Monroe
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Monroe clear sky chart from 2005-11-05 to 2017-09-16.

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%
15807
16%
46942
10%
15768
43%
15768
19%
32421

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
18%
897
10%
2506
5%
895
23%
895
12%
1962
January16th to endNight
22%
816
9%
2544
4%
816
28%
816
10%
1975
February1st to 15thNight
21%
701
10%
2255
4%
701
28%
701
12%
1696
February16th to endNight
28%
631
14%
1893
6%
631
35%
631
13%
1404
March1st to 15thNight
30%
720
14%
2070
9%
720
34%
720
17%
1503
March16th to endNight
36%
768
18%
2112
11%
768
42%
768
21%
1475
April1st to 15thNight
34%
599
15%
1823
9%
599
40%
599
19%
1247
April16th to endNight
38%
540
20%
1620
7%
540
49%
540
21%
1053
May1st to 15thNight
36%
540
14%
1620
8%
540
42%
540
17%
1129
May16th to endNight
46%
562
16%
1684
11%
561
51%
561
25%
1049
June1st to 15thNight
50%
540
15%
1476
10%
540
56%
540
27%
945
June16th to endNight
51%
540
17%
1440
11%
540
57%
540
29%
916
July1st to 15thNight
63%
510
16%
1360
14%
510
66%
510
35%
821
July16th to endNight
63%
564
19%
1531
16%
531
70%
531
37%
852
August1st to 15thNight
62%
539
20%
1609
15%
536
66%
536
33%
929
August16th to endNight
61%
573
22%
1740
17%
573
66%
573
32%
1018
September1st to 15thNight
58%
675
24%
1935
17%
675
62%
675
32%
1183
September16th to endNight
59%
661
24%
1826
17%
661
64%
661
31%
1140
October1st to 15thNight
45%
660
21%
1897
18%
660
50%
660
25%
1239
October16th to endNight
28%
704
16%
2192
9%
704
38%
704
18%
1508
November1st to 15thNight
38%
700
20%
2276
18%
700
43%
700
21%
1462
November16th to endNight
23%
720
14%
2346
8%
720
31%
720
13%
1735
December1st to 15thNight
18%
720
8%
2520
4%
720
24%
720
10%
1973
December16th to endNight
16%
927
8%
2667
2%
927
22%
927
9%
2207

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%36%6%35%5%5%7%34%
47795
Night
15%8%36%5%3445%6%36%
47123
Cloud CoverDay
13%7%36%6%35%5%5%7%34%
47805
Night
15%8%36%5%3445%6%36%
47127
TransparencyDay
45%5%13%21%11%1
47494
Night
48%411%21%12%1
46942
SeeingDay
14%10%15%29%23%7%
5791
Night
16%17%19%27%15%3
15814

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
19%13%5%7%8%35%5%46%19%
1432
16th to endDay
14%16%7%10%8%45%45%5%17%
1678
February1st to 15thDay
15%12%410%7%5%5%445%24%
1604
16th to endDay
14%10%410%8%4446%7%23%
1580
March1st to 15thDay
17%10%5%7%6%35%5%5%6%26%
1878
16th to endDay
19%8%47%5%35%35%6%30%
2112
April1st to 15thDay
18%7%46%6%35%45%6%30%
2133
16th to endDay
15%7%45%5%24347%38%
2340
May1st to 15thDay
15%8%47%5%35%447%33%
2331
16th to endDay
10%5%35%5%35%5%6%7%40%
2431
June1st to 15thDay
9%5%25%5%35%5%6%8%41%
2481
16th to endDay
7%5%35%6%37%6%8%9%36%
2520
July1st to 15thDay
6%4245%45%5%6%7%45%
2520
16th to endDay
7%4145%35%6%7%10%42%
2528
August1st to 15thDay
6%425%6%36%6%6%8%43%
2340
16th to endDay
8%425%5%45%6%6%10%40%
2459
September1st to 15thDay
11%5%245%3446%7%44%
2013
16th to endDay
11%4244346%7%7%42%
1824
October1st to 15thDay
13%6%26%5%23447%42%
1733
16th to endDay
20%7%246%4445%6%32%
1679
November1st to 15thDay
13%6%35%5%245%6%6%39%
1582
16th to endDay
18%10%28%5%335%5%7%28%
1609
December1st to 15thDay
17%11%7%9%6%35%5%46%21%
1440
16th to endDay
19%14%7%11%7%24445%17%
1548
January1st to 15thNight
21%13%46%5%34445%24%
2506
16th to endNight
14%12%7%9%7%46%5%4422%
2544
February1st to 15thNight
15%13%6%7%7%34346%26%
2253
16th to endNight
16%10%47%6%45%445%29%
1893
March1st to 15thNight
17%9%5%7%5%3435%5%32%
2058
16th to endNight
16%7%36%6%34446%36%
2112
April1st to 15thNight
18%7%344345%5%6%34%
1823
16th to endNight
15%6%25%4246%46%39%
1620
May1st to 15thNight
18%5%37%6%35%45%7%33%
1620
16th to endNight
11%5%26%5%2445%8%43%
1682
June1st to 15thNight
10%425%435%5%6%6%44%
1476
16th to endNight
9%4245%35%5%6%10%43%
1440
July1st to 15thNight
7%313424449%52%
1440
16th to endNight
5%32342446%9%52%
1637
August1st to 15thNight
4315%426%6%6%9%48%
1620
16th to endNight
9%4145%2445%7%50%
1740
September1st to 15thNight
9%5%24434446%50%
1935
16th to endNight
11%5%2442445%7%47%
1826
October1st to 15thNight
14%5%25%43345%7%43%
1897
16th to endNight
20%6%26%42445%5%36%
2192
November1st to 15thNight
14%6%25%43446%6%41%
2276
16th to endNight
21%9%47%6%34346%28%
2346
December1st to 15thNight
20%12%5%8%6%35%35%6%23%
2520
16th to endNight
22%14%5%9%6%34445%17%
2667

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
19%13%5%7%9%35%5%46%19%
1432
16th to endDay
14%16%7%9%8%35%45%5%17%
1678
February1st to 15thDay
15%12%5%10%7%45%445%24%
1604
16th to endDay
14%10%5%10%8%4446%7%23%
1580
March1st to 15thDay
18%9%5%7%6%35%45%6%26%
1889
16th to endDay
19%8%47%5%35%45%6%30%
2111
April1st to 15thDay
18%7%46%6%36%5%5%6%30%
2133
16th to endDay
15%7%35%5%24347%39%
2340
May1st to 15thDay
15%8%46%5%35%45%7%33%
2331
16th to endDay
11%5%35%5%35%5%6%7%40%
2431
June1st to 15thDay
9%5%26%5%35%5%6%8%41%
2481
16th to endDay
8%5%25%6%37%6%8%9%36%
2520
July1st to 15thDay
6%4245%36%5%7%7%46%
2520
16th to endDay
7%4245%35%6%7%10%42%
2528
August1st to 15thDay
6%426%5%36%6%5%8%43%
2340
16th to endDay
8%4245%35%6%6%10%41%
2459
September1st to 15thDay
11%4245%3445%7%45%
2013
16th to endDay
12%5%244346%6%7%42%
1824
October1st to 15thDay
13%6%26%5%24447%42%
1733
16th to endDay
20%7%246%4445%6%32%
1679
November1st to 15thDay
13%6%345%2446%6%40%
1582
16th to endDay
18%10%38%5%335%5%7%28%
1609
December1st to 15thDay
18%11%7%8%6%25%5%47%21%
1440
16th to endDay
19%13%7%11%7%24446%17%
1548
January1st to 15thNight
21%13%46%5%34445%24%
2506
16th to endNight
15%13%6%9%7%46%45%5%22%
2544
February1st to 15thNight
15%13%5%8%6%34346%26%
2246
16th to endNight
16%10%47%6%36%445%29%
1893
March1st to 15thNight
18%9%47%5%2435%5%32%
2070
16th to endNight
16%6%36%6%3435%6%36%
2112
April1st to 15thNight
18%7%344346%5%5%34%
1823
16th to endNight
16%6%25%4246%46%39%
1620
May1st to 15thNight
18%5%37%5%3446%7%33%
1619
16th to endNight
11%5%36%42445%8%43%
1682
June1st to 15thNight
10%425%435%5%6%7%44%
1476
16th to endNight
10%4145%35%5%6%10%43%
1440
July1st to 15thNight
7%31442445%9%52%
1440
16th to endNight
5%313425%46%9%52%
1637
August1st to 15thNight
43145%25%6%7%8%48%
1620
16th to endNight
9%4145%34348%50%
1740
September1st to 15thNight
9%4244235%46%50%
1935
16th to endNight
11%42443345%7%47%
1826
October1st to 15thNight
14%5%245%2445%7%43%
1897
16th to endNight
20%7%26%42445%5%36%
2192
November1st to 15thNight
14%6%35%42446%6%41%
2276
16th to endNight
21%10%47%5%34346%28%
2346
December1st to 15thNight
20%12%5%8%6%25%35%6%23%
2520
16th to endNight
22%14%6%9%7%24445%18%
2667

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
65%6%11%12%4
1433
16th to endDay
66%5%11%10%4
1678
February1st to 15thDay
60%5%11%16%6%
1606
16th to endDay
58%413%17%41
1580
March1st to 15thDay
57%5%13%16%5%1
1889
16th to endDay
51%412%23%6%
2112
April1st to 15thDay
51%5%12%19%12%
2133
16th to endDay
43%313%22%13%4
2340
May1st to 15thDay
47%413%21%11%2
2331
16th to endDay
38%5%13%27%13%1
2435
June1st to 15thDay
36%5%15%26%14%1
2481
16th to endDay
36%8%16%19%16%2
2520
July1st to 15thDay
32%5%13%26%19%2
2371
16th to endDay
31%6%16%27%16%2
2371
August1st to 15thDay
33%5%15%29%14%1
2327
16th to endDay
34%6%15%24%16%2
2459
September1st to 15thDay
36%6%13%27%14%1
2013
16th to endDay
36%6%12%29%14%
1824
October1st to 15thDay
41%5%12%23%14%1
1733
16th to endDay
50%415%21%8%
1679
November1st to 15thDay
42%6%11%23%14%1
1582
16th to endDay
55%413%19%6%
1609
December1st to 15thDay
65%5%10%13%5%
1440
16th to endDay
67%413%10%3
1548
January1st to 15thNight
62%410%15%7%
2506
16th to endNight
64%314%13%4
2544
February1st to 15thNight
59%411%17%5%1
2255
16th to endNight
58%310%20%6%
1893
March1st to 15thNight
53%411%19%9%1
2070
16th to endNight
48%311%24%10%1
2112
April1st to 15thNight
49%310%20%14%
1823
16th to endNight
43%311%19%17%3
1620
May1st to 15thNight
50%410%20%11%2
1620
16th to endNight
39%410%26%15%2
1684
June1st to 15thNight
37%5%11%28%16%
1476
16th to endNight
35%6%13%24%18%1
1440
July1st to 15thNight
30%6%11%28%21%2
1360
16th to endNight
25%6%16%26%21%3
1531
August1st to 15thNight
29%6%15%29%17%2
1609
16th to endNight
33%412%25%20%3
1740
September1st to 15thNight
35%410%27%18%2
1935
16th to endNight
36%5%10%30%16%1
1826
October1st to 15thNight
41%5%11%22%18%1
1897
16th to endNight
49%412%23%8%1
2192
November1st to 15thNight
44%411%22%14%2
2276
16th to endNight
58%311%19%6%
2346
December1st to 15thNight
64%411%13%5%
2520
16th to endNight
68%5%11%10%4
2667

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
18%12%35%20%12%1
90
16th to endDay
30%5%28%31%5%
96
February1st to 15thDay
23%6%37%24%7%
90
16th to endDay
18%425%38%12%
81
March1st to 15thDay
21%15%20%31%11%
179
16th to endDay
18%12%21%32%11%2
288
April1st to 15thDay
16%14%22%30%13%1
270
16th to endDay
19%12%18%29%14%5%
270
May1st to 15thDay
18%12%16%28%20%3
288
16th to endDay
12%10%14%28%27%7%
331
June1st to 15thDay
8%13%10%38%23%4
456
16th to endDay
12%14%12%32%21%7%
495
July1st to 15thDay
6%9%7%32%34%10%
475
16th to endDay
6%11%5%26%35%13%
388
August1st to 15thDay
10%7%429%34%14%
313
16th to endDay
11%6%6%25%34%15%
332
September1st to 15thDay
11%5%11%22%29%18%
315
16th to endDay
19%7%9%16%31%14%
257
October1st to 15thDay
12%9%18%24%25%9%
255
16th to endDay
23%7%24%31%13%
191
November1st to 15thDay
11%5%18%26%32%5%
90
16th to endDay
21%11%21%36%9%
88
December1st to 15thDay
18%15%30%31%31
60
16th to endDay
23%6%43%26%
93
January1st to 15thNight
22%21%27%21%6%
900
16th to endNight
16%22%25%28%6%
816
February1st to 15thNight
20%18%28%27%5%
704
16th to endNight
18%18%23%30%8%
631
March1st to 15thNight
18%19%21%29%9%
720
16th to endNight
17%19%18%31%11%2
768
April1st to 15thNight
18%19%21%31%8%1
599
16th to endNight
18%18%18%28%12%2
540
May1st to 15thNight
17%18%16%26%17%2
540
16th to endNight
11%18%13%29%20%5%
563
June1st to 15thNight
12%17%12%34%20%2
540
16th to endNight
10%17%12%32%22%3
540
July1st to 15thNight
9%12%7%31%32%6%
510
16th to endNight
5%17%7%34%27%6%
564
August1st to 15thNight
7%11%9%35%26%8%
539
16th to endNight
9%9%9%25%36%9%
573
September1st to 15thNight
11%10%10%26%30%9%
675
16th to endNight
13%10%9%26%32%8%
661
October1st to 15thNight
18%13%16%26%18%6%
660
16th to endNight
22%16%26%26%7%
704
November1st to 15thNight
14%18%23%26%13%3
700
16th to endNight
24%24%23%19%8%
720
December1st to 15thNight
24%22%28%20%4
720
16th to endNight
23%21%28%21%5%
927
Page generated at 2017-09-17 12:05:42. Version ac04

Copyright 2017 A. Danko


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