This page made possible by the sponsorship of:
.

Texas Star Party
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Texas Star Party clear sky chart from 2005-11-05 to 2018-03-21.

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
62%
16167
32%
49300
23%
16126
71%
16126
44%
25278

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 15thNight
51%
776
36%
2328
21%
776
65%
776
43%
1216
January16th to endNight
53%
832
39%
2496
25%
832
66%
832
45%
1260
February1st to 15thNight
56%
761
37%
2287
22%
756
70%
756
51%
1098
February16th to endNight
44%
684
35%
2050
18%
684
59%
684
48%
996
March1st to 15thNight
52%
780
33%
2317
19%
780
63%
780
45%
1170
March16th to endNight
50%
675
38%
2061
22%
675
65%
675
48%
996
April1st to 15thNight
47%
539
34%
1798
21%
539
65%
539
42%
865
April16th to endNight
51%
540
36%
1800
27%
540
69%
540
50%
790
May1st to 15thNight
50%
539
28%
1799
22%
539
64%
539
43%
875
May16th to endNight
62%
561
26%
1760
24%
561
70%
561
40%
934
June1st to 15thNight
74%
540
25%
1620
23%
540
79%
540
49%
808
June16th to endNight
77%
540
25%
1620
25%
540
79%
540
43%
871
July1st to 15thNight
78%
510
19%
1688
23%
510
78%
510
37%
928
July16th to endNight
81%
564
22%
1771
26%
531
81%
531
35%
979
August1st to 15thNight
84%
539
23%
1789
30%
536
85%
536
41%
920
August16th to endNight
79%
573
21%
1910
24%
573
80%
573
29%
1141
September1st to 15thNight
76%
540
20%
1809
23%
540
76%
540
31%
1053
September16th to endNight
75%
537
26%
1980
28%
537
76%
537
30%
1122
October1st to 15thNight
73%
561
32%
2001
33%
561
75%
561
42%
961
October16th to endNight
72%
768
39%
2304
28%
768
78%
768
57%
1073
November1st to 15thNight
67%
851
37%
2371
23%
851
73%
851
60%
1119
November16th to endNight
63%
975
41%
2535
23%
975
71%
975
56%
1284
December1st to 15thNight
56%
975
36%
2535
20%
975
65%
975
48%
1410
December16th to endNight
49%
1007
39%
2671
20%
1007
61%
1007
48%
1409

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
5%31332445%7%56%
49509
Night
431332445%7%59%
49525
Cloud CoverDay
5%3134245%5%7%55%
49507
Night
431332445%7%59%
49525
TransparencyDay
24%5%8%17%24%18%
49229
Night
21%5%9%18%25%19%
49307
SeeingDay
6%7%21%30%25%8%
5808
Night
5%5%20%37%27%3
16177

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 15thDay
45%13323337%60%
1940
16th to endDay
4313223435%64%
2080
February1st to 15thDay
22122245%45%66%
1900
16th to endDay
121321335%7%68%
1710
March1st to 15thDay
232443445%7%57%
1969
16th to endDay
2312323346%65%
2290
April1st to 15thDay
232232445%6%63%
2150
16th to endDay
222212336%71%
2160
May1st to 15thDay
3312224346%64%
2151
16th to endDay
5%2122245%5%8%61%
2351
June1st to 15thDay
11123236%7%7%62%
2340
16th to endDay
5%313435%6%8%9%47%
2340
July1st to 15thDay
10%325%447%8%6%8%36%
2167
16th to endDay
7%5%246%5%8%8%6%10%33%
2277
August1st to 15thDay
6%3145%47%8%8%11%36%
2160
16th to endDay
8%5%36%7%48%6%6%9%33%
2292
September1st to 15thDay
13%5%25%6%47%5%6%7%34%
2150
16th to endDay
10%6%15%6%345%6%6%44%
1980
October1st to 15thDay
6%214314346%61%
1956
16th to endDay
422213235%71%
1920
November1st to 15thDay
3312312345%68%
1802
16th to endDay
42321213471%
1755
December1st to 15thDay
5%313314347%61%
1755
16th to endDay
3413213447%62%
1914
January1st to 15thNight
4424324336%60%
2328
16th to endNight
5%223314346%62%
2496
February1st to 15thNight
2313323346%65%
2282
16th to endNight
2222245%46%65%
2050
March1st to 15thNight
331332345%7%61%
2317
16th to endNight
2323313345%65%
2061
April1st to 15thNight
4213414446%63%
1798
16th to endNight
221222333470%
1800
May1st to 15thNight
42133235%46%62%
1799
16th to endNight
5%113325%46%8%55%
1759
June1st to 15thNight
21124246%7%8%57%
1620
16th to endNight
4213435%6%8%10%50%
1620
July1st to 15thNight
4214435%6%7%10%48%
1788
16th to endNight
4224425%6%7%12%45%
1891
August1st to 15thNight
3312435%6%8%16%45%
1800
16th to endNight
5%3145%36%6%8%11%43%
1910
September1st to 15thNight
8%413425%6%7%10%44%
1809
16th to endNight
7%424325%6%8%8%45%
1980
October1st to 15thNight
6%313322447%60%
2001
16th to endNight
32121234471%
2304
November1st to 15thNight
222213245%71%
2371
16th to endNight
321331223471%
2535
December1st to 15thNight
4213433446%60%
2535
16th to endNight
3413223335%66%
2671

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 15thDay
4423424337%60%
1940
16th to endDay
3312323436%64%
2080
February1st to 15thDay
22123235%45%66%
1900
16th to endDay
1212223347%67%
1710
March1st to 15thDay
232442445%6%56%
1969
16th to endDay
2312324346%64%
2288
April1st to 15thDay
2312324446%63%
2150
16th to endDay
232212346%71%
2160
May1st to 15thDay
3212314446%63%
2151
16th to endDay
5%21222446%7%60%
2351
June1st to 15thDay
11133246%7%8%60%
2340
16th to endDay
5%3235%35%6%7%10%47%
2340
July1st to 15thDay
9%4245%47%9%6%8%35%
2167
16th to endDay
6%425%6%5%9%7%7%10%32%
2277
August1st to 15thDay
6%3146%37%8%9%12%35%
2160
16th to endDay
8%5%27%7%5%7%7%5%8%33%
2292
September1st to 15thDay
13%6%25%6%46%6%7%6%34%
2150
16th to endDay
11%6%15%6%35%5%6%6%42%
1980
October1st to 15thDay
6%313323347%60%
1956
16th to endDay
422222235%70%
1920
November1st to 15thDay
4312212335%67%
1802
16th to endDay
4312212135%70%
1755
December1st to 15thDay
5%323324337%61%
1755
16th to endDay
3413213447%62%
1914
January1st to 15thNight
45%24314336%60%
2328
16th to endNight
5%323314346%62%
2496
February1st to 15thNight
2213223447%64%
2282
16th to endNight
22232345%7%65%
2050
March1st to 15thNight
431332445%6%60%
2317
16th to endNight
2313323345%65%
2061
April1st to 15thNight
4313323436%63%
1798
16th to endNight
221222333470%
1800
May1st to 15thNight
3314323446%62%
1799
16th to endNight
5%113416%46%8%55%
1759
June1st to 15thNight
21134246%7%9%56%
1620
16th to endNight
4213326%6%8%10%50%
1620
July1st to 15thNight
4323435%6%7%10%47%
1788
16th to endNight
4314436%6%7%12%45%
1891
August1st to 15thNight
32133346%8%16%44%
1800
16th to endNight
43145%36%6%8%12%42%
1910
September1st to 15thNight
8%414425%6%6%11%43%
1809
16th to endNight
8%424325%6%8%9%44%
1980
October1st to 15thNight
6%213323347%60%
2001
16th to endNight
221121234471%
2304
November1st to 15thNight
3212212345%70%
2371
16th to endNight
321231223470%
2535
December1st to 15thNight
4213424446%59%
2535
16th to endNight
3412323345%65%
2671

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 15thDay
25%25%18%31%16%
1941
16th to endDay
20%35%14%34%21%
2080
February1st to 15thDay
16%46%15%26%29%
1901
16th to endDay
15%25%15%32%27%
1710
March1st to 15thDay
23%45%16%25%24%
1969
16th to endDay
19%25%12%30%29%
2290
April1st to 15thDay
20%46%9%29%30%
2150
16th to endDay
14%249%34%34%
2160
May1st to 15thDay
19%45%12%25%31%
2151
16th to endDay
18%5%8%17%23%25%
2354
June1st to 15thDay
15%5%11%20%26%20%
2340
16th to endDay
27%7%12%20%20%11%
2340
July1st to 15thDay
37%9%13%22%14%1
2038
16th to endDay
37%11%16%25%8%1
2134
August1st to 15thDay
33%10%17%25%12%1
2147
16th to endDay
42%10%15%17%11%2
2292
September1st to 15thDay
41%10%13%18%12%3
2150
16th to endDay
36%6%10%19%19%7%
1980
October1st to 15thDay
21%6%9%23%20%18%
1956
16th to endDay
16%2416%30%29%
1920
November1st to 15thDay
17%37%21%28%21%
1802
16th to endDay
17%25%17%32%25%
1755
December1st to 15thDay
22%35%18%32%17%
1755
16th to endDay
20%45%21%31%16%
1914
January1st to 15thNight
25%25%15%31%19%
2328
16th to endNight
22%3414%34%20%
2496
February1st to 15thNight
18%36%12%26%32%
2292
16th to endNight
19%36%10%31%29%
2050
March1st to 15thNight
21%35%16%26%26%
2317
16th to endNight
20%35%14%28%29%
2061
April1st to 15thNight
22%36%11%28%27%
1798
16th to endNight
16%35%12%25%35%
1800
May1st to 15thNight
21%45%15%21%30%
1800
16th to endNight
23%7%9%17%18%22%
1761
June1st to 15thNight
17%7%14%23%24%12%
1620
16th to endNight
23%7%16%20%19%12%
1620
July1st to 15thNight
25%9%17%30%15%2
1688
16th to endNight
25%10%19%30%12%1
1771
August1st to 15thNight
21%8%23%28%17%
1789
16th to endNight
31%11%16%25%12%2
1910
September1st to 15thNight
29%10%19%23%12%5%
1809
16th to endNight
31%7%15%21%17%6%
1980
October1st to 15thNight
21%5%12%24%18%17%
2001
16th to endNight
15%36%14%28%31%
2304
November1st to 15thNight
14%35%20%33%21%
2371
16th to endNight
17%2413%32%29%
2535
December1st to 15thNight
23%35%19%28%18%
2535
16th to endNight
21%2419%33%18%
2671

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 15thDay
5%18%25%34%14%
135
16th to endDay
6%18%26%29%12%5%
144
February1st to 15thDay
27%28%29%29%1
135
16th to endDay
5%17%38%25%11%1
120
March1st to 15thDay
27%46%31%10%2
154
16th to endDay
316%45%22%9%2
311
April1st to 15thDay
418%44%22%9%
269
16th to endDay
221%42%25%6%1
270
May1st to 15thDay
315%40%33%6%
288
16th to endDay
5%435%36%15%2
438
June1st to 15thDay
1112%43%34%6%
495
16th to endDay
5%16%35%41%9%
495
July1st to 15thDay
8%332%36%17%
312
16th to endDay
7%1428%40%18%
327
August1st to 15thDay
8%219%45%22%
315
16th to endDay
11%1426%37%17%
332
September1st to 15thDay
9%26%31%35%15%
305
16th to endDay
15%212%30%30%8%
135
October1st to 15thDay
15%214%31%25%11%
135
16th to endDay
3224%26%27%16%
144
November1st to 15thDay
10%6%23%29%20%8%
135
16th to endDay
8%11%25%29%16%8%
135
December1st to 15thDay
11%5%27%40%14%1
135
16th to endDay
6%14%35%30%12%
144
January1st to 15thNight
6%5%30%37%17%2
780
16th to endNight
5%9%27%38%17%1
832
February1st to 15thNight
37%29%36%21%1
764
16th to endNight
48%38%37%10%
684
March1st to 15thNight
5%8%28%38%17%1
780
16th to endNight
39%31%38%15%1
675
April1st to 15thNight
5%9%33%39%10%
539
16th to endNight
37%33%43%11%
540
May1st to 15thNight
5%5%33%42%12%1
540
16th to endNight
4424%46%20%
563
June1st to 15thNight
215%52%27%1
540
16th to endNight
5%17%47%36%2
540
July1st to 15thNight
45%37%49%3
510
16th to endNight
4234%52%4
564
August1st to 15thNight
220%65%9%
539
16th to endNight
5%125%60%6%
573
September1st to 15thNight
8%1224%55%7%
540
16th to endNight
9%15%37%40%5%
537
October1st to 15thNight
7%111%41%34%3
561
16th to endNight
5%215%35%31%9%
768
November1st to 15thNight
5%220%36%30%5%
851
16th to endNight
5%6%19%38%26%4
975
December1st to 15thNight
6%5%25%40%18%2
975
16th to endNight
5%10%29%37%14%2
1007
Page generated at 2018-03-22 10:34:25. Version ac04

Copyright 2018 A. Danko


Texas Star Party Clear Sky Chart |Charts Home