This page made possible by the sponsorship of: Sate Consulting LLC.

Whitetail Hollow Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Whitetail Hollow Observatory clear sky chart from 2005-11-06 to 2024-01-15.

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
50%
24211
22%
74409
15%
24156
57%
24156
27%
46672

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%
760
23%
2459
10%
757
45%
757
24%
1510
January11th to 20thNight
35%
740
25%
2404
15%
740
50%
740
25%
1470
January21st to endNight
27%
792
24%
2574
11%
792
45%
792
24%
1591
February1st to 10thNight
36%
720
23%
2205
13%
720
47%
720
26%
1374
February11th to 20thNight
30%
703
22%
2098
9%
699
44%
699
27%
1313
February21st to endNight
31%
592
23%
1772
12%
592
43%
592
26%
1132
March1st to 10thNight
40%
720
28%
1980
15%
720
51%
720
33%
1230
March11th to 20thNight
37%
720
23%
1980
11%
720
47%
720
31%
1239
March21st to endNight
35%
792
22%
2178
9%
792
46%
792
30%
1369
April1st to 10thNight
43%
720
25%
1980
15%
720
51%
720
33%
1202
April11th to 20thNight
44%
711
25%
1879
13%
711
52%
711
36%
1135
April21st to endNight
54%
557
31%
1637
19%
557
63%
557
39%
923
May1st to 10thNight
52%
540
25%
1620
13%
540
61%
540
38%
895
May11th to 20thNight
58%
531
15%
1592
10%
531
62%
531
27%
1028
May21st to endNight
64%
582
20%
1744
14%
582
68%
582
27%
1120
June1st to 10thNight
63%
540
14%
1620
12%
540
64%
540
24%
1101
June11th to 20thNight
68%
540
14%
1620
11%
540
69%
540
28%
1029
June21st to endNight
68%
540
11%
1620
8%
540
70%
540
25%
1098
July1st to 10thNight
68%
525
12%
1575
9%
525
69%
525
22%
1093
July11th to 20thNight
72%
522
10%
1566
8%
522
72%
522
22%
1107
July21st to endNight
72%
591
13%
1672
12%
558
73%
558
24%
1138
August1st to 10thNight
72%
537
11%
1600
11%
534
73%
534
20%
1166
August11th to 20thNight
66%
534
13%
1598
12%
534
66%
534
21%
1137
August21st to endNight
62%
703
13%
2043
12%
703
62%
703
19%
1464
September1st to 10thNight
68%
720
15%
1980
13%
720
68%
720
27%
1343
September11th to 20thNight
61%
720
17%
1980
16%
720
62%
720
27%
1332
September21st to endNight
60%
720
21%
1980
17%
720
64%
720
28%
1324
October1st to 10thNight
59%
720
26%
2006
22%
720
64%
720
34%
1233
October11th to 20thNight
57%
720
32%
2160
28%
720
65%
720
38%
1206
October21st to endNight
54%
792
32%
2376
27%
792
64%
792
36%
1340
November1st to 10thNight
55%
740
29%
2221
24%
740
63%
740
36%
1265
November11th to 20thNight
44%
760
27%
2425
21%
760
55%
760
30%
1413
November21st to endNight
46%
760
27%
2470
20%
760
57%
760
30%
1440
December1st to 10thNight
40%
760
26%
2470
16%
760
53%
760
25%
1506
December11th to 20thNight
38%
759
26%
2916
16%
758
49%
758
23%
1689
December21st to endNight
34%
828
15%
4409
17%
817
43%
817
13%
2717

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
11%5%25%5%45%5%6%8%43%
74929
Night
12%5%25%5%35%5%6%8%45%
74867
TransparencyDay
38%8%12%18%18%6%
74652
Night
37%8%12%18%19%7%
74663
SeeingDay
13%7%22%24%21%13%
14105
Night
13%7%23%33%22%3
24222

By Month

Percentage Cloud Cover SE (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
13%6%25%5%34348%47%
1706
11th to 20thDay
14%7%25%434447%47%
1662
21st to endDay
17%5%24434445%46%
1782
February1st to 10thDay
16%6%36%4345%6%7%40%
1750
11th to 20thDay
17%6%2442445%8%45%
1748
21st to endDay
17%5%25%4345%46%44%
1484
March1st to 10thDay
12%5%24424446%52%
1980
11th to 20thDay
14%5%25%6%345%47%45%
1980
21st to endDay
13%5%35%5%35%45%8%44%
2178
April1st to 10thDay
9%5%25%4446%5%7%49%
1980
11th to 20thDay
13%5%25%42445%8%48%
2028
21st to endDay
6%325%435%46%7%56%
2337
May1st to 10thDay
7%324435%5%6%9%51%
2340
11th to 20thDay
10%5%26%5%45%6%6%8%42%
2301
21st to endDay
10%426%6%46%6%7%9%39%
2531
June1st to 10thDay
9%6%27%6%47%7%8%10%34%
2340
11th to 20thDay
6%4246%46%6%9%11%41%
2340
21st to endDay
5%436%7%5%8%7%9%11%36%
2340
July1st to 10thDay
7%5%36%7%5%7%7%7%11%34%
2340
11th to 20thDay
7%5%36%8%6%8%8%8%11%30%
2340
21st to endDay
7%438%7%5%7%8%8%13%31%
2547
August1st to 10thDay
6%5%37%7%6%8%8%9%14%28%
2327
11th to 20thDay
10%5%26%9%6%7%7%9%10%30%
2303
21st to endDay
12%7%37%7%5%7%7%8%9%28%
2288
September1st to 10thDay
7%437%7%5%7%7%7%10%37%
1980
11th to 20thDay
12%5%26%5%45%5%7%9%40%
1980
21st to endDay
15%6%26%6%44446%42%
1980
October1st to 10thDay
12%5%25%434347%51%
1951
11th to 20thDay
11%32342345%6%57%
1800
21st to endDay
10%324433445%57%
1980
November1st to 10thDay
12%6%24434446%52%
1857
11th to 20thDay
14%6%24323345%54%
1752
21st to endDay
14%5%35%5%335%5%6%47%
1710
December1st to 10thDay
15%6%35%6%245%5%8%41%
1710
11th to 20thDay
16%5%2442335%7%48%
2153
21st to endDay
18%9%35%5%24435%42%
3124
January1st to 10thNight
14%6%36%5%3445%5%46%
2459
11th to 20thNight
15%5%25%5%3445%6%46%
2404
21st to endNight
17%7%24434445%46%
2574
February1st to 10thNight
15%6%25%43445%7%45%
2205
11th to 20thNight
17%6%24424346%47%
2098
21st to endNight
14%5%35%5%35%5%5%6%44%
1772
March1st to 10thNight
11%426%436%5%45%51%
1980
11th to 20thNight
13%5%25%425%45%8%48%
1980
21st to endNight
10%5%25%5%35%5%6%6%48%
2178
April1st to 10thNight
10%425%435%45%8%51%
1980
11th to 20thNight
11%5%245%235%48%51%
1879
21st to endNight
7%3145%3445%8%55%
1637
May1st to 10thNight
6%42443446%9%54%
1620
11th to 20thNight
7%426%6%36%7%8%9%42%
1592
21st to endNight
10%5%25%5%446%6%9%43%
1744
June1st to 10thNight
10%5%36%6%47%6%8%11%34%
1620
11th to 20thNight
7%6%25%6%46%6%6%10%42%
1620
21st to endNight
6%426%5%5%7%8%8%13%35%
1620
July1st to 10thNight
8%6%26%7%46%7%8%12%34%
1620
11th to 20thNight
5%6%37%7%47%8%9%13%31%
1620
21st to endNight
6%5%35%6%46%7%9%13%35%
1771
August1st to 10thNight
7%426%7%49%8%11%13%29%
1611
11th to 20thNight
9%6%47%6%5%6%7%9%12%31%
1598
21st to endNight
10%8%37%7%46%6%7%9%31%
2043
September1st to 10thNight
10%5%25%5%36%6%8%12%37%
1980
11th to 20thNight
10%6%47%5%45%5%6%8%41%
1980
21st to endNight
13%6%36%445%5%5%7%42%
1980
October1st to 10thNight
12%5%25%43335%7%50%
2006
11th to 20thNight
13%414423345%57%
2160
21st to endNight
9%425%5%33446%56%
2376
November1st to 10thNight
12%424423445%55%
2221
11th to 20thNight
14%5%34324346%52%
2425
21st to endNight
14%5%24434347%50%
2470
December1st to 10thNight
14%5%245%345%6%7%45%
2470
11th to 20thNight
17%6%24423445%50%
3042
21st to endNight
17%9%35%5%34446%39%
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
37%49%19%26%5%
1707
11th to 20thDay
38%5%9%17%23%8%
1662
21st to endDay
40%45%17%25%8%
1782
February1st to 10thDay
41%6%9%18%19%7%
1750
11th to 20thDay
38%5%6%18%25%7%
1758
21st to endDay
41%5%8%17%19%11%
1484
March1st to 10thDay
35%5%8%17%22%14%
1980
11th to 20thDay
39%6%11%18%17%9%
1980
21st to endDay
39%6%11%18%20%6%
2178
April1st to 10thDay
34%6%10%19%22%9%
1980
11th to 20thDay
35%5%9%19%20%11%
2028
21st to endDay
27%5%11%26%26%5%
2337
May1st to 10thDay
29%6%13%22%24%6%
2340
11th to 20thDay
38%9%15%20%16%2
2305
21st to endDay
39%9%13%21%16%2
2531
June1st to 10thDay
40%12%17%17%12%1
2340
11th to 20thDay
33%11%19%24%12%1
2340
21st to endDay
38%12%19%17%12%2
2340
July1st to 10thDay
40%13%20%16%7%4
2275
11th to 20thDay
42%15%22%14%5%2
2271
21st to endDay
39%14%21%19%5%1
2405
August1st to 10thDay
41%16%19%18%5%
2314
11th to 20thDay
44%14%17%16%7%1
2303
21st to endDay
47%13%17%14%8%1
2288
September1st to 10thDay
41%11%16%14%14%5%
1980
11th to 20thDay
39%10%11%18%18%5%
1980
21st to endDay
42%6%10%17%18%6%
1980
October1st to 10thDay
34%5%9%21%19%11%
1951
11th to 20thDay
28%5%8%23%27%9%
1800
21st to endDay
29%5%6%16%28%16%
1980
November1st to 10thDay
34%47%16%24%15%
1857
11th to 20thDay
33%37%19%24%13%
1752
21st to endDay
37%49%19%21%9%
1710
December1st to 10thDay
40%6%12%15%19%7%
1710
11th to 20thDay
37%46%18%27%8%
2150
21st to endDay
43%6%7%17%23%4
3124
January1st to 10thNight
40%5%7%19%22%7%
2459
11th to 20thNight
39%5%7%17%24%8%
2404
21st to endNight
41%45%15%24%11%
2574
February1st to 10thNight
40%5%9%18%19%10%
2205
11th to 20thNight
39%48%16%23%10%
2099
21st to endNight
40%6%9%16%17%13%
1772
March1st to 10thNight
35%5%8%17%23%13%
1980
11th to 20thNight
35%6%13%17%20%10%
1980
21st to endNight
35%7%12%18%19%9%
2178
April1st to 10thNight
33%5%10%19%21%11%
1980
11th to 20thNight
32%5%9%20%23%12%
1879
21st to endNight
27%7%12%25%22%7%
1637
May1st to 10thNight
26%7%14%24%21%8%
1620
11th to 20thNight
34%13%17%18%16%2
1593
21st to endNight
35%11%11%21%19%3
1745
June1st to 10thNight
40%11%19%20%10%
1620
11th to 20thNight
35%10%19%23%11%1
1620
21st to endNight
36%15%22%15%10%3
1620
July1st to 10thNight
38%15%20%16%7%3
1575
11th to 20thNight
38%17%23%16%6%1
1566
21st to endNight
35%16%22%20%6%1
1672
August1st to 10thNight
39%19%19%18%6%
1600
11th to 20thNight
42%14%20%17%6%1
1598
21st to endNight
45%12%17%16%8%1
2043
September1st to 10thNight
37%13%18%15%12%5%
1980
11th to 20thNight
39%10%15%15%17%5%
1980
21st to endNight
40%7%13%17%17%5%
1980
October1st to 10thNight
34%6%10%18%23%9%
2006
11th to 20thNight
30%38%21%26%11%
2160
21st to endNight
30%5%6%18%26%15%
2376
November1st to 10thNight
31%5%9%14%25%16%
2221
11th to 20thNight
35%47%15%24%15%
2425
21st to endNight
35%48%19%23%10%
2470
December1st to 10thNight
38%6%11%17%21%7%
2470
11th to 20thNight
37%48%16%26%9%
3044
21st to endNight
45%6%6%17%22%4
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
14%16%48%17%4
270
11th to 20thDay
14%19%33%25%7%2
254
21st to endDay
22%20%41%12%5%
264
February1st to 10thDay
15%18%41%20%6%
240
11th to 20thDay
26%14%39%18%3
240
21st to endDay
17%17%41%17%7%1
202
March1st to 10thDay
15%14%34%25%12%1
420
11th to 20thDay
15%12%37%26%9%1
420
21st to endDay
18%10%37%24%10%1
462
April1st to 10thDay
15%14%28%27%14%2
420
11th to 20thDay
13%13%27%21%19%7%
412
21st to endDay
9%9%26%26%22%8%
420
May1st to 10thDay
7%11%26%30%16%9%
423
11th to 20thDay
10%415%30%23%18%
447
21st to endDay
13%312%25%27%20%
485
June1st to 10thDay
11%114%26%29%19%
450
11th to 20thDay
7%412%19%27%31%
450
21st to endDay
5%111%28%30%24%
450
July1st to 10thDay
7%27%18%35%31%
445
11th to 20thDay
7%1420%34%34%
444
21st to endDay
5%16%25%34%28%
488
August1st to 10thDay
7%29%28%29%24%
446
11th to 20thDay
10%26%18%34%29%
439
21st to endDay
14%28%22%29%26%
495
September1st to 10thDay
8%48%24%36%20%
450
11th to 20thDay
13%413%25%30%14%
450
21st to endDay
18%113%24%29%15%
450
October1st to 10thDay
15%320%31%20%12%
450
11th to 20thDay
11%322%30%22%11%
450
21st to endDay
13%6%23%27%25%5%
495
November1st to 10thDay
15%6%27%25%21%6%
455
11th to 20thDay
19%8%35%27%10%1
312
21st to endDay
11%16%27%29%14%2
270
December1st to 10thDay
17%15%33%26%7%1
270
11th to 20thDay
19%16%34%21%9%1
270
21st to endDay
24%13%33%21%8%2
297
January1st to 10thNight
17%12%37%29%5%
760
11th to 20thNight
18%11%31%31%9%
740
21st to endNight
19%11%40%26%4
792
February1st to 10thNight
17%11%32%33%7%
720
11th to 20thNight
19%11%36%30%4
703
21st to endNight
16%10%39%32%4
592
March1st to 10thNight
13%9%35%38%6%
720
11th to 20thNight
14%10%34%32%9%1
720
21st to endNight
12%12%36%29%11%
792
April1st to 10thNight
12%10%32%35%12%1
720
11th to 20thNight
12%10%29%32%17%
711
21st to endNight
7%6%28%42%17%1
557
May1st to 10thNight
7%6%30%40%16%1
540
11th to 20thNight
8%324%40%22%4
531
21st to endNight
11%411%37%34%4
584
June1st to 10thNight
11%212%40%31%4
540
11th to 20thNight
8%210%36%34%9%
540
21st to endNight
7%110%35%39%8%
540
July1st to 10thNight
8%28%27%46%9%
525
11th to 20thNight
7%2430%48%10%
522
21st to endNight
7%17%33%45%7%
591
August1st to 10thNight
7%17%28%46%11%
537
11th to 20thNight
13%26%29%43%8%
534
21st to endNight
10%39%27%41%10%
703
September1st to 10thNight
11%37%30%43%7%
720
11th to 20thNight
12%211%31%41%3
720
21st to endNight
15%213%34%32%5%
720
October1st to 10thNight
13%417%38%23%5%
720
11th to 20thNight
15%319%34%25%4
720
21st to endNight
10%6%23%35%23%2
792
November1st to 10thNight
14%6%21%35%22%3
740
11th to 20thNight
16%9%26%33%15%1
760
21st to endNight
15%8%26%32%17%1
760
December1st to 10thNight
17%8%29%33%12%1
760
11th to 20thNight
19%9%27%32%12%1
760
21st to endNight
23%11%26%30%9%
836
Page generated at 2024-01-12 16:17:47. Version ac07

Copyright 2024 Attilla Danko


Whitetail Hollow Observatory Clear Sky Chart |Charts Home