Prairie Grass Stargaze
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Prairie Grass Stargaze clear sky chart from 2005-11-05 to 2017-03-22.

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
35%
15568
17%
44998
9%
15521
42%
15521
25%
29718

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
24%
900
14%
2455
5%
895
31%
895
20%
1770
January16th to endNight
21%
960
13%
2496
4%
960
29%
960
17%
1899
February1st to 15thNight
25%
879
11%
2288
3%
875
30%
875
20%
1695
February16th to endNight
26%
753
15%
2015
5%
753
34%
753
22%
1418
March1st to 15thNight
30%
551
17%
1991
9%
551
40%
551
20%
1285
March16th to endNight
30%
549
13%
2013
10%
549
36%
549
15%
1393
April1st to 15thNight
29%
494
17%
1673
11%
494
39%
494
22%
1073
April16th to endNight
27%
495
17%
1485
10%
495
37%
495
20%
1055
May1st to 15thNight
30%
495
15%
1459
9%
495
36%
495
25%
984
May16th to endNight
40%
515
14%
1370
6%
513
44%
513
28%
921
June1st to 15thNight
48%
495
14%
1283
5%
495
51%
495
33%
837
June16th to endNight
57%
495
19%
1155
6%
495
60%
495
48%
693
July1st to 15thNight
60%
465
20%
1120
8%
465
63%
465
53%
637
July16th to endNight
67%
522
21%
1419
15%
489
69%
489
49%
731
August1st to 15thNight
63%
494
24%
1475
21%
491
68%
491
42%
805
August16th to endNight
60%
525
23%
1602
23%
525
66%
525
41%
866
September1st to 15thNight
55%
495
25%
1686
23%
495
64%
495
36%
896
September16th to endNight
43%
492
25%
1815
16%
492
57%
492
32%
970
October1st to 15thNight
35%
654
25%
1974
14%
654
44%
654
31%
1178
October16th to endNight
34%
705
18%
2113
9%
705
41%
705
25%
1357
November1st to 15thNight
30%
875
22%
2383
9%
875
40%
875
28%
1544
November16th to endNight
28%
900
17%
2520
8%
900
35%
900
22%
1735
December1st to 15thNight
21%
900
10%
2520
3%
900
28%
900
16%
1878
December16th to endNight
21%
960
14%
2688
4%
960
30%
960
14%
2098

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
13%7%35%5%3445%7%38%
45885
Night
11%7%36%5%24446%42%
45171
Cloud CoverDay
13%7%36%5%3445%7%38%
45896
Night
11%7%36%5%34446%42%
45175
Cloud CoverDay
13%7%36%5%3445%7%38%
45894
Night
11%7%36%424446%42%
45175
TransparencyDay
44%6%14%22%10%1
45576
Night
41%6%14%23%13%1
44998
SeeingDay
16%8%30%27%14%3
5277
Night
15%9%34%29%10%
15569

By Month

Percentage Cloud Cover NE (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
7%11%7%9%8%346%7%6%27%
1482
16th to endDay
8%13%7%9%9%36%5%5%6%24%
1728
February1st to 15thDay
9%11%5%9%9%46%5%5%6%26%
1575
16th to endDay
11%9%48%8%36%5%6%6%30%
1470
March1st to 15thDay
16%9%6%8%5%24445%31%
1957
16th to endDay
15%10%6%7%5%245%5%7%30%
2007
April1st to 15thDay
17%7%35%5%3445%7%35%
1941
16th to endDay
25%10%35%42444430%
2145
May1st to 15thDay
22%8%35%5%34446%31%
2161
16th to endDay
14%5%25%5%345%6%8%36%
2393
June1st to 15thDay
17%6%25%5%35%45%7%36%
2343
16th to endDay
9%42343446%10%47%
2475
July1st to 15thDay
6%3144245%6%9%52%
2434
16th to endDay
5%3135%25%5%6%9%52%
2331
August1st to 15thDay
8%435%6%35%6%6%8%40%
2145
16th to endDay
10%41443446%8%48%
2248
September1st to 15thDay
11%5%23435%45%6%47%
1942
16th to endDay
12%423433347%50%
1810
October1st to 15thDay
14%6%34424345%47%
1650
16th to endDay
16%7%25%5%33335%43%
1757
November1st to 15thDay
11%8%36%32335%6%46%
1475
16th to endDay
12%10%28%6%3435%8%34%
1440
December1st to 15thDay
15%11%49%9%44445%26%
1440
16th to endDay
16%11%6%8%8%34246%24%
1536
January1st to 15thNight
8%7%5%8%7%46%6%5%7%31%
2455
16th to endNight
8%12%5%9%7%45%5%5%7%26%
2496
February1st to 15thNight
10%11%49%6%34446%33%
2285
16th to endNight
8%7%48%7%35%46%7%35%
2015
March1st to 15thNight
11%8%46%5%23447%40%
1979
16th to endNight
16%8%45%6%24446%35%
2013
April1st to 15thNight
15%8%25%423446%41%
1673
16th to endNight
20%9%35%424335%36%
1485
May1st to 15thNight
16%6%34424336%42%
1459
16th to endNight
12%425%5%25%47%8%40%
1368
June1st to 15thNight
10%5%23415%5%5%9%45%
1283
16th to endNight
5%3132145%6%8%58%
1155
July1st to 15thNight
32132145%5%7%62%
1193
16th to endNight
221232446%9%60%
1526
August1st to 15thNight
5%31342445%8%56%
1485
16th to endNight
8%323313336%59%
1602
September1st to 15thNight
9%323323346%56%
1686
16th to endNight
10%423223447%54%
1815
October1st to 15thNight
14%5%24313345%51%
1974
16th to endNight
17%7%34412345%44%
2113
November1st to 15thNight
10%6%36%5%34345%47%
2383
16th to endNight
12%8%36%5%35%445%40%
2520
December1st to 15thNight
12%10%5%8%7%46%445%30%
2520
16th to endNight
16%12%5%8%6%35%5%45%26%
2688

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
7%11%7%9%8%445%7%6%27%
1482
16th to endDay
8%13%7%9%8%45%6%5%6%24%
1728
February1st to 15thDay
9%11%5%9%9%46%5%5%6%26%
1575
16th to endDay
11%9%47%8%36%6%6%6%29%
1470
March1st to 15thDay
16%10%6%8%5%2445%5%30%
1968
16th to endDay
15%10%6%7%5%2445%7%30%
2007
April1st to 15thDay
17%7%36%5%3435%7%35%
1941
16th to endDay
25%9%35%43444430%
2145
May1st to 15thDay
22%7%35%5%35%446%31%
2161
16th to endDay
14%5%36%5%35%5%6%8%36%
2393
June1st to 15thDay
17%6%25%5%3445%8%36%
2343
16th to endDay
9%41343446%10%47%
2475
July1st to 15thDay
5%3134345%5%9%52%
2434
16th to endDay
5%314425%5%5%9%52%
2331
August1st to 15thDay
7%5%35%6%45%6%6%7%40%
2145
16th to endDay
10%42343445%8%48%
2248
September1st to 15thDay
11%423435%45%6%47%
1942
16th to endDay
12%5%13423347%50%
1810
October1st to 15thDay
14%6%24324335%47%
1650
16th to endDay
15%7%25%5%23345%43%
1757
November1st to 15thDay
11%7%36%42325%6%46%
1475
16th to endDay
12%10%27%6%2435%7%35%
1440
December1st to 15thDay
15%12%49%9%44445%25%
1440
16th to endDay
16%12%6%8%9%25%246%24%
1536
January1st to 15thNight
8%7%5%8%7%47%5%6%7%31%
2455
16th to endNight
8%12%6%9%7%36%5%5%7%26%
2496
February1st to 15thNight
10%12%49%6%345%46%33%
2278
16th to endNight
8%6%48%6%45%46%7%35%
2015
March1st to 15thNight
11%9%47%43335%6%40%
1991
16th to endNight
16%9%45%6%24445%35%
2013
April1st to 15thNight
15%7%25%4235%46%41%
1673
16th to endNight
20%10%35%424335%37%
1485
May1st to 15thNight
16%6%25%434345%42%
1458
16th to endNight
11%425%5%25%46%8%41%
1368
June1st to 15thNight
11%423425%5%6%8%45%
1283
16th to endNight
5%2122235%6%8%59%
1155
July1st to 15thNight
311321345%7%62%
1193
16th to endNight
221232446%9%59%
1526
August1st to 15thNight
5%31432445%8%56%
1485
16th to endNight
8%222313346%59%
1602
September1st to 15thNight
9%414323337%55%
1686
16th to endNight
9%42331345%7%53%
1815
October1st to 15thNight
13%6%24322335%51%
1974
16th to endNight
17%7%25%312346%44%
2113
November1st to 15thNight
10%6%36%5%33435%47%
2383
16th to endNight
12%8%36%5%35%445%40%
2520
December1st to 15thNight
12%11%48%7%45%445%30%
2520
16th to endNight
16%12%5%8%6%35%445%26%
2688

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
7%11%7%9%8%445%6%6%27%
1482
16th to endDay
8%13%7%9%8%45%6%5%5%25%
1728
February1st to 15thDay
9%12%49%9%46%45%6%26%
1575
16th to endDay
11%9%47%7%36%5%7%6%29%
1470
March1st to 15thDay
16%10%6%8%5%2435%6%31%
1968
16th to endDay
15%11%5%7%5%2445%6%30%
2005
April1st to 15thDay
17%7%36%43445%7%36%
1941
16th to endDay
25%10%36%42434430%
2145
May1st to 15thDay
23%7%345%3445%6%31%
2161
16th to endDay
14%6%26%5%35%5%6%8%37%
2393
June1st to 15thDay
18%5%35%43445%8%36%
2343
16th to endDay
10%3144245%6%9%47%
2475
July1st to 15thDay
6%31342346%9%52%
2434
16th to endDay
5%3243245%6%9%52%
2331
August1st to 15thDay
8%5%35%6%36%6%6%7%42%
2145
16th to endDay
11%32442435%8%48%
2248
September1st to 15thDay
11%5%13425%446%48%
1942
16th to endDay
12%5%13413347%50%
1810
October1st to 15thDay
14%6%24324345%47%
1650
16th to endDay
16%6%25%423336%43%
1757
November1st to 15thDay
11%7%36%32235%7%45%
1475
16th to endDay
13%9%36%6%3435%7%35%
1440
December1st to 15thDay
15%11%5%7%10%44345%26%
1440
16th to endDay
16%13%6%8%7%34335%25%
1536
January1st to 15thNight
8%7%5%8%7%47%5%6%6%32%
2455
16th to endNight
9%11%5%10%6%45%6%5%7%27%
2496
February1st to 15thNight
10%12%5%8%6%35%446%33%
2278
16th to endNight
9%6%47%6%45%5%5%7%36%
2015
March1st to 15thNight
12%8%46%5%23446%40%
1991
16th to endNight
16%9%46%6%24445%35%
2013
April1st to 15thNight
16%7%25%41445%5%42%
1673
16th to endNight
21%8%3442333437%
1485
May1st to 15thNight
17%5%24425%346%42%
1458
16th to endNight
12%5%25%425%5%6%8%41%
1368
June1st to 15thNight
10%5%13425%5%6%8%45%
1283
16th to endNight
5%2122135%6%7%59%
1155
July1st to 15thNight
321322435%8%62%
1193
16th to endNight
321222445%9%60%
1526
August1st to 15thNight
6%31432345%8%56%
1485
16th to endNight
8%313313246%60%
1602
September1st to 15thNight
9%313324337%56%
1686
16th to endNight
10%32332445%7%53%
1815
October1st to 15thNight
13%6%24413335%52%
1974
16th to endNight
16%8%25%312346%44%
2113
November1st to 15thNight
10%6%26%5%33435%47%
2383
16th to endNight
12%8%36%435%436%40%
2520
December1st to 15thNight
13%10%48%8%35%445%30%
2520
16th to endNight
16%12%5%8%5%345%45%26%
2688

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
53%7%14%16%8%
1483
16th to endDay
59%6%14%15%4
1728
February1st to 15thDay
56%5%15%15%5%
1576
16th to endDay
52%8%12%17%8%1
1470
March1st to 15thDay
53%5%14%19%5%
1968
16th to endDay
53%7%14%20%4
2007
April1st to 15thDay
46%5%15%21%8%1
1941
16th to endDay
56%5%12%17%7%
2145
May1st to 15thDay
53%6%13%18%8%
2161
16th to endDay
43%8%14%22%10%1
2397
June1st to 15thDay
45%7%16%22%7%
2343
16th to endDay
32%7%15%28%14%2
2475
July1st to 15thDay
27%8%17%30%12%3
2278
16th to endDay
27%6%17%27%17%2
2175
August1st to 15thDay
37%10%13%24%11%2
2131
16th to endDay
32%6%15%27%14%3
2248
September1st to 15thDay
35%6%13%24%18%
1942
16th to endDay
34%5%14%31%13%
1810
October1st to 15thDay
39%413%24%16%1
1650
16th to endDay
43%415%24%11%
1757
November1st to 15thDay
38%414%22%18%1
1475
16th to endDay
47%5%19%17%8%
1440
December1st to 15thDay
60%5%11%13%8%1
1440
16th to endDay
61%5%11%15%5%
1536
January1st to 15thNight
49%5%13%21%9%
2455
16th to endNight
53%7%15%16%6%
2496
February1st to 15thNight
51%6%12%20%8%
2288
16th to endNight
45%7%12%20%12%1
2015
March1st to 15thNight
44%5%14%24%9%1
1991
16th to endNight
50%6%13%21%6%
2013
April1st to 15thNight
42%6%12%25%12%
1673
16th to endNight
50%6%9%20%11%2
1485
May1st to 15thNight
43%6%15%19%14%2
1459
16th to endNight
38%8%14%22%13%2
1370
June1st to 15thNight
34%8%19%27%9%
1283
16th to endNight
22%8%14%29%21%3
1155
July1st to 15thNight
19%6%17%32%19%4
1120
16th to endNight
19%6%18%31%20%4
1419
August1st to 15thNight
25%6%14%31%19%2
1475
16th to endNight
25%5%14%30%18%4
1602
September1st to 15thNight
28%414%28%21%1
1686
16th to endNight
29%5%12%33%16%1
1815
October1st to 15thNight
35%311%26%19%3
1974
16th to endNight
42%415%23%14%
2113
November1st to 15thNight
39%412%21%19%2
2383
16th to endNight
44%6%17%20%10%1
2520
December1st to 15thNight
54%6%13%17%7%
2520
16th to endNight
59%5%10%16%6%
2688

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
15%12%36%25%7%2
90
16th to endDay
20%13%41%17%6%
96
February1st to 15thDay
16%20%41%18%3
90
16th to endDay
25%12%25%27%8%
81
March1st to 15thDay
15%21%34%27%1
90
16th to endDay
25%8%35%20%8%
67
April1st to 15thDay
20%13%33%22%8%1
180
16th to endDay
30%13%28%18%8%1
375
May1st to 15thDay
23%15%30%21%5%2
393
16th to endDay
17%10%31%24%13%3
437
June1st to 15thDay
17%6%33%26%13%2
420
16th to endDay
8%5%33%34%15%2
420
July1st to 15thDay
8%5%27%31%21%6%
400
16th to endDay
7%426%35%21%4
445
August1st to 15thDay
7%423%35%25%2
418
16th to endDay
12%423%33%21%4
416
September1st to 15thDay
15%326%32%17%4
217
16th to endDay
20%6%28%22%12%10%
90
October1st to 15thDay
10%13%43%18%10%4
90
16th to endDay
15%11%40%17%13%1
96
November1st to 15thDay
5%8%31%38%10%5%
90
16th to endDay
36%8%33%16%4
90
December1st to 15thDay
23%14%34%20%6%1
90
16th to endDay
36%18%31%11%2
96
January1st to 15thNight
12%12%42%24%6%1
900
16th to endNight
15%14%39%26%4
960
February1st to 15thNight
17%12%38%24%7%
880
16th to endNight
11%13%41%22%9%1
753
March1st to 15thNight
14%9%38%27%9%
551
16th to endNight
21%8%32%28%8%1
549
April1st to 15thNight
20%9%38%24%6%
494
16th to endNight
24%9%32%22%8%2
495
May1st to 15thNight
18%10%36%25%8%
495
16th to endNight
14%7%31%33%13%
515
June1st to 15thNight
13%5%29%41%9%
495
16th to endNight
6%330%46%13%
495
July1st to 15thNight
4228%38%24%
465
16th to endNight
325%47%21%1
522
August1st to 15thNight
6%123%42%23%2
494
16th to endNight
10%222%40%20%3
525
September1st to 15thNight
10%226%38%18%2
495
16th to endNight
11%6%34%29%15%2
492
October1st to 15thNight
16%10%35%26%10%1
654
16th to endNight
20%8%30%30%9%
705
November1st to 15thNight
14%13%36%25%10%
875
16th to endNight
15%13%39%24%7%
900
December1st to 15thNight
18%12%39%24%5%
900
16th to endNight
24%10%33%24%6%
960
Page generated at 2017-03-23 06:36:15. Version ac04

Copyright 2017 A. Danko


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