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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 2021-04-23.

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
61%
20169
32%
61585
24%
20128
70%
20128
44%
31515

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%
956
36%
2868
22%
956
65%
956
43%
1491
January16th to endNight
51%
1024
38%
3072
24%
1024
65%
1024
45%
1552
February1st to 15thNight
53%
941
37%
2827
22%
936
68%
936
49%
1366
February16th to endNight
42%
844
33%
2530
16%
844
57%
844
45%
1272
March1st to 15thNight
47%
960
33%
2852
17%
960
60%
960
41%
1499
March16th to endNight
49%
868
37%
2660
21%
868
64%
868
47%
1296
April1st to 15thNight
46%
719
37%
2398
22%
719
66%
719
42%
1162
April16th to endNight
51%
693
37%
2307
26%
693
69%
693
49%
1028
May1st to 15thNight
53%
674
29%
2249
25%
674
65%
674
44%
1095
May16th to endNight
65%
705
30%
2212
29%
705
73%
705
45%
1112
June1st to 15thNight
74%
675
26%
2025
25%
675
78%
675
49%
1019
June16th to endNight
78%
675
26%
2025
27%
675
80%
675
44%
1079
July1st to 15thNight
80%
645
19%
2134
22%
645
80%
645
38%
1159
July16th to endNight
83%
708
23%
2251
27%
675
84%
675
39%
1183
August1st to 15thNight
87%
665
26%
2208
32%
662
87%
662
44%
1097
August16th to endNight
81%
717
22%
2390
26%
717
81%
717
31%
1374
September1st to 15thNight
75%
675
21%
2261
24%
675
75%
675
31%
1328
September16th to endNight
75%
672
26%
2475
29%
672
77%
672
32%
1360
October1st to 15thNight
72%
701
31%
2501
31%
701
74%
701
41%
1210
October16th to endNight
70%
960
39%
2880
27%
960
76%
960
54%
1372
November1st to 15thNight
65%
1052
38%
2932
23%
1052
72%
1052
57%
1426
November16th to endNight
62%
1200
40%
3120
21%
1200
70%
1200
56%
1589
December1st to 15thNight
54%
1200
37%
3120
20%
1200
63%
1200
48%
1715
December16th to endNight
48%
1240
39%
3288
19%
1240
61%
1240
48%
1731

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
43133245%5%7%56%
61918
Night
431332445%7%59%
61810
Cloud CoverDay
431342445%7%56%
61916
Night
431332445%7%59%
61810
TransparencyDay
24%5%8%18%24%19%
61638
Night
21%5%9%18%24%19%
61592
SeeingDay
6%8%23%29%24%8%
9873
Night
5%5%21%38%25%2
20179

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%13323347%60%
2390
16th to endDay
3313213435%65%
2560
February1st to 15thDay
2212233446%64%
2350
16th to endDay
2213223447%66%
2110
March1st to 15thDay
332443445%7%55%
2424
16th to endDay
231232435%6%63%
2972
April1st to 15thDay
2312324447%62%
2870
16th to endDay
2313212336%69%
2751
May1st to 15thDay
431222435%7%61%
2691
16th to endDay
411221445%7%64%
2954
June1st to 15thDay
11123235%7%7%62%
2925
16th to endDay
4213435%6%8%9%50%
2925
July1st to 15thDay
8%325%5%5%8%8%7%8%36%
2710
16th to endDay
5%4246%47%8%7%11%37%
2853
August1st to 15thDay
5%3145%47%8%8%12%39%
2654
16th to endDay
7%426%6%47%6%7%9%36%
2868
September1st to 15thDay
12%5%246%47%6%6%7%35%
2688
16th to endDay
9%5%25%5%35%5%6%7%44%
2475
October1st to 15thDay
5%213324346%61%
2445
16th to endDay
421221323470%
2400
November1st to 15thDay
3312313345%67%
2227
16th to endDay
4213212235%70%
2160
December1st to 15thDay
4313314337%62%
2160
16th to endDay
3313213446%64%
2356
January1st to 15thNight
4424314346%60%
2868
16th to endNight
5%213313346%62%
3072
February1st to 15thNight
3313323347%64%
2822
16th to endNight
32123245%47%62%
2530
March1st to 15thNight
441332446%7%57%
2852
16th to endNight
2322313346%63%
2660
April1st to 15thNight
4313313445%62%
2398
16th to endNight
2212223345%68%
2307
May1st to 15thNight
4213323446%61%
2249
16th to endNight
411332445%7%60%
2211
June1st to 15thNight
22134246%8%8%56%
2025
16th to endNight
4213425%6%7%10%51%
2025
July1st to 15thNight
32144346%8%10%48%
2234
16th to endNight
4213325%6%7%11%50%
2371
August1st to 15thNight
22123346%8%16%48%
2219
16th to endNight
4315%5%35%6%8%11%45%
2390
September1st to 15thNight
8%424425%6%7%10%44%
2261
16th to endNight
6%414325%5%7%7%49%
2475
October1st to 15thNight
5%213323447%59%
2501
16th to endNight
421131233470%
2880
November1st to 15thNight
3313213245%69%
2932
16th to endNight
3213312235%69%
3120
December1st to 15thNight
5%213323446%61%
3120
16th to endNight
3313323345%66%
3288

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
4413323346%60%
2390
16th to endDay
3313323436%64%
2560
February1st to 15thDay
2212333446%63%
2350
16th to endDay
2312223447%65%
2110
March1st to 15thDay
342443445%7%54%
2424
16th to endDay
231242445%6%62%
2970
April1st to 15thDay
2313324446%62%
2870
16th to endDay
2312212346%69%
2751
May1st to 15thDay
4313324447%61%
2691
16th to endDay
411222446%7%63%
2954
June1st to 15thDay
11133245%7%7%61%
2925
16th to endDay
4313435%6%7%10%49%
2925
July1st to 15thDay
8%425%5%48%9%6%8%36%
2710
16th to endDay
6%3245%5%8%8%7%10%36%
2853
August1st to 15thDay
5%3145%47%7%8%12%38%
2654
16th to endDay
7%426%7%47%7%6%9%36%
2868
September1st to 15thDay
12%5%25%6%5%6%6%7%7%35%
2688
16th to endDay
10%5%145%35%5%6%7%44%
2475
October1st to 15thDay
6%313423347%60%
2445
16th to endDay
5%3232223470%
2400
November1st to 15thDay
4312312335%67%
2227
16th to endDay
4212312235%70%
2160
December1st to 15thDay
5%323224337%61%
2160
16th to endDay
3413213447%63%
2356
January1st to 15thNight
3424314346%60%
2868
16th to endNight
5%313314346%62%
3072
February1st to 15thNight
3313323347%64%
2822
16th to endNight
331232445%6%62%
2530
March1st to 15thNight
431332446%7%57%
2852
16th to endNight
2313323446%63%
2660
April1st to 15thNight
4313323445%62%
2398
16th to endNight
2312223435%68%
2307
May1st to 15thNight
4313323446%61%
2249
16th to endNight
4113315%45%7%60%
2211
June1st to 15thNight
22134245%7%9%56%
2025
16th to endNight
3213325%6%7%10%51%
2025
July1st to 15thNight
32244346%8%10%48%
2234
16th to endNight
4213425%6%7%11%50%
2371
August1st to 15thNight
32123346%8%16%47%
2219
16th to endNight
43145%35%6%8%12%44%
2390
September1st to 15thNight
8%414435%6%6%10%43%
2261
16th to endNight
7%423325%6%7%8%48%
2475
October1st to 15thNight
5%313323447%59%
2501
16th to endNight
4211212345%69%
2880
November1st to 15thNight
3312212345%68%
2932
16th to endNight
3313312245%69%
3120
December1st to 15thNight
5%213423446%61%
3120
16th to endNight
3312323345%65%
3288

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
24%25%17%30%19%
2391
16th to endDay
20%35%13%34%21%
2560
February1st to 15thDay
19%46%16%24%28%
2351
16th to endDay
18%35%14%30%29%
2110
March1st to 15thDay
25%46%16%25%22%
2424
16th to endDay
19%26%12%28%29%
2972
April1st to 15thDay
19%46%12%28%28%
2870
16th to endDay
15%3410%34%31%
2751
May1st to 15thDay
20%45%13%26%28%
2691
16th to endDay
16%5%7%18%24%27%
2957
June1st to 15thDay
16%5%11%20%27%19%
2925
16th to endDay
24%7%11%20%20%14%
2925
July1st to 15thDay
37%10%13%21%14%2
2581
16th to endDay
33%10%16%27%10%1
2710
August1st to 15thDay
30%10%16%27%13%1
2641
16th to endDay
38%10%16%18%12%3
2868
September1st to 15thDay
41%10%14%17%12%4
2688
16th to endDay
35%6%10%18%19%9%
2475
October1st to 15thDay
20%6%9%23%20%18%
2445
16th to endDay
18%2415%30%29%
2400
November1st to 15thDay
18%47%21%28%20%
2227
16th to endDay
17%25%18%30%26%
2160
December1st to 15thDay
22%35%18%32%18%
2160
16th to endDay
19%35%19%30%21%
2356
January1st to 15thNight
25%2414%29%23%
2868
16th to endNight
22%3413%35%20%
3072
February1st to 15thNight
19%37%14%24%30%
2832
16th to endNight
21%36%10%27%31%
2530
March1st to 15thNight
24%36%15%25%24%
2852
16th to endNight
20%35%13%27%29%
2660
April1st to 15thNight
21%46%12%27%27%
2398
16th to endNight
17%36%14%26%31%
2307
May1st to 15thNight
21%5%6%16%23%27%
2250
16th to endNight
20%6%9%19%21%22%
2213
June1st to 15thNight
18%6%13%24%24%12%
2025
16th to endNight
22%6%14%20%20%14%
2025
July1st to 15thNight
24%9%19%29%14%3
2134
16th to endNight
22%9%19%32%14%1
2251
August1st to 15thNight
19%8%21%32%17%
2208
16th to endNight
29%9%16%25%14%3
2390
September1st to 15thNight
30%10%18%21%13%6%
2261
16th to endNight
29%7%15%19%17%9%
2475
October1st to 15thNight
22%5%12%22%18%19%
2501
16th to endNight
17%35%13%29%30%
2880
November1st to 15thNight
16%36%20%32%20%
2932
16th to endNight
17%2414%32%27%
3120
December1st to 15thNight
23%35%18%30%19%
3120
16th to endNight
21%2417%32%21%
3288

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
6%15%31%33%12%1
270
16th to endDay
6%18%31%29%11%2
288
February1st to 15thDay
6%13%34%25%20%1
270
16th to endDay
6%18%43%22%8%
240
March1st to 15thDay
9%13%44%23%7%1
294
16th to endDay
416%46%22%8%1
544
April1st to 15thDay
417%44%25%7%
509
16th to endDay
5%17%44%25%5%
467
May1st to 15thDay
5%12%34%33%11%2
468
16th to endDay
3432%39%16%2
657
June1st to 15thDay
2113%43%34%4
720
16th to endDay
5%8%36%40%9%
720
July1st to 15thDay
6%327%40%21%
495
16th to endDay
5%226%43%21%
519
August1st to 15thDay
6%219%45%24%
479
16th to endDay
8%1323%42%21%
524
September1st to 15thDay
10%25%32%34%15%
483
16th to endDay
12%111%25%32%16%
270
October1st to 15thDay
9%417%29%29%10%
270
16th to endDay
5%5%26%30%20%11%
288
November1st to 15thDay
8%9%25%30%18%7%
270
16th to endDay
7%15%26%27%15%7%
270
December1st to 15thDay
8%13%28%33%13%1
270
16th to endDay
5%15%37%30%10%
288
January1st to 15thNight
5%5%31%39%15%1
960
16th to endNight
6%8%28%39%15%1
1024
February1st to 15thNight
5%8%30%37%18%1
944
16th to endNight
5%8%40%37%8%
844
March1st to 15thNight
6%9%32%36%14%1
960
16th to endNight
39%32%40%12%1
868
April1st to 15thNight
6%9%34%38%11%
719
16th to endNight
37%34%43%10%
693
May1st to 15thNight
5%5%30%45%12%1
675
16th to endNight
3422%48%20%
707
June1st to 15thNight
3114%52%26%1
675
16th to endNight
417%50%34%2
675
July1st to 15thNight
3434%52%3
645
16th to endNight
3236%51%4
708
August1st to 15thNight
2123%64%8%
665
16th to endNight
5%126%59%6%
717
September1st to 15thNight
8%1326%54%5%
675
16th to endNight
9%16%36%41%5%
672
October1st to 15thNight
6%211%42%32%3
701
16th to endNight
7%316%37%28%7%
960
November1st to 15thNight
6%221%39%26%4
1052
16th to endNight
46%21%39%23%3
1200
December1st to 15thNight
7%5%27%40%17%2
1200
16th to endNight
5%10%31%37%12%2
1240
Page generated at 2021-04-24 10:54:39. Version ac04

Copyright 2021 A. Danko


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