17%
540
57%
540
33%
934
May1st to 10thNight
49%
540
21%
1620
15%
540
53%
540
28%
991
May11th to 20thNight
61%
531
25%
1595
21%
531
64%
531
40%
881
May21st to endNight
56%
582
20%
1746
16%
582
60%
582
36%
982
June1st to 10thNight
61%
540
27%
1620
22%
540
68%
540
48%
788
June11th to 20thNight
55%
540
28%
1620
22%
540
63%
540
50%
767
June21st to endNight
67%
540
27%
1620
23%
540
73%
540
57%
754
July1st to 10thNight
66%
525
23%
1575
19%
525
72%
525
49%
779
July11th to 20thNight
63%
522
21%
1566
18%
522
66%
522
35%
893
July21st to endNight
66%
591
21%
1674
18%
558
68%
558
33%
981
August1st to 10thNight
66%
537
26%
1602
19%
534
70%
534
43%
841
August11th to 20thNight
70%
534
32%
1602
25%
534
74%
534
47%
817
August21st to endNight
71%
599
36%
1797
30%
599
73%
599
50%
880
September1st to 10thNight
77%
720
34%
1980
25%
720
83%
720
60%
964
September11th to 20thNight
70%
720
35%
1980
26%
720
77%
720
55%
1007
September21st to endNight
71%
720
37%
1980
28%
720
76%
720
55%
1004
October1st to 10thNight
65%
720
30%
2035
23%
720
70%
720
46%
1104
October11th to 20thNight
71%
720
34%
2160
29%
720
76%
720
48%
1086
October21st to endNight
65%
792
37%
2376
29%
792
72%
792
48%
1195
November1st to 10thNight
64%
740
31%
2404
29%
740
69%
740
40%
1237
November11th to 20thNight
64%
760
30%
2470
28%
760
68%
760
40%
1292
November21st to endNight
61%
760
29%
2470
30%
760
63%
760
34%
1381
December1st to 10thNight
60%
760
22%
2470
21%
760
62%
760
31%
1442
December11th to 20thNight
55%
759
21%
2904
19%
758
57%
758
20%
1816
December21st to endNight
44%
825
10%
4392
15%
817
48%
817
12%
2709

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
6%6%35%5%3445%7%53%
74937
Night
6%7%35%5%3445%6%52%
74867
TransparencyDay
30%5%9%19%21%15%
74664
Night
31%5%10%20%21%13%
74662
SeeingDay
8%7%19%30%26%9%
13702
Night
9%419%41%25%3
23939

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
9%12%47%6%24447%40%
1708
11th to 20thDay
7%12%5%7%6%4445%8%39%
1647
21st to endDay
8%12%47%6%345%6%8%37%
1782
February1st to 10thDay
7%12%47%6%25%45%8%40%
1620
11th to 20thDay
8%10%5%8%5%345%5%6%41%
1694
21st to endDay
8%11%5%7%32435%7%44%
1480
March1st to 10thDay
8%10%5%6%5%2445%6%44%
1912
11th to 20thDay
5%10%47%6%346%5%7%44%
1980
21st to endDay
9%12%47%6%35%45%7%37%
2178
April1st to 10thDay
7%8%36%5%35%6%5%6%47%
1980
11th to 20thDay
6%8%46%6%34447%48%
2257
21st to endDay
8%8%25%435%446%51%
2340
May1st to 10thDay
6%6%25%6%35%6%6%6%48%
2340
11th to 20thDay
7%6%25%5%445%6%7%50%
2301
21st to endDay
6%5%25%5%45%6%6%7%49%
2530
June1st to 10thDay
332343445%6%62%
2340
11th to 20thDay
4313312346%68%
2340
21st to endDay
221232334474%
2340
July1st to 10thDay
321242445%7%65%
2340
11th to 20thDay
33245%35%6%6%7%56%
2340
21st to endDay
43236%36%7%7%9%51%
2545
August1st to 10thDay
33134246%6%8%59%
2328
11th to 20thDay
322343445%6%64%
2299
21st to endDay
431343445%7%62%
2554
September1st to 10thDay
3212323346%71%
1980
11th to 20thDay
3313323346%70%
1980
21st to endDay
4312222245%71%
1980
October1st to 10thDay
8%5%23423446%59%
1923
11th to 20thDay
45%13323347%66%
1800
21st to endDay
5%6%23423446%62%
1980
November1st to 10thDay
7%7%25%4345%5%6%53%
1674
11th to 20thDay
8%5%35%42445%7%54%
1710
21st to endDay
6%9%36%5%245%5%6%50%
1710
December1st to 10thDay
9%10%45%433446%48%
1710
11th to 20thDay
7%10%411%7%35%5%6%8%34%
2169
21st to endDay
7%10%47%6%45%5%6%7%38%
3146
January1st to 10thNight
9%11%46%5%3445%7%42%
2457
11th to 20thNight
8%9%5%6%5%34447%46%
2385
21st to endNight
8%10%46%6%335%5%7%42%
2574
February1st to 10thNight
7%10%46%5%445%6%7%43%
2340
11th to 20thNight
7%11%47%5%25%45%5%47%
2151
21st to endNight
5%12%48%5%25%45%6%42%
1776
March1st to 10thNight
8%10%48%6%35%45%7%41%
2048
11th to 20thNight
5%8%35%435%5%5%8%48%
1980
21st to endNight
8%10%46%6%3446%7%44%
2178
April1st to 10thNight
9%9%35%5%345%46%47%
1980
11th to 20thNight
7%9%46%4345%46%48%
1648
21st to endNight
8%7%35%5%3435%8%50%
1620
May1st to 10thNight
9%7%36%6%35%46%6%44%
1620
11th to 20thNight
7%6%2443345%7%55%
1594
21st to endNight
6%6%25%5%35%5%6%8%50%
1746
June1st to 10thNight
5%32343346%7%60%
1620
11th to 20thNight
432332333469%
1620
21st to endNight
23143245%5%5%67%
1620
July1st to 10thNight
3325%4245%6%6%61%
1620
11th to 20thNight
5%5%25%6%36%5%6%8%48%
1620
21st to endNight
5%435%6%46%6%7%9%44%
1773
August1st to 10thNight
5%4244346%6%8%56%
1611
11th to 20thNight
33245%346%6%7%58%
1602
21st to endNight
34134335%6%7%61%
1797
September1st to 10thNight
4312223446%70%
1980
11th to 20thNight
4314423346%67%
1980
21st to endNight
5%31332333471%
1980
October1st to 10thNight
8%42342345%6%60%
2035
11th to 20thNight
4424422435%65%
2160
21st to endNight
5%423423447%62%
2376
November1st to 10thNight
5%7%2442435%6%58%
2404
11th to 20thNight
6%6%25%424445%58%
2470
21st to endNight
6%10%45%423345%54%
2470
December1st to 10thNight
9%10%25%424446%50%
2470
11th to 20thNight
9%10%47%5%345%5%8%41%
3041
21st to endNight
8%12%5%8%6%35%6%5%5%37%
4521

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
43%7%20%20%10%
1709
11th to 20thDay
44%5%17%24%9%1
1647
21st to endDay
42%9%17%22%7%3
1782
February1st to 10thDay
44%5%18%21%10%2
1620
11th to 20thDay
43%5%12%23%15%3
1704
21st to endDay
39%6%10%25%17%3
1480
March1st to 10thDay
39%6%8%25%20%2
1912
11th to 20thDay
37%7%10%27%15%5%
1980
21st to endDay
45%5%9%23%14%4
2178
April1st to 10thDay
35%6%9%23%19%8%
1980
11th to 20thDay
36%5%9%20%23%8%
2260
21st to endDay
33%6%8%22%26%6%
2340
May1st to 10thDay
33%6%8%19%26%8%
2340
11th to 20thDay
31%6%7%20%26%10%
2304
21st to endDay
30%7%9%19%28%8%
2530
June1st to 10thDay
20%46%14%32%24%
2340
11th to 20thDay
18%35%12%28%35%
2340
21st to endDay
13%247%24%49%
2340
July1st to 10thDay
19%46%10%18%44%
2276
11th to 20thDay
24%6%8%14%21%28%
2271
21st to endDay
26%7%11%15%19%23%
2404
August1st to 10thDay
21%5%9%14%21%29%
2313
11th to 20thDay
21%45%11%20%39%
2299
21st to endDay
21%37%14%28%27%
2554
September1st to 10thDay
15%46%12%25%38%
1980
11th to 20thDay
18%5%7%16%25%31%
1980
21st to endDay
18%25%16%33%26%
1980
October1st to 10thDay
27%36%18%31%14%
1923
11th to 20thDay
19%47%22%37%12%
1800
21st to endDay
24%49%30%26%8%
1980
November1st to 10thDay
30%5%11%22%24%8%
1674
11th to 20thDay
29%410%30%23%3
1710
21st to endDay
35%411%26%21%3
1710
December1st to 10thDay
37%5%17%26%10%4
1710
11th to 20thDay
46%8%11%21%12%2
2168
21st to endDay
42%8%14%17%16%4
3146
January1st to 10thNight
41%7%18%23%10%1
2457
11th to 20thNight
40%5%16%24%12%3
2385
21st to endNight
41%6%16%24%10%3
2574
February1st to 10thNight
40%5%14%25%12%3
2340
11th to 20thNight
39%411%23%20%3
2152
21st to endNight
40%5%11%22%17%5%
1776
March1st to 10thNight
42%47%27%18%2
2048
11th to 20thNight
32%5%8%30%20%5%
1980
21st to endNight
39%6%11%24%16%4
2178
April1st to 10thNight
37%49%22%19%9%
1980
11th to 20thNight
36%48%21%24%8%
1648
21st to endNight
32%5%10%22%27%5%
1620
May1st to 10thNight
37%6%8%17%25%7%
1620
11th to 20thNight
27%5%8%20%28%12%
1595
21st to endNight
29%5%10%22%25%8%
1746
June1st to 10thNight
20%47%17%32%21%
1620
11th to 20thNight
18%37%12%24%35%
1620
21st to endNight
16%347%21%49%
1620
July1st to 10thNight
20%5%6%9%16%43%
1575
11th to 20thNight
30%7%8%12%16%28%
1566
21st to endNight
32%7%11%13%17%19%
1674
August1st to 10thNight
23%6%11%17%16%26%
1602
11th to 20thNight
22%47%14%16%37%
1602
21st to endNight
20%5%7%15%25%30%
1797
September1st to 10thNight
16%37%12%23%38%
1980
11th to 20thNight
19%47%18%20%33%
1980
21st to endNight
19%3413%31%30%
1980
October1st to 10thNight
25%48%16%33%15%
2035
11th to 20thNight
22%36%18%39%12%
2160
21st to endNight
22%47%27%32%8%
2376
November1st to 10thNight
26%48%26%26%9%
2404
11th to 20thNight
28%310%30%25%4
2470
21st to endNight
33%37%28%24%4
2470
December1st to 10thNight
35%5%13%29%13%5%
2470
11th to 20thNight
41%6%12%25%13%3
3041
21st to endNight
46%6%13%14%17%3
4521

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
19%8%18%30%18%7%
270
11th to 20thDay
11%7%18%38%20%6%
249
21st to endDay
9%315%40%23%9%
264
February1st to 10thDay
11%6%24%32%20%6%
240
11th to 20thDay
11%9%23%35%19%4
360
21st to endDay
10%9%25%37%17%3
346
March1st to 10thDay
11%11%24%29%20%5%
420
11th to 20thDay
10%10%25%30%19%6%
420
21st to endDay
16%13%29%25%15%2
462
April1st to 10thDay
10%13%22%29%21%5%
420
11th to 20thDay
11%17%27%26%16%3
412
21st to endDay
13%16%23%21%22%5%
420
May1st to 10thDay
6%11%27%32%18%6%
423
11th to 20thDay
8%8%23%27%25%9%
448
21st to endDay
7%10%21%27%24%11%
485
June1st to 10thDay
39%20%34%24%10%
450
11th to 20thDay
5%9%23%23%33%7%
450
21st to endDay
25%20%35%28%9%
450
July1st to 10thDay
2219%36%30%11%
446
11th to 20thDay
5%217%30%37%9%
444
21st to endDay
419%29%40%17%
487
August1st to 10thDay
4219%32%32%11%
447
11th to 20thDay
4315%28%36%14%
437
21st to endDay
4314%29%35%15%
495
September1st to 10thDay
25%13%28%34%18%
450
11th to 20thDay
36%20%27%29%15%
450
21st to endDay
46%18%24%32%16%
450
October1st to 10thDay
7%8%16%30%24%15%
393
11th to 20thDay
46%17%24%31%18%
270
21st to endDay
8%5%14%36%26%10%
297
November1st to 10thDay
9%11%19%23%24%14%
270
11th to 20thDay
5%6%16%35%27%11%
270
21st to endDay
13%412%29%33%9%
270
December1st to 10thDay
12%6%16%36%20%10%
270
11th to 20thDay
12%414%37%29%4
270
21st to endDay
13%9%14%40%20%4
297
January1st to 10thNight
12%415%40%23%6%
760
11th to 20thNight
10%5%14%43%23%5%
734
21st to endNight
14%315%43%22%4
792
February1st to 10thNight
11%322%44%16%4
720
11th to 20thNight
11%421%44%18%2
704
21st to endNight
10%6%22%47%14%1
592
March1st to 10thNight
12%7%23%41%16%1
720
11th to 20thNight
8%421%43%22%2
720
21st to endNight
11%7%27%41%13%1
792
April1st to 10thNight
13%8%24%37%17%1
720
11th to 20thNight
11%8%28%40%12%1
554
21st to endNight
11%8%23%37%19%2
540
May1st to 10thNight
13%7%22%39%18%1
540
11th to 20thNight
8%418%43%24%3
531
21st to endNight
7%6%23%38%24%2
584
June1st to 10thNight
6%6%21%41%25%1
540
11th to 20thNight
48%27%39%22%1
540
21st to endNight
2323%44%26%1
540
July1st to 10thNight
4217%38%37%2
525
11th to 20thNight
5%214%41%35%3
522
21st to endNight
5%114%38%40%2
591
August1st to 10thNight
6%117%46%28%1
537
11th to 20thNight
3115%48%33%1
534
21st to endNight
4214%42%35%3
599
September1st to 10thNight
5%213%37%39%5%
720
11th to 20thNight
3317%36%36%5%
720
21st to endNight
6%315%33%37%7%
720
October1st to 10thNight
8%418%40%28%2
720
11th to 20thNight
5%413%43%30%5%
720
21st to endNight
7%319%38%29%4
792
November1st to 10thNight
6%6%17%39%28%4
740
11th to 20thNight
8%317%46%22%4
760
21st to endNight
10%416%40%25%5%
760
December1st to 10thNight
13%315%46%21%3
760
11th to 20thNight
13%415%43%24%1
760
21st to endNight
18%5%17%42%16%2
836
Page generated at 2024-01-11 02:22:36. Version ac07

Copyright 2024 Attilla Danko


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