Turner Research Station
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Turner Research Station clear sky chart from 2005-11-06 to 2024-01-31.

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
47%
23988
28%
74491
18%
23929
57%
23929
36%
41011

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
34%
948
31%
2458
11%
946
47%
946
39%
1442
January11th to 20thNight
32%
950
29%
2470
10%
950
44%
950
36%
1474
January21st to endNight
32%
1024
31%
2692
12%
1024
43%
1024
34%
1625
February1st to 10thNight
28%
720
28%
2160
11%
720
41%
720
28%
1303
February11th to 20thNight
25%
704
25%
2098
9%
700
37%
700
30%
1234
February21st to endNight
20%
592
29%
1776
6%
592
38%
592
28%
1047
March1st to 10thNight
28%
554
25%
1994
12%
554
43%
554
25%
1159
March11th to 20thNight
30%
540
24%
1980
14%
540
43%
540
26%
1117
March21st to endNight
28%
594
27%
2178
12%
594
47%
594
29%
1150
April1st to 10thNight
28%
540
27%
1980
12%
540
51%
540
31%
1034
April11th to 20thNight
28%
533
24%
1931
13%
533
45%
533
27%
1097
April21st to endNight
30%
540
29%
1620
12%
540
52%
540
34%
938
May1st to 10thNight
32%
540
27%
1620
15%
540
49%
540
34%
916
May11th to 20thNight
38%
531
21%
1594
16%
531
49%
531
33%
945
May21st to endNight
48%
583
24%
1745
16%
582
61%
582
36%
1012
June1st to 10thNight
65%
540
25%
1620
24%
540
72%
540
47%
828
June11th to 20thNight
60%
540
27%
1620
24%
540
70%
540
51%
793
June21st to endNight
70%
540
25%
1620
28%
540
74%
540
43%
868
July1st to 10thNight
70%
525
22%
1575
24%
525
74%
525
41%
882
July11th to 20thNight
84%
522
33%
1566
35%
522
89%
522
62%
703
July21st to endNight
83%
591
30%
1673
33%
558
88%
558
55%
800
August1st to 10thNight
90%
537
36%
1601
40%
534
92%
534
68%
681
August11th to 20thNight
77%
534
31%
1655
34%
534
79%
534
41%
891
August21st to endNight
81%
594
27%
2078
31%
594
83%
594
41%
1029
September1st to 10thNight
72%
540
24%
1980
28%
540
75%
540
36%
1034
September11th to 20thNight
69%
540
23%
1980
26%
540
70%
540
32%
1083
September21st to endNight
71%
540
34%
1980
32%
540
78%
540
42%
952
October1st to 10thNight
70%
540
37%
1980
36%
540
76%
540
47%
885
October11th to 20thNight
51%
688
34%
2128
19%
688
63%
688
42%
1113
October21st to endNight
45%
792
34%
2376
19%
792
56%
792
38%
1310
November1st to 10thNight
51%
740
32%
2220
18%
740
60%
740
40%
1214
November11th to 20thNight
49%
902
29%
2422
15%
902
58%
902
41%
1397
November21st to endNight
36%
950
29%
2470
12%
950
45%
950
33%
1543
December1st to 10thNight
40%
950
33%
2470
13%
950
52%
950
39%
1471
December11th to 20thNight
34%
948
29%
2871
11%
948
44%
948
28%
1752
December21st to endNight
33%
1042
19%
4310
10%
1026
45%
1026
25%
2289

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
10%42443445%7%52%
75073
Night
10%42442345%7%56%
75085
TransparencyDay
32%5%10%21%22%9%
74798
Night
29%5%10%21%23%13%
74880
SeeingDay
12%7%23%30%21%7%
13939
Night
12%7%29%35%15%2
23996

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
11%5%24423445%57%
1707
11th to 20thDay
15%5%13323445%54%
1710
21st to endDay
13%5%34323445%54%
1904
February1st to 10thDay
16%6%34424335%50%
1800
11th to 20thDay
15%7%35%433345%47%
1749
21st to endDay
19%6%13313346%51%
1480
March1st to 10thDay
17%6%25%425%446%45%
1966
11th to 20thDay
14%6%35%435%445%47%
1980
21st to endDay
12%435%5%2345%6%52%
2178
April1st to 10thDay
12%6%25%43445%7%47%
1980
11th to 20thDay
13%5%35%5%35%5%46%47%
1978
21st to endDay
13%424435%45%6%51%
2335
May1st to 10thDay
12%5%26%435%5%5%8%46%
2340
11th to 20thDay
13%6%25%5%45%5%5%8%42%
2302
21st to endDay
12%5%35%6%46%6%8%8%37%
2531
June1st to 10thDay
5%324435%5%6%8%54%
2340
11th to 20thDay
4323435%47%9%55%
2340
21st to endDay
6%323446%6%6%9%52%
2340
July1st to 10thDay
7%425%6%46%6%6%10%44%
2340
11th to 20thDay
4212335%5%6%9%60%
2340
21st to endDay
43244345%7%10%54%
2546
August1st to 10thDay
211232446%8%67%
2328
11th to 20thDay
7%3245%35%5%6%9%51%
2241
21st to endDay
5%3245%35%6%7%8%53%
2278
September1st to 10thDay
9%425%5%4436%7%51%
1980
11th to 20thDay
11%4245%345%6%8%48%
1980
21st to endDay
7%414424448%58%
1980
October1st to 10thDay
6%21442445%6%60%
1980
11th to 20thDay
10%423323335%60%
1813
21st to endDay
13%42333233362%
1980
November1st to 10thDay
12%5%25%423445%55%
1858
11th to 20thDay
7%42342345%8%57%
1753
21st to endDay
14%6%34423335%52%
1710
December1st to 10thDay
13%6%2343345%5%52%
1710
11th to 20thDay
13%7%36%4245%46%47%
2161
21st to endDay
15%6%23423345%54%
3135
January1st to 10thNight
12%5%23323436%58%
2458
11th to 20thNight
14%413412345%58%
2470
21st to endNight
14%42432345%5%54%
2692
February1st to 10thNight
14%6%34423335%53%
2160
11th to 20thNight
16%5%24432336%51%
2098
21st to endNight
17%5%24312346%52%
1776
March1st to 10thNight
14%5%35%43345%8%45%
1994
11th to 20thNight
14%5%2443445%7%49%
1980
21st to endNight
9%424424447%55%
2178
April1st to 10thNight
8%5%2432346%8%55%
1980
11th to 20thNight
11%5%34435%447%51%
1931
21st to endNight
9%5%345%2346%7%53%
1620
May1st to 10thNight
9%4245%2445%10%52%
1620
11th to 20thNight
10%6%244335%6%10%47%
1593
21st to endNight
8%323435%6%7%11%48%
1745
June1st to 10thNight
321442445%9%61%
1620
11th to 20thNight
231332246%9%64%
1620
21st to endNight
33234245%6%9%59%
1620
July1st to 10thNight
6%2244245%7%10%54%
1620
11th to 20thNight
311112335%9%71%
1620
21st to endNight
2212325%5%5%11%62%
1772
August1st to 10thNight
11212249%76%
1611
11th to 20thNight
6%425%32445%9%57%
1655
21st to endNight
421442447%9%58%
2078
September1st to 10thNight
8%3134345%5%9%55%
1980
11th to 20thNight
10%5%25%42346%7%52%
1980
21st to endNight
7%313324448%61%
1980
October1st to 10thNight
6%31232335%6%66%
1980
11th to 20thNight
11%313323245%63%
2128
21st to endNight
13%41331333461%
2376
November1st to 10thNight
10%42332334462%
2220
11th to 20thNight
6%5%24433446%59%
2422
21st to endNight
15%5%24423346%52%
2470
December1st to 10thNight
11%42342345%6%56%
2470
11th to 20thNight
12%7%35%423346%50%
3036
21st to endNight
15%7%2432323456%
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
31%36%19%28%12%
1708
11th to 20thDay
33%36%20%25%12%
1710
21st to endDay
33%46%15%27%15%
1904
February1st to 10thDay
38%46%14%22%15%
1800
11th to 20thDay
39%37%17%21%11%
1759
21st to endDay
37%36%14%22%18%
1480
March1st to 10thDay
41%5%7%13%22%11%
1966
11th to 20thDay
39%5%9%13%22%12%
1980
21st to endDay
35%49%20%21%11%
2178
April1st to 10thDay
38%5%9%19%18%12%
1980
11th to 20thDay
38%6%8%17%20%11%
1978
21st to endDay
36%47%19%25%8%
2335
May1st to 10thDay
37%6%8%22%19%8%
2340
11th to 20thDay
40%7%10%21%19%4
2306
21st to endDay
43%8%12%20%15%2
2531
June1st to 10thDay
26%7%14%27%21%4
2340
11th to 20thDay
26%7%12%31%17%7%
2340
21st to endDay
28%8%13%24%22%6%
2340
July1st to 10thDay
33%9%17%26%13%2
2276
11th to 20thDay
18%6%18%29%24%5%
2271
21st to endDay
21%8%18%35%17%1
2405
August1st to 10thDay
15%5%15%37%25%3
2314
11th to 20thDay
29%8%14%30%16%4
2241
21st to endDay
27%8%13%28%20%4
2278
September1st to 10thDay
33%6%10%21%21%9%
1980
11th to 20thDay
34%7%12%20%19%7%
1980
21st to endDay
25%6%10%22%24%12%
1980
October1st to 10thDay
24%5%10%23%22%15%
1980
11th to 20thDay
28%46%15%27%19%
1813
21st to endDay
29%36%17%26%20%
1980
November1st to 10thDay
34%37%20%24%11%
1858
11th to 20thDay
26%5%9%20%26%14%
1753
21st to endDay
37%4418%23%14%
1710
December1st to 10thDay
34%48%21%22%10%
1710
11th to 20thDay
39%47%13%25%12%
2159
21st to endDay
35%26%16%28%14%
3135
January1st to 10thNight
30%35%18%27%17%
2458
11th to 20thNight
32%36%19%27%14%
2470
21st to endNight
34%35%16%24%18%
2692
February1st to 10thNight
37%46%13%23%18%
2160
11th to 20thNight
36%37%16%25%14%
2098
21st to endNight
36%36%15%19%20%
1776
March1st to 10thNight
38%410%13%24%11%
1994
11th to 20thNight
36%410%15%23%12%
1980
21st to endNight
30%5%11%20%23%11%
2178
April1st to 10thNight
29%5%11%22%19%15%
1980
11th to 20thNight
35%5%9%17%19%15%
1931
21st to endNight
31%6%11%18%26%8%
1620
May1st to 10thNight
29%7%12%23%21%9%
1620
11th to 20thNight
32%7%15%25%17%4
1594
21st to endNight
29%7%16%27%18%2
1746
June1st to 10thNight
20%7%15%33%21%5%
1620
11th to 20thNight
18%6%14%33%22%7%
1620
21st to endNight
22%8%12%27%25%6%
1620
July1st to 10thNight
24%9%17%33%14%2
1575
11th to 20thNight
11%6%16%37%26%5%
1566
21st to endNight
14%7%22%37%18%1
1673
August1st to 10thNight
8%5%16%38%28%5%
1601
11th to 20thNight
26%5%14%30%19%5%
1655
21st to endNight
22%8%15%31%20%4
2078
September1st to 10thNight
27%7%12%23%20%11%
1980
11th to 20thNight
31%6%14%21%20%8%
1980
21st to endNight
22%5%9%25%21%16%
1980
October1st to 10thNight
20%411%27%19%19%
1980
11th to 20thNight
27%39%16%23%23%
2128
21st to endNight
29%35%16%24%23%
2376
November1st to 10thNight
28%48%20%26%15%
2220
11th to 20thNight
28%47%20%24%17%
2422
21st to endNight
36%37%15%25%14%
2470
December1st to 10thNight
30%49%21%23%12%
2470
11th to 20thNight
37%36%12%25%16%
3037
21st to endNight
34%25%15%26%18%
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
16%16%39%22%6%1
270
11th to 20thDay
22%12%39%18%7%2
270
21st to endDay
21%12%39%21%6%
294
February1st to 10thDay
25%15%34%23%3
240
11th to 20thDay
23%15%44%15%3
240
21st to endDay
30%19%34%16%2
198
March1st to 10thDay
24%16%38%18%4
240
11th to 20thDay
22%19%35%20%41
240
21st to endDay
16%15%45%19%5%
264
April1st to 10thDay
21%18%36%21%4
240
11th to 20thDay
18%16%31%30%5%
256
21st to endDay
17%14%40%22%7%1
595
May1st to 10thDay
14%11%37%29%8%1
603
11th to 20thDay
17%5%31%31%14%3
625
21st to endDay
13%5%29%33%16%4
679
June1st to 10thDay
6%118%42%26%7%
630
11th to 20thDay
4122%47%22%5%
630
21st to endDay
5%213%40%30%10%
630
July1st to 10thDay
7%18%36%37%12%
621
11th to 20thDay
2438%44%12%
618
21st to endDay
31336%39%16%
684
August1st to 10thDay
25%35%44%14%
626
11th to 20thDay
8%1338%39%12%
555
21st to endDay
6%2331%36%23%
397
September1st to 10thDay
8%1326%41%21%
270
11th to 20thDay
6%16%22%48%17%
270
21st to endDay
12%16%33%33%14%
270
October1st to 10thDay
3118%39%32%6%
270
11th to 20thDay
11%428%32%21%4
270
21st to endDay
24%8%25%24%16%2
297
November1st to 10thDay
19%434%27%13%3
270
11th to 20thDay
14%11%29%29%16%2
270
21st to endDay
21%13%33%23%8%1
270
December1st to 10thDay
17%6%39%26%9%3
270
11th to 20thDay
18%12%39%23%8%1
270
21st to endDay
22%9%38%22%9%1
297
January1st to 10thNight
15%9%38%30%7%
950
11th to 20thNight
17%13%33%29%7%
950
21st to endNight
16%12%35%31%6%
1024
February1st to 10thNight
18%15%36%27%5%
720
11th to 20thNight
19%13%41%25%3
704
21st to endNight
22%14%43%18%3
592
March1st to 10thNight
18%12%39%27%4
554
11th to 20thNight
17%10%39%27%6%
540
21st to endNight
11%13%46%26%4
594
April1st to 10thNight
9%11%48%27%4
540
11th to 20thNight
13%12%42%26%5%
533
21st to endNight
12%9%47%23%8%1
540
May1st to 10thNight
11%8%45%29%6%1
540
11th to 20thNight
13%438%29%13%2
531
21st to endNight
10%334%38%14%2
584
June1st to 10thNight
4121%49%21%4
540
11th to 20thNight
3229%50%15%1
540
21st to endNight
3217%47%26%4
540
July1st to 10thNight
6%112%47%29%6%
525
11th to 20thNight
39%56%28%4
522
21st to endNight
218%51%35%3
591
August1st to 10thNight
25%54%35%4
537
11th to 20thNight
7%16%44%35%6%
534
21st to endNight
5%5%43%39%7%
594
September1st to 10thNight
10%18%43%33%6%
540
11th to 20thNight
12%17%41%33%5%
540
21st to endNight
9%14%38%34%5%
540
October1st to 10thNight
7%117%45%25%4
540
11th to 20thNight
12%427%38%17%2
688
21st to endNight
16%7%30%31%15%1
792
November1st to 10thNight
12%429%38%15%1
740
11th to 20thNight
9%8%29%38%15%1
902
21st to endNight
17%9%34%28%11%1
950
December1st to 10thNight
14%9%33%35%9%
950
11th to 20thNight
20%8%33%33%6%
950
21st to endNight
18%8%37%30%7%
1045
Page generated at 2024-01-28 04:26:37. Version ac07

Copyright 2024 Attilla Danko


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