McKinney
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the McKinney clear sky chart from 2005-11-05 to 2017-08-12.

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
51%
15489
29%
46536
21%
15445
60%
15445
40%
25388

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
39%
897
31%
2327
13%
895
50%
895
40%
1363
January16th to endNight
39%
960
34%
2496
13%
960
51%
960
42%
1435
February1st to 15thNight
33%
779
27%
2187
10%
775
45%
775
35%
1284
February16th to endNight
27%
609
31%
1871
11%
609
43%
609
34%
1036
March1st to 15thNight
33%
540
28%
1980
16%
540
48%
540
27%
1101
March16th to endNight
39%
576
24%
2112
18%
576
51%
576
29%
1160
April1st to 15thNight
35%
539
25%
1962
14%
539
52%
539
31%
1030
April16th to endNight
39%
540
26%
1719
19%
540
53%
540
35%
949
May1st to 15thNight
39%
540
24%
1620
14%
540
53%
540
34%
947
May16th to endNight
55%
563
27%
1684
23%
561
64%
561
40%
930
June1st to 15thNight
71%
540
24%
1620
25%
540
76%
540
52%
803
June16th to endNight
76%
540
26%
1620
29%
540
79%
540
49%
830
July1st to 15thNight
82%
510
23%
1530
27%
510
83%
510
46%
799
July16th to endNight
89%
564
32%
1594
39%
531
90%
531
58%
742
August1st to 15thNight
90%
527
38%
1575
45%
524
91%
524
62%
706
August16th to endNight
80%
525
30%
1712
35%
525
81%
525
41%
901
September1st to 15thNight
70%
495
24%
1815
28%
495
71%
495
33%
966
September16th to endNight
75%
492
34%
1815
38%
492
78%
492
42%
870
October1st to 15thNight
62%
577
35%
1897
29%
577
67%
577
42%
963
October16th to endNight
52%
704
37%
2112
21%
704
63%
704
49%
1052
November1st to 15thNight
53%
712
33%
2112
20%
712
62%
712
43%
1122
November16th to endNight
43%
900
33%
2340
17%
900
52%
900
40%
1379
December1st to 15thNight
38%
900
30%
2340
14%
900
48%
900
35%
1457
December16th to endNight
35%
960
28%
2496
12%
960
45%
960
35%
1563

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
11%42442445%7%51%
47434
Night
9%313323346%56%
46732
TransparencyDay
32%410%24%22%6%
47134
Night
28%39%23%24%10%
46537
SeeingDay
10%317%27%29%11%
5470
Night
11%5%26%34%19%2
15492

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 15thDay
13%6%23212235%56%
1611
16th to endDay
14%312323335%54%
1728
February1st to 15thDay
15%5%24322335%52%
1684
16th to endDay
16%5%23311335%53%
1601
March1st to 15thDay
18%5%24323246%45%
1980
16th to endDay
15%5%35%42333448%
2110
April1st to 15thDay
12%5%13324347%50%
1986
16th to endDay
13%414323446%48%
2238
May1st to 15thDay
14%5%35%5%3435%6%43%
2331
16th to endDay
10%5%25%5%36%5%6%7%40%
2430
June1st to 15thDay
5%3145%25%5%5%9%51%
2340
16th to endDay
5%323425%46%8%52%
2340
July1st to 15thDay
6%323436%6%7%8%45%
2340
16th to endDay
42135%35%5%7%10%51%
2466
August1st to 15thDay
3212325%5%6%8%59%
2289
16th to endDay
6%3145%47%6%7%9%42%
2135
September1st to 15thDay
12%415%42345%8%46%
1815
16th to endDay
7%413423447%55%
1815
October1st to 15thDay
11%313322345%58%
1722
16th to endDay
8%31221223466%
1760
November1st to 15thDay
8%413325%34457%
1745
16th to endDay
13%413212225%59%
1620
December1st to 15thDay
17%6%14312335%49%
1620
16th to endDay
17%5%24312346%49%
1728
January1st to 15thNight
11%313322335%58%
2327
16th to endNight
11%413222345%59%
2496
February1st to 15thNight
12%42431333456%
2177
16th to endNight
14%41322233457%
1871
March1st to 15thNight
15%42431345%5%49%
1980
16th to endNight
12%424323445%53%
2112
April1st to 15thNight
9%42332345%6%54%
1962
16th to endNight
11%423323445%54%
1719
May1st to 15thNight
9%5%24424447%51%
1619
16th to endNight
6%41332346%11%51%
1683
June1st to 15thNight
3213313449%62%
1620
16th to endNight
321332345%10%59%
1620
July1st to 15thNight
42133235%7%12%52%
1620
16th to endNight
21221345%10%63%
1702
August1st to 15thNight
11121335%8%68%
1585
16th to endNight
4313325%5%6%12%51%
1712
September1st to 15thNight
10%42332235%7%51%
1815
16th to endNight
6%31332335%8%59%
1815
October1st to 15thNight
10%312312335%61%
1897
16th to endNight
9%21221122368%
2112
November1st to 15thNight
7%31432233462%
2112
16th to endNight
12%31421334457%
2340
December1st to 15thNight
14%423314236%52%
2340
16th to endNight
14%6%24313336%50%
2496

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
31%27%21%30%6%
1612
16th to endDay
32%26%21%28%8%
1728
February1st to 15thDay
37%25%23%23%7%
1685
16th to endDay
35%26%23%21%11%
1601
March1st to 15thDay
41%36%19%20%9%
1980
16th to endDay
39%310%18%21%6%
2112
April1st to 15thDay
34%310%22%18%10%
1986
16th to endDay
35%49%20%23%6%
2238
May1st to 15thDay
41%38%18%19%7%
2331
16th to endDay
39%5%11%23%17%2
2434
June1st to 15thDay
28%5%13%28%20%2
2340
16th to endDay
27%5%12%28%21%4
2340
July1st to 15thDay
28%6%14%33%15%1
2201
16th to endDay
23%6%19%32%16%1
2311
August1st to 15thDay
18%6%14%33%24%3
2275
16th to endDay
32%5%14%30%13%2
2135
September1st to 15thDay
34%411%24%17%8%
1815
16th to endDay
26%47%23%27%9%
1815
October1st to 15thDay
28%39%22%20%14%
1722
16th to endDay
23%26%20%31%15%
1760
November1st to 15thDay
30%27%25%24%8%
1745
16th to endDay
30%2418%32%12%
1620
December1st to 15thDay
39%25%20%26%4
1620
16th to endDay
37%26%22%22%7%
1728
January1st to 15thNight
30%26%18%31%11%
2327
16th to endNight
28%25%21%29%12%
2496
February1st to 15thNight
33%26%20%23%12%
2187
16th to endNight
31%27%22%21%13%
1871
March1st to 15thNight
36%28%18%22%11%
1980
16th to endNight
33%410%21%24%5%
2112
April1st to 15thNight
29%410%22%18%14%
1962
16th to endNight
31%310%20%23%9%
1719
May1st to 15thNight
33%412%18%22%9%
1620
16th to endNight
27%5%17%27%19%3
1685
June1st to 15thNight
18%5%13%34%23%5%
1620
16th to endNight
20%5%12%29%25%6%
1620
July1st to 15thNight
22%5%13%36%18%3
1530
16th to endNight
14%417%36%23%2
1594
August1st to 15thNight
13%212%33%30%7%
1575
16th to endNight
25%5%11%34%18%4
1712
September1st to 15thNight
31%411%21%20%10%
1815
16th to endNight
23%37%24%27%12%
1815
October1st to 15thNight
26%29%23%22%16%
1897
16th to endNight
22%1418%30%21%
2112
November1st to 15thNight
26%26%26%24%13%
2112
16th to endNight
30%26%14%32%13%
2340
December1st to 15thNight
35%27%21%24%8%
2340
16th to endNight
36%27%21%22%9%
2496

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
12%13%28%32%12%1
90
16th to endDay
13%6%42%23%12%1
96
February1st to 15thDay
8%6%44%30%10%
90
16th to endDay
13%448%25%7%
81
March1st to 15thDay
23%10%35%24%5%1
90
16th to endDay
7%5%41%28%13%4
96
April1st to 15thDay
12%10%27%34%15%
105
16th to endDay
18%8%34%25%11%2
348
May1st to 15thDay
17%7%33%27%10%3
468
16th to endDay
14%328%30%19%3
517
June1st to 15thDay
6%210%38%32%10%
495
16th to endDay
7%210%31%33%15%
495
July1st to 15thDay
5%15%33%40%13%
475
16th to endDay
2315%51%26%
515
August1st to 15thDay
4222%50%19%
474
16th to endDay
12%227%42%13%
303
September1st to 15thDay
3111%44%40%
90
16th to endDay
5%15%43%35%
90
October1st to 15thDay
12%31%44%12%
90
16th to endDay
13%111%33%35%5%
96
November1st to 15thDay
26%218%28%16%6%
90
16th to endDay
26%11%31%20%7%3
90
December1st to 15thDay
28%422%27%13%3
90
16th to endDay
11%11%44%26%6%
96
January1st to 15thNight
13%10%32%35%8%
900
16th to endNight
13%8%36%34%6%
960
February1st to 15thNight
15%9%37%31%6%
779
16th to endNight
15%10%44%25%3
609
March1st to 15thNight
17%9%35%31%6%
540
16th to endNight
13%8%36%31%9%
576
April1st to 15thNight
10%7%43%31%6%
539
16th to endNight
12%7%37%30%11%
540
May1st to 15thNight
10%6%37%33%9%2
540
16th to endNight
7%228%37%20%1
563
June1st to 15thNight
3115%45%30%3
540
16th to endNight
3111%45%34%4
540
July1st to 15thNight
5%5%42%41%4
510
16th to endNight
21132%53%8%
564
August1st to 15thNight
2234%52%8%
527
16th to endNight
6%435%47%5%
525
September1st to 15thNight
12%6%34%41%3
495
16th to endNight
7%18%38%39%5%
492
October1st to 15thNight
10%120%37%24%4
577
16th to endNight
10%5%28%34%18%1
704
November1st to 15thNight
8%5%28%37%18%1
712
16th to endNight
14%8%31%32%11%1
900
December1st to 15thNight
17%7%32%34%7%
900
16th to endNight
17%7%36%31%6%
960
Page generated at 2017-08-13 13:16:51. Version ac04

Copyright 2017 A. Danko


McKinney Clear Sky Chart | Charts Home