NOVAC Turner Mountain
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the NOVAC Turner Mountain 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%
23497
20%
74692
11%
23451
48%
23451
24%
46853

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
17%
757
24%
2552
7%
757
38%
757
21%
1554
January11th to 20thNight
25%
732
22%
2378
10%
732
40%
732
19%
1539
January21st to endNight
18%
792
24%
2574
7%
792
38%
792
22%
1585
February1st to 10thNight
22%
720
17%
2340
6%
720
36%
720
19%
1510
February11th to 20thNight
14%
700
19%
2253
4%
700
33%
700
18%
1434
February21st to endNight
15%
592
24%
1772
6%
592
35%
592
18%
1174
March1st to 10thNight
21%
720
25%
1980
7%
720
39%
720
25%
1230
March11th to 20thNight
24%
720
21%
1980
9%
720
36%
720
22%
1308
March21st to endNight
19%
792
20%
2170
6%
792
31%
792
22%
1447
April1st to 10thNight
24%
720
18%
1800
4%
720
34%
720
24%
1225
April11th to 20thNight
32%
711
21%
1775
7%
711
39%
711
30%
1150
April21st to endNight
33%
720
20%
1800
6%
720
40%
720
28%
1214
May1st to 10thNight
38%
559
16%
1639
8%
559
44%
559
23%
1098
May11th to 20thNight
39%
468
16%
1529
11%
468
45%
468
22%
1023
May21st to endNight
54%
388
16%
1551
15%
388
59%
388
22%
932
June1st to 10thNight
55%
360
18%
1440
19%
360
62%
360
25%
824
June11th to 20thNight
53%
360
16%
1440
17%
360
59%
360
21%
875
June21st to endNight
60%
360
18%
1440
19%
360
66%
360
26%
809
July1st to 10thNight
59%
350
15%
1400
17%
350
62%
350
21%
851
July11th to 20thNight
69%
475
16%
1519
14%
475
71%
475
30%
919
July21st to endNight
65%
591
17%
1672
13%
558
68%
558
33%
1029
August1st to 10thNight
65%
537
16%
1600
12%
534
67%
534
26%
1077
August11th to 20thNight
61%
583
17%
1647
12%
583
63%
583
26%
1119
August21st to endNight
61%
792
18%
1980
12%
792
62%
792
31%
1338
September1st to 10thNight
54%
720
21%
1800
12%
720
58%
720
30%
1231
September11th to 20thNight
59%
720
30%
1803
20%
720
63%
720
37%
1138
September21st to endNight
43%
720
20%
2078
14%
720
49%
720
25%
1394
October1st to 10thNight
47%
720
19%
2160
17%
720
53%
720
28%
1362
October11th to 20thNight
42%
720
26%
2160
19%
720
54%
720
30%
1291
October21st to endNight
36%
792
27%
2376
16%
792
50%
792
29%
1436
November1st to 10thNight
37%
740
27%
2273
16%
740
51%
740
32%
1309
November11th to 20thNight
33%
760
26%
2520
13%
760
50%
760
26%
1454
November21st to endNight
32%
760
23%
2660
13%
760
48%
760
24%
1526
December1st to 10thNight
25%
760
20%
2660
7%
760
41%
760
18%
1671
December11th to 20thNight
25%
760
21%
3171
10%
759
40%
759
18%
1895
December21st to endNight
28%
826
14%
4800
10%
817
43%
817
12%
2882

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
14%5%25%5%35%5%6%8%42%
74661
Night
14%6%25%5%345%5%7%44%
75088
TransparencyDay
39%8%13%23%15%3
74374
Night
39%7%12%22%17%3
74894
SeeingDay
18%13%26%24%14%5%
13830
Night
17%11%29%29%12%1
23514

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
15%5%36%5%35%5%46%43%
1612
11th to 20thDay
16%7%36%43445%7%40%
1638
21st to endDay
15%8%35%6%345%47%40%
1782
February1st to 10thDay
15%7%36%6%45%6%6%6%37%
1620
11th to 20thDay
18%7%345%345%5%6%39%
1595
21st to endDay
18%8%25%5%3435%5%40%
1480
March1st to 10thDay
13%5%25%5%34436%50%
1980
11th to 20thDay
16%6%35%5%35%5%47%42%
1980
21st to endDay
17%7%36%5%4445%7%38%
2186
April1st to 10thDay
12%5%35%5%35%5%5%8%43%
2160
11th to 20thDay
14%5%25%5%3445%6%47%
2134
21st to endDay
19%5%25%5%35%5%5%6%40%
2160
May1st to 10thDay
17%6%245%36%5%5%8%38%
2335
11th to 20thDay
19%5%26%5%45%5%6%8%36%
2362
21st to endDay
15%6%34435%5%6%9%40%
2725
June1st to 10thDay
11%425%5%35%6%7%9%44%
2520
11th to 20thDay
12%5%36%5%35%6%7%9%40%
2520
21st to endDay
9%3246%35%6%7%11%44%
2520
July1st to 10thDay
10%5%26%6%35%6%7%10%42%
2520
11th to 20thDay
6%3245%36%6%8%13%43%
2386
21st to endDay
10%5%35%6%5%7%6%7%10%36%
2547
August1st to 10thDay
9%6%26%7%46%7%7%11%35%
2327
11th to 20thDay
12%425%6%47%6%7%8%38%
2236
21st to endDay
11%425%5%35%5%8%9%42%
2376
September1st to 10thDay
14%5%35%5%34447%45%
2160
11th to 20thDay
13%5%25%43445%7%49%
2154
21st to endDay
20%7%25%4335%5%7%40%
1882
October1st to 10thDay
17%5%245%3445%6%46%
1800
11th to 20thDay
17%4245%34446%48%
1800
21st to endDay
15%5%3443336%5%50%
1980
November1st to 10thDay
13%5%23423448%51%
1804
11th to 20thDay
15%5%3432445%5%51%
1658
21st to endDay
16%42343445%7%47%
1520
December1st to 10thDay
16%7%35%5%35%5%5%7%40%
1520
11th to 20thDay
16%6%25%5%34438%45%
1910
21st to endDay
18%6%25%5%35%5%6%8%36%
2772
January1st to 10thNight
16%6%3443445%7%46%
2552
11th to 20thNight
17%6%35%5%345%5%6%40%
2378
21st to endNight
15%6%35%42445%6%44%
2574
February1st to 10thNight
15%7%35%6%35%5%5%6%39%
2340
11th to 20thNight
18%6%35%5%2445%6%42%
2251
21st to endNight
17%8%36%5%3435%6%41%
1772
March1st to 10thNight
13%434335%5%5%6%49%
1980
11th to 20thNight
17%7%245%23447%43%
1980
21st to endNight
15%6%46%5%3446%7%41%
2170
April1st to 10thNight
14%7%36%5%4445%6%42%
1800
11th to 20thNight
13%6%245%335%5%8%46%
1775
21st to endNight
18%4244345%6%7%44%
1800
May1st to 10thNight
17%5%25%6%35%5%5%9%39%
1639
11th to 20thNight
18%7%35%5%345%5%9%37%
1529
21st to endNight
13%6%245%35%46%10%42%
1550
June1st to 10thNight
10%5%245%35%5%7%8%45%
1440
11th to 20thNight
12%6%35%5%26%5%5%8%43%
1440
21st to endNight
9%425%5%36%5%8%10%44%
1440
July1st to 10thNight
11%5%25%5%35%5%6%10%42%
1440
11th to 20thNight
6%335%6%36%6%6%10%46%
1570
21st to endNight
9%4345%36%6%7%10%42%
1771
August1st to 10thNight
9%425%7%5%7%6%8%9%37%
1611
11th to 20thNight
10%5%36%6%5%6%6%7%8%38%
1647
21st to endNight
10%6%35%5%35%5%7%10%40%
1980
September1st to 10thNight
15%6%25%5%35%5%6%5%45%
1800
11th to 20thNight
10%6%345%33447%50%
1803
21st to endNight
19%6%35%5%34446%42%
2078
October1st to 10thNight
19%6%2443344447%
2160
11th to 20thNight
15%5%24324345%51%
2160
21st to endNight
15%6%23433346%50%
2376
November1st to 10thNight
12%6%245%23345%54%
2273
11th to 20thNight
14%6%24424446%50%
2520
21st to endNight
14%424425%45%7%48%
2660
December1st to 10thNight
17%7%36%43445%6%42%
2660
11th to 20thNight
17%5%25%5%34447%44%
3285
21st to endNight
17%7%35%5%35%5%6%8%37%
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
42%6%9%23%15%4
1613
11th to 20thDay
43%5%12%23%15%2
1638
21st to endDay
44%5%10%24%14%4
1782
February1st to 10thDay
45%8%12%22%11%3
1620
11th to 20thDay
44%6%9%23%16%3
1604
21st to endDay
46%6%11%19%15%4
1480
March1st to 10thDay
37%412%24%20%3
1980
11th to 20thDay
43%6%11%17%17%6%
1980
21st to endDay
46%6%9%19%16%4
2186
April1st to 10thDay
38%6%12%19%19%5%
2160
11th to 20thDay
37%6%11%20%20%6%
2134
21st to endDay
43%7%11%21%14%4
2160
May1st to 10thDay
42%8%14%19%15%2
2335
11th to 20thDay
45%8%13%19%12%2
2366
21st to endDay
39%9%15%25%11%1
2725
June1st to 10thDay
36%9%15%24%15%1
2520
11th to 20thDay
37%11%15%22%13%2
2520
21st to endDay
31%12%16%24%16%1
2520
July1st to 10thDay
36%11%13%22%16%2
2450
11th to 20thDay
30%11%16%26%15%2
2314
21st to endDay
38%10%14%20%16%1
2405
August1st to 10thDay
39%11%16%23%10%1
2314
11th to 20thDay
39%11%14%21%14%1
2236
21st to endDay
35%9%16%23%13%3
2376
September1st to 10thDay
39%7%12%19%18%4
2160
11th to 20thDay
33%6%10%27%20%4
2154
21st to endDay
43%7%10%20%17%2
1882
October1st to 10thDay
38%6%12%25%16%3
1800
11th to 20thDay
37%6%9%24%20%3
1800
21st to endDay
36%49%26%22%3
1980
November1st to 10thDay
33%412%25%21%5%
1804
11th to 20thDay
35%5%12%22%21%6%
1658
21st to endDay
37%6%11%27%17%2
1520
December1st to 10thDay
41%7%12%25%12%3
1520
11th to 20thDay
39%411%31%11%4
1906
21st to endDay
41%9%14%25%10%1
2772
January1st to 10thNight
39%5%10%23%18%5%
2552
11th to 20thNight
43%6%13%21%15%2
2378
21st to endNight
40%411%25%19%2
2574
February1st to 10thNight
43%5%13%23%14%2
2340
11th to 20thNight
42%5%10%21%16%5%
2253
21st to endNight
44%5%10%20%15%5%
1772
March1st to 10thNight
34%7%11%27%18%3
1980
11th to 20thNight
41%5%11%20%18%4
1980
21st to endNight
42%6%12%19%16%6%
2170
April1st to 10thNight
41%7%9%20%19%4
1800
11th to 20thNight
35%7%12%21%19%6%
1775
21st to endNight
39%7%12%25%12%5%
1800
May1st to 10thNight
40%10%13%20%13%4
1639
11th to 20thNight
44%8%13%18%15%2
1530
21st to endNight
37%10%17%23%12%1
1551
June1st to 10thNight
34%9%15%24%17%2
1440
11th to 20thNight
37%10%15%22%14%2
1440
21st to endNight
33%8%17%22%17%3
1440
July1st to 10thNight
38%10%16%20%13%4
1400
11th to 20thNight
30%12%18%22%16%2
1519
21st to endNight
31%10%19%24%15%1
1672
August1st to 10thNight
38%11%15%21%13%1
1600
11th to 20thNight
40%9%15%21%13%2
1647
21st to endNight
37%9%15%23%13%3
1980
September1st to 10thNight
40%8%10%21%17%4
1800
11th to 20thNight
34%5%10%27%21%3
1803
21st to endNight
44%6%10%20%17%3
2078
October1st to 10thNight
39%5%12%23%17%3
2160
11th to 20thNight
35%5%9%27%22%2
2160
21st to endNight
35%5%10%24%22%4
2376
November1st to 10thNight
33%410%25%21%6%
2273
11th to 20thNight
35%5%8%24%22%6%
2520
21st to endNight
35%5%12%24%20%4
2660
December1st to 10thNight
43%5%11%24%14%3
2660
11th to 20thNight
40%5%10%23%17%4
3288
21st to endNight
40%10%16%20%12%1
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
28%27%28%15%2
225
11th to 20thDay
27%26%29%16%1
246
21st to endDay
23%33%30%10%31
264
February1st to 10thDay
21%30%35%10%4
240
11th to 20thDay
35%26%33%5%1
262
21st to endDay
29%23%30%17%1
346
March1st to 10thDay
22%25%30%21%3
420
11th to 20thDay
25%23%30%16%5%2
420
21st to endDay
20%22%34%18%5%1
462
April1st to 10thDay
20%25%27%21%7%1
420
11th to 20thDay
17%18%28%20%14%3
412
21st to endDay
23%16%32%18%10%1
420
May1st to 10thDay
22%18%29%19%9%4
423
11th to 20thDay
21%10%31%21%14%4
447
21st to endDay
20%5%23%25%19%7%
485
June1st to 10thDay
12%7%26%30%20%5%
450
11th to 20thDay
13%8%28%28%16%7%
450
21st to endDay
10%6%28%32%18%6%
450
July1st to 10thDay
12%417%29%26%12%
445
11th to 20thDay
4220%34%30%10%
444
21st to endDay
12%420%32%24%9%
488
August1st to 10thDay
13%419%24%28%12%
446
11th to 20thDay
13%416%32%23%12%
439
21st to endDay
9%318%32%23%14%
495
September1st to 10thDay
17%6%21%24%20%12%
450
11th to 20thDay
14%5%20%30%20%12%
450
21st to endDay
24%11%21%26%15%4
450
October1st to 10thDay
21%6%19%26%20%7%
450
11th to 20thDay
17%14%25%28%14%2
450
21st to endDay
17%11%36%24%10%3
495
November1st to 10thDay
16%13%31%26%10%4
430
11th to 20thDay
19%15%34%21%10%2
318
21st to endDay
19%22%31%20%7%1
180
December1st to 10thDay
17%22%37%19%41
180
11th to 20thDay
22%24%28%21%6%
180
21st to endDay
23%21%31%18%7%1
198
January1st to 10thNight
20%20%39%18%3
760
11th to 20thNight
21%15%33%26%4
732
21st to endNight
18%17%44%20%2
792
February1st to 10thNight
20%16%39%23%3
720
11th to 20thNight
24%21%37%17%2
703
21st to endNight
25%18%37%17%3
592
March1st to 10thNight
18%20%38%22%2
720
11th to 20thNight
23%18%32%21%5%1
720
21st to endNight
19%16%40%20%5%1
792
April1st to 10thNight
17%20%36%22%4
720
11th to 20thNight
17%13%34%28%8%1
711
21st to endNight
20%10%33%29%8%
720
May1st to 10thNight
21%8%27%31%13%1
559
11th to 20thNight
20%5%28%35%11%1
468
21st to endNight
15%321%40%20%1
389
June1st to 10thNight
9%325%41%22%
360
11th to 20thNight
13%323%40%20%1
360
21st to endNight
8%123%49%18%1
360
July1st to 10thNight
12%317%37%27%4
350
11th to 20thNight
7%113%40%36%3
475
21st to endNight
9%316%40%29%4
591
August1st to 10thNight
10%212%42%31%3
537
11th to 20thNight
10%313%40%30%3
583
21st to endNight
11%316%40%26%4
792
September1st to 10thNight
17%218%31%27%4
720
11th to 20thNight
11%418%34%28%3
720
21st to endNight
22%5%22%31%19%1
720
October1st to 10thNight
21%5%22%29%18%4
720
11th to 20thNight
17%11%26%32%13%1
720
21st to endNight
17%12%32%27%12%
792
November1st to 10thNight
14%10%33%30%11%1
740
11th to 20thNight
17%13%33%28%8%1
760
21st to endNight
16%14%33%29%8%1
760
December1st to 10thNight
20%17%35%22%7%
760
11th to 20thNight
18%12%41%24%4
760
21st to endNight
20%14%33%31%3
836
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