Taylor University Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Taylor University Observatory clear sky chart from 2005-11-06 to 2024-08-15.

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
36%
25004
16%
92164
11%
24810
43%
24810
18%
62210

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
16%
943
9%
4396
5%
926
23%
926
7%
3419
January11th to 20thNight
14%
949
8%
4406
4%
930
20%
930
7%
3713
January21st to endNight
16%
936
7%
4676
4%
918
23%
918
6%
3786
February1st to 10thNight
19%
760
12%
2338
6%
760
26%
760
13%
1784
February11th to 20thNight
21%
739
13%
2219
6%
739
28%
739
16%
1613
February21st to endNight
18%
628
13%
1884
3%
628
26%
628
14%
1410
March1st to 10thNight
25%
758
17%
3694
8%
745
31%
745
11%
2439
March11th to 20thNight
27%
756
23%
3495
9%
740
35%
740
16%
1924
March21st to endNight
25%
792
10%
3661
7%
776
33%
776
12%
2361
April1st to 10thNight
30%
570
17%
1900
9%
570
40%
570
20%
1271
April11th to 20thNight
33%
563
19%
1854
12%
563
41%
563
21%
1231
April21st to endNight
29%
570
17%
1710
7%
570
39%
570
22%
1174
May1st to 10thNight
30%
565
15%
2766
7%
559
35%
559
11%
1927
May11th to 20thNight
43%
549
14%
2762
13%
541
48%
541
15%
1680
May21st to endNight
53%
605
12%
2969
10%
593
59%
593
20%
1646
June1st to 10thNight
53%
570
19%
1520
13%
570
59%
570
37%
945
June11th to 20thNight
55%
570
21%
1520
14%
570
61%
570
36%
936
June21st to endNight
56%
570
18%
1520
13%
570
60%
570
34%
963
July1st to 10thNight
61%
543
20%
2305
15%
535
64%
535
23%
1321
July11th to 20thNight
67%
540
19%
2203
18%
533
71%
533
31%
1104
July21st to endNight
66%
606
15%
2667
17%
569
69%
569
21%
1605
August1st to 10thNight
68%
567
22%
1690
19%
564
71%
564
35%
991
August11th to 20thNight
67%
549
24%
1665
21%
549
71%
549
35%
969
August21st to endNight
68%
594
22%
1980
21%
594
72%
594
36%
1079
September1st to 10thNight
61%
576
21%
1836
20%
576
65%
576
31%
1090
September11th to 20thNight
64%
720
31%
1980
25%
720
68%
720
41%
1142
September21st to endNight
54%
720
27%
1980
19%
720
60%
720
37%
1186
October1st to 10thNight
50%
720
26%
1980
19%
720
56%
720
36%
1186
October11th to 20thNight
33%
720
22%
2125
13%
720
43%
720
25%
1380
October21st to endNight
29%
792
19%
2574
13%
792
39%
792
20%
1711
November1st to 10thNight
33%
740
23%
2406
16%
740
44%
740
28%
1442
November11th to 20thNight
28%
760
21%
2470
11%
760
40%
760
19%
1652
November21st to endNight
27%
760
17%
2470
10%
760
36%
760
16%
1776
December1st to 10thNight
20%
760
12%
2470
6%
760
27%
760
13%
1852
December11th to 20thNight
21%
905
11%
3206
5%
904
28%
904
12%
2442
December21st to endNight
14%
1039
6%
4867
4%
1026
20%
1026
6%
4060

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
15%10%48%5%4445%7%34%
95274
Night
15%10%48%5%4435%6%36%
93444
TransparencyDay
48%6%11%21%12%2
95033
Night
49%5%10%21%13%2
93291
SeeingDay
17%10%27%24%16%6%
15291
Night
18%9%29%29%13%1
25109

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
16%17%10%11%5%44345%20%
2527
11th to 20thDay
16%16%9%13%5%6%7%6%5%314%
2530
21st to endDay
28%22%8%11%33223414%
2945
February1st to 10thDay
18%15%6%11%7%5%5%345%22%
1838
11th to 20thDay
16%11%412%7%5%3346%28%
1848
21st to endDay
16%15%5%9%6%44446%27%
1570
March1st to 10thDay
22%19%5%9%33334425%
3120
11th to 20thDay
13%9%37%5%4435%7%39%
3410
21st to endDay
18%11%6%10%6%4435%6%29%
3904
April1st to 10thDay
15%12%48%6%5%5%35%7%32%
2280
11th to 20thDay
18%8%37%44445%7%36%
2273
21st to endDay
20%9%27%5%4346%7%33%
2470
May1st to 10thDay
20%9%28%5%5%5%46%8%28%
4082
11th to 20thDay
19%6%26%44445%8%37%
4081
21st to endDay
11%6%26%5%46%48%9%40%
4539
June1st to 10thDay
10%6%36%6%6%445%8%41%
2660
11th to 20thDay
10%5%26%5%5%5%47%9%43%
2660
21st to endDay
11%5%26%5%5%6%47%9%40%
2660
July1st to 10thDay
13%7%36%5%5%45%7%10%35%
4440
11th to 20thDay
7%425%445%5%7%11%46%
4440
21st to endDay
9%7%27%5%6%6%5%6%9%38%
4634
August1st to 10thDay
7%5%25%45%5%47%10%46%
2457
11th to 20thDay
8%5%26%5%5%6%5%6%9%42%
2331
21st to endDay
9%5%26%4445%7%9%45%
2376
September1st to 10thDay
12%5%27%5%3436%7%46%
2106
11th to 20thDay
10%5%25%5%5%5%45%9%46%
1980
21st to endDay
15%6%2444435%6%48%
1980
October1st to 10thDay
13%6%37%44445%6%45%
1980
11th to 20thDay
14%6%26%45%446%7%41%
1828
21st to endDay
21%9%27%45%435%7%32%
1782
November1st to 10thDay
10%6%26%43445%7%49%
1672
11th to 20thDay
17%13%48%5%44347%33%
1710
21st to endDay
19%13%38%5%4335%432%
1710
December1st to 10thDay
16%18%6%11%5%34245%25%
1710
11th to 20thDay
15%17%6%12%5%4435%425%
1958
21st to endDay
23%21%9%12%5%4434412%
2783
January1st to 10thNight
17%17%9%11%5%4333422%
4428
11th to 20thNight
14%21%7%15%6%5%5%44415%
4440
21st to endNight
26%18%8%9%44323419%
4714
February1st to 10thNight
18%16%5%9%5%5%4345%26%
2338
11th to 20thNight
13%13%411%7%5%4345%32%
2218
21st to endNight
18%14%5%9%5%45%345%28%
1884
March1st to 10thNight
19%13%36%444345%35%
3733
11th to 20thNight
12%8%35%44435%7%44%
3549
21st to endNight
20%8%37%44435%6%36%
3754
April1st to 10thNight
14%10%36%6%4445%7%36%
1900
11th to 20thNight
17%9%26%45%5%45%6%37%
1854
21st to endNight
20%9%26%44446%6%36%
1710
May1st to 10thNight
20%9%38%5%45%46%7%29%
2813
11th to 20thNight
21%7%25%34435%7%39%
2812
21st to endNight
10%5%27%445%46%9%44%
3002
June1st to 10thNight
8%5%26%5%44348%49%
1520
11th to 20thNight
8%6%26%5%35%36%10%47%
1520
21st to endNight
9%5%25%5%45%38%9%45%
1520
July1st to 10thNight
9%5%26%45%435%9%48%
2530
11th to 20thNight
7%31433446%8%56%
2530
21st to endNight
11%7%27%445%46%9%42%
2920
August1st to 10thNight
7%425%5%45%5%6%8%49%
1701
11th to 20thNight
7%426%44435%8%52%
1665
21st to endNight
7%416%44445%8%52%
1980
September1st to 10thNight
13%5%26%43436%7%48%
1836
11th to 20thNight
10%424433348%55%
1980
21st to endNight
12%5%15%43435%7%52%
1980
October1st to 10thNight
10%6%26%33345%6%51%
1980
11th to 20thNight
18%8%36%434346%42%
2125
21st to endNight
20%7%26%5%4435%6%37%
2574
November1st to 10thNight
12%9%35%33335%6%46%
2406
11th to 20thNight
15%11%37%5%4325%7%36%
2470
21st to endNight
18%13%48%5%5%4346%30%
2470
December1st to 10thNight
18%15%6%8%6%4435%6%26%
2470
11th to 20thNight
17%15%6%10%5%44346%25%
3234
21st to endNight
24%19%7%11%5%44345%14%
4884

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
65%5%7%16%6%
2528
11th to 20thDay
74%49%9%5%
2530
21st to endDay
78%26%11%3
2945
February1st to 10thDay
66%49%12%9%1
1838
11th to 20thDay
58%410%20%7%1
1858
21st to endDay
58%5%11%17%6%2
1570
March1st to 10thDay
63%48%17%8%
3120
11th to 20thDay
44%5%10%30%11%1
3410
21st to endDay
56%7%15%18%4
3904
April1st to 10thDay
53%5%11%19%12%1
2280
11th to 20thDay
48%5%10%23%11%3
2273
21st to endDay
50%5%12%20%10%3
2470
May1st to 10thDay
53%7%11%21%8%1
4120
11th to 20thDay
44%7%14%25%9%1
4085
21st to endDay
37%8%12%24%18%2
4552
June1st to 10thDay
40%7%10%25%16%2
2660
11th to 20thDay
37%6%11%25%19%2
2660
21st to endDay
39%7%15%20%15%4
2660
July1st to 10thDay
44%6%13%20%15%2
4371
11th to 20thDay
29%7%15%28%20%1
4365
21st to endDay
40%8%15%17%17%3
4487
August1st to 10thDay
32%7%15%32%13%1
2444
11th to 20thDay
36%8%14%25%15%1
2331
21st to endDay
32%8%13%24%17%6%
2376
September1st to 10thDay
38%5%13%24%17%4
2106
11th to 20thDay
35%6%11%27%19%2
1980
21st to endDay
37%5%10%25%22%2
1980
October1st to 10thDay
39%7%11%25%16%3
1980
11th to 20thDay
40%5%10%25%19%1
1828
21st to endDay
53%410%21%12%1
1782
November1st to 10thDay
35%5%14%27%17%2
1672
11th to 20thDay
53%410%20%11%3
1710
21st to endDay
56%5%10%20%8%1
1710
December1st to 10thDay
64%310%16%7%1
1710
11th to 20thDay
62%48%22%3
1955
21st to endDay
78%46%7%5%
2783
January1st to 10thNight
67%48%14%7%
4428
11th to 20thNight
73%47%12%4
4440
21st to endNight
71%37%14%5%
4714
February1st to 10thNight
61%411%15%8%1
2338
11th to 20thNight
55%411%19%11%1
2219
21st to endNight
59%410%16%9%2
1884
March1st to 10thNight
53%49%23%10%1
3733
11th to 20thNight
39%6%10%28%15%2
3549
21st to endNight
50%5%12%26%7%1
3754
April1st to 10thNight
46%6%11%22%13%1
1900
11th to 20thNight
46%6%10%20%15%4
1854
21st to endNight
46%6%10%22%12%4
1710
May1st to 10thNight
52%8%9%20%9%2
2840
11th to 20thNight
43%7%12%28%9%1
2813
21st to endNight
34%9%14%23%16%3
3010
June1st to 10thNight
35%5%10%28%20%3
1520
11th to 20thNight
31%8%12%26%20%3
1520
21st to endNight
32%9%15%24%16%4
1520
July1st to 10thNight
34%6%11%26%16%6%
2490
11th to 20thNight
24%6%15%29%23%2
2482
21st to endNight
38%7%15%18%18%5%
2827
August1st to 10thNight
30%8%13%28%19%2
1690
11th to 20thNight
31%7%13%27%21%2
1665
21st to endNight
28%6%15%23%22%5%
1980
September1st to 10thNight
35%6%13%23%17%6%
1836
11th to 20thNight
29%5%9%29%26%2
1980
21st to endNight
32%5%11%25%23%4
1980
October1st to 10thNight
32%5%11%28%22%2
1980
11th to 20thNight
43%48%26%18%1
2125
21st to endNight
48%410%23%14%2
2574
November1st to 10thNight
38%410%26%20%2
2406
11th to 20thNight
48%49%21%15%3
2470
21st to endNight
57%311%21%8%
2470
December1st to 10thNight
60%49%17%9%1
2470
11th to 20thNight
60%5%10%18%6%1
3236
21st to endNight
73%49%10%4
4884

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
24%17%36%15%7%1
270
11th to 20thDay
27%19%36%14%5%
270
21st to endDay
32%17%32%15%5%
297
February1st to 10thDay
28%17%34%17%4
270
11th to 20thDay
24%17%38%15%5%1
270
21st to endDay
26%19%40%12%3
225
March1st to 10thDay
23%20%36%18%2
270
11th to 20thDay
25%16%32%20%6%1
416
21st to endDay
30%14%31%18%6%1
506
April1st to 10thDay
19%17%33%20%9%2
460
11th to 20thDay
20%19%28%19%11%3
452
21st to endDay
24%13%32%19%10%2
460
May1st to 10thDay
23%14%30%22%9%3
463
11th to 20thDay
21%7%28%25%12%7%
487
21st to endDay
11%5%29%27%18%9%
566
June1st to 10thDay
11%6%28%29%21%5%
680
11th to 20thDay
12%6%25%32%20%5%
680
21st to endDay
12%7%27%28%19%7%
680
July1st to 10thDay
11%319%27%24%15%
671
11th to 20thDay
6%323%31%24%13%
668
21st to endDay
10%315%32%27%13%
635
August1st to 10thDay
7%415%29%29%16%
486
11th to 20thDay
9%417%29%28%13%
456
21st to endDay
9%415%26%33%13%
495
September1st to 10thDay
14%415%25%32%10%
450
11th to 20thDay
10%415%24%31%17%
450
21st to endDay
16%8%22%23%23%8%
450
October1st to 10thDay
13%5%27%30%18%8%
450
11th to 20thDay
16%18%29%26%10%
414
21st to endDay
28%15%33%21%11
297
November1st to 10thDay
11%14%34%26%11%4
270
11th to 20thDay
26%15%29%20%7%2
270
21st to endDay
29%12%37%19%3
270
December1st to 10thDay
21%22%34%16%7%
270
11th to 20thDay
23%17%39%15%6%1
270
21st to endDay
30%19%33%17%2
297
January1st to 10thNight
23%17%34%22%4
950
11th to 20thNight
25%15%37%19%4
950
21st to endNight
23%16%36%22%3
940
February1st to 10thNight
26%11%34%25%3
760
11th to 20thNight
20%15%38%26%2
743
21st to endNight
26%12%39%19%4
628
March1st to 10thNight
21%14%33%25%7%
760
11th to 20thNight
18%13%38%24%7%1
760
21st to endNight
26%11%31%27%5%1
798
April1st to 10thNight
17%11%36%29%7%1
570
11th to 20thNight
20%11%33%27%8%1
563
21st to endNight
23%8%35%24%8%1
570
May1st to 10thNight
22%8%31%31%8%
570
11th to 20thNight
22%423%32%17%2
561
21st to endNight
10%326%40%19%3
617
June1st to 10thNight
10%325%45%16%1
570
11th to 20thNight
10%324%42%21%1
570
21st to endNight
10%224%37%26%1
570
July1st to 10thNight
10%217%35%32%3
555
11th to 20thNight
8%315%41%30%4
552
21st to endNight
8%313%42%32%2
624
August1st to 10thNight
8%113%44%30%5%
567
11th to 20thNight
7%114%40%32%5%
549
21st to endNight
8%213%33%38%6%
594
September1st to 10thNight
14%313%35%30%5%
576
11th to 20thNight
11%215%34%33%5%
720
21st to endNight
12%5%23%35%22%3
720
October1st to 10thNight
13%6%26%33%19%4
720
11th to 20thNight
21%11%29%27%11%1
720
21st to endNight
22%12%33%25%7%
792
November1st to 10thNight
16%9%37%24%12%1
740
11th to 20thNight
19%16%32%25%7%1
760
21st to endNight
25%14%30%24%7%
760
December1st to 10thNight
25%13%35%22%41
760
11th to 20thNight
25%12%34%23%6%
905
21st to endNight
30%15%32%20%4
1045
Page generated at 2024-08-12 09:52:51. Version ac07

Copyright © 2024 Attilla Danko.


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