North Raymer
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the North Raymer clear sky chart from 2005-11-05 to 2017-09-24.

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
49%
16003
25%
46934
16%
15960
57%
15960
36%
27034

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
44%
900
27%
2506
16%
895
53%
895
39%
1419
January16th to endNight
38%
885
29%
2613
14%
885
52%
885
38%
1454
February1st to 15thNight
35%
700
21%
2213
8%
698
49%
698
30%
1302
February16th to endNight
37%
632
28%
1894
14%
632
50%
632
34%
1095
March1st to 15thNight
44%
720
25%
2160
15%
720
54%
720
36%
1202
March16th to endNight
39%
641
22%
2000
14%
641
49%
641
32%
1159
April1st to 15thNight
38%
539
19%
1798
13%
539
49%
539
27%
1074
April16th to endNight
35%
540
18%
1779
14%
540
44%
540
22%
1133
May1st to 15thNight
43%
540
18%
1598
14%
540
49%
540
27%
1043
May16th to endNight
43%
561
15%
1498
9%
561
48%
561
26%
1024
June1st to 15thNight
56%
540
15%
1440
8%
540
61%
540
37%
889
June16th to endNight
65%
540
22%
1440
15%
540
68%
540
45%
812
July1st to 15thNight
65%
510
16%
1360
12%
510
67%
510
34%
857
July16th to endNight
73%
564
25%
1416
21%
531
74%
531
45%
801
August1st to 15thNight
65%
539
17%
1638
18%
536
67%
536
31%
1006
August16th to endNight
68%
573
25%
1910
28%
573
72%
573
41%
974
September1st to 15thNight
61%
540
27%
1800
26%
540
67%
540
36%
975
September16th to endNight
64%
519
34%
1902
32%
519
73%
519
46%
850
October1st to 15thNight
49%
599
29%
1919
21%
599
56%
599
35%
1052
October16th to endNight
56%
786
33%
2194
20%
786
63%
786
46%
1182
November1st to 15thNight
52%
875
30%
2275
16%
875
58%
875
46%
1279
November16th to endNight
49%
900
33%
2373
16%
900
60%
900
45%
1344
December1st to 15thNight
39%
900
22%
2520
9%
900
48%
900
36%
1487
December16th to endNight
41%
960
26%
2688
13%
960
51%
960
34%
1621

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
6%42442445%8%53%
48016
Night
6%5%2442445%7%52%
47106
Cloud CoverDay
6%42442445%8%52%
48014
Night
6%5%2442445%7%52%
47106
TransparencyDay
28%5%12%26%19%6%
47690
Night
30%5%12%25%19%6%
46934
SeeingDay
10%6%24%30%21%6%
5943
Night
8%5%30%39%14%
16009

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
36%34434346%55%
1432
16th to endDay
35%2432346%8%55%
1623
February1st to 15thDay
37%47%42446%7%46%
1648
16th to endDay
36%26%5%2445%6%52%
1580
March1st to 15thDay
5%424434348%53%
1800
16th to endDay
8%6%345%245%47%45%
2220
April1st to 15thDay
9%7%24323446%50%
2150
16th to endDay
13%7%244235%48%42%
2181
May1st to 15thDay
12%4235%345%5%7%44%
2352
16th to endDay
10%4244245%6%9%45%
2616
June1st to 15thDay
8%2123245%6%9%52%
2520
16th to endDay
211232445%8%63%
2520
July1st to 15thDay
6%313325%5%6%9%51%
2520
16th to endDay
3213425%5%7%9%52%
2656
August1st to 15thDay
4314335%5%8%11%48%
2311
16th to endDay
5%21231436%8%59%
2292
September1st to 15thDay
8%212323347%60%
2160
16th to endDay
6%22212336%65%
1916
October1st to 15thDay
11%412212348%56%
1708
16th to endDay
7%413312336%62%
1667
November1st to 15thDay
35%2332345%6%59%
1583
16th to endDay
35%24223347%60%
1585
December1st to 15thDay
47%25%5%2445%7%48%
1440
16th to endDay
5%8%345%24447%49%
1536
January1st to 15thNight
35%34323448%55%
2506
16th to endNight
45%35%32335%6%56%
2613
February1st to 15thNight
47%36%32445%8%48%
2203
16th to endNight
47%25%424345%53%
1894
March1st to 15thNight
4435%42445%6%55%
2160
16th to endNight
7%6%2442345%7%49%
2000
April1st to 15thNight
10%6%24424446%48%
1798
16th to endNight
15%7%24433446%42%
1779
May1st to 15thNight
14%5%243445%5%7%42%
1597
16th to endNight
12%5%245%35%6%6%7%41%
1497
June1st to 15thNight
6%324425%47%11%48%
1440
16th to endNight
3214435%46%8%56%
1440
July1st to 15thNight
7%325%5%35%5%6%8%46%
1440
16th to endNight
43133146%8%10%51%
1512
August1st to 15thNight
5%3245%37%6%6%9%44%
1646
16th to endNight
5%3133245%5%7%56%
1910
September1st to 15thNight
8%31442336%7%53%
1800
16th to endNight
5%312312347%64%
1902
October1st to 15thNight
11%423313346%55%
1919
16th to endNight
7%323322336%62%
2194
November1st to 15thNight
4423324446%59%
2275
16th to endNight
45%13423346%59%
2373
December1st to 15thNight
5%6%36%42436%7%50%
2520
16th to endNight
6%7%35%424446%50%
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
36%25%5%23346%55%
1432
16th to endDay
35%3432346%8%55%
1623
February1st to 15thDay
37%46%42446%7%47%
1648
16th to endDay
36%26%5%2435%6%51%
1580
March1st to 15thDay
4424434349%53%
1800
16th to endDay
8%7%345%245%5%7%45%
2218
April1st to 15thDay
9%6%2432445%6%49%
2150
16th to endDay
13%6%2442445%8%41%
2181
May1st to 15thDay
12%5%24425%5%6%7%44%
2352
16th to endDay
10%4245%245%6%8%45%
2616
June1st to 15thDay
8%212225%5%6%10%52%
2520
16th to endDay
211232346%9%62%
2520
July1st to 15thDay
6%313325%5%6%9%50%
2520
16th to endDay
3213435%5%7%10%52%
2656
August1st to 15thDay
4314435%5%8%10%48%
2311
16th to endDay
5%21332446%8%59%
2292
September1st to 15thDay
8%31232335%7%59%
2160
16th to endDay
6%313213245%66%
1916
October1st to 15thDay
10%413212347%56%
1708
16th to endDay
7%423312336%62%
1667
November1st to 15thDay
35%2442335%7%58%
1583
16th to endDay
35%2322335%7%59%
1585
December1st to 15thDay
46%35%5%2445%8%48%
1440
16th to endDay
5%8%34433447%49%
1536
January1st to 15thNight
25%3441445%7%55%
2506
16th to endNight
35%35%323446%56%
2613
February1st to 15thNight
37%36%32445%8%48%
2203
16th to endNight
37%35%424445%53%
1894
March1st to 15thNight
45%25%425%45%5%54%
2160
16th to endNight
7%6%2442345%8%49%
2000
April1st to 15thNight
10%6%24434346%48%
1798
16th to endNight
14%8%24424436%43%
1779
May1st to 15thNight
12%5%25%4345%5%7%42%
1597
16th to endNight
11%5%245%346%6%8%41%
1497
June1st to 15thNight
6%324425%47%11%48%
1440
16th to endNight
3213435%46%8%56%
1440
July1st to 15thNight
7%315%5%36%5%6%8%45%
1440
16th to endNight
43124246%8%10%51%
1512
August1st to 15thNight
4325%6%36%6%7%9%44%
1646
16th to endNight
43133245%5%8%56%
1910
September1st to 15thNight
8%41343346%8%51%
1800
16th to endNight
431331335%7%63%
1902
October1st to 15thNight
10%423313346%55%
1919
16th to endNight
6%323223336%61%
2194
November1st to 15thNight
4424323447%58%
2275
16th to endNight
3424423446%59%
2373
December1st to 15thNight
5%5%35%42436%7%50%
2520
16th to endNight
5%7%34424347%50%
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
30%414%32%15%2
1433
16th to endDay
26%416%30%18%3
1623
February1st to 15thDay
35%5%13%32%9%3
1649
16th to endDay
31%410%30%18%3
1580
March1st to 15thDay
30%412%26%22%4
1800
16th to endDay
36%415%24%13%5%
2220
April1st to 15thDay
34%5%12%26%14%6%
2150
16th to endDay
39%6%12%22%15%3
2181
May1st to 15thDay
37%6%12%27%14%1
2352
16th to endDay
34%8%15%24%12%4
2620
June1st to 15thDay
26%7%16%23%18%7%
2520
16th to endDay
17%5%9%27%27%11%
2520
July1st to 15thDay
27%6%11%24%19%11%
2371
16th to endDay
23%7%12%28%19%8%
2489
August1st to 15thDay
26%7%15%24%15%9%
2295
16th to endDay
20%49%25%28%10%
2292
September1st to 15thDay
23%49%23%23%14%
2160
16th to endDay
20%37%26%34%7%
1916
October1st to 15thDay
28%411%23%24%7%
1708
16th to endDay
24%410%29%23%8%
1667
November1st to 15thDay
25%313%25%22%10%
1583
16th to endDay
24%39%29%26%6%
1585
December1st to 15thDay
33%5%13%32%12%2
1440
16th to endDay
35%5%12%27%15%4
1536
January1st to 15thNight
27%414%27%21%3
2506
16th to endNight
29%311%28%23%4
2613
February1st to 15thNight
33%6%14%28%13%3
2213
16th to endNight
31%410%27%19%6%
1894
March1st to 15thNight
29%410%25%23%6%
2160
16th to endNight
32%5%14%22%20%3
2000
April1st to 15thNight
36%6%12%25%15%4
1798
16th to endNight
41%6%10%22%16%3
1779
May1st to 15thNight
39%7%14%24%12%2
1598
16th to endNight
39%10%17%18%8%5%
1498
June1st to 15thNight
28%9%19%22%12%6%
1440
16th to endNight
24%6%13%27%20%7%
1440
July1st to 15thNight
34%6%12%23%13%9%
1360
16th to endNight
24%6%15%28%19%6%
1416
August1st to 15thNight
32%9%16%21%13%7%
1638
16th to endNight
24%412%24%23%9%
1910
September1st to 15thNight
29%5%10%22%21%10%
1800
16th to endNight
20%38%32%26%8%
1902
October1st to 15thNight
29%412%22%22%8%
1919
16th to endNight
25%311%27%23%9%
2194
November1st to 15thNight
24%411%22%25%11%
2275
16th to endNight
26%310%26%25%7%
2373
December1st to 15thNight
31%414%30%14%3
2520
16th to endNight
33%414%28%16%2
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
7%10%30%31%13%7%
90
16th to endDay
7%7%44%31%8%1
96
February1st to 15thDay
11%12%41%31%4
90
16th to endDay
6%8%39%27%18%
81
March1st to 15thDay
5%13%41%22%16%1
90
16th to endDay
15%12%33%27%10%
270
April1st to 15thDay
13%16%35%23%9%2
269
16th to endDay
21%19%27%18%10%1
291
May1st to 15thDay
14%7%29%28%16%3
468
16th to endDay
15%7%24%25%20%5%
517
June1st to 15thDay
9%422%32%21%9%
495
16th to endDay
6%321%38%25%5%
495
July1st to 15thDay
11%114%32%32%7%
475
16th to endDay
3113%36%34%9%
515
August1st to 15thDay
6%219%36%28%6%
376
16th to endDay
5%321%32%29%8%
332
September1st to 15thDay
7%225%33%21%10%
315
16th to endDay
8%126%23%26%14%
126
October1st to 15thDay
12%5%16%35%20%10%
90
16th to endDay
9%327%30%16%13%
96
November1st to 15thDay
2322%26%26%18%
90
16th to endDay
18%13%26%23%16%1
90
December1st to 15thDay
11%441%35%7%
90
16th to endDay
8%9%36%36%7%2
96
January1st to 15thNight
49%35%37%12%1
900
16th to endNight
7%6%43%32%8%
885
February1st to 15thNight
7%6%42%35%7%
704
16th to endNight
7%8%40%37%5%
632
March1st to 15thNight
6%8%36%38%10%
720
16th to endNight
9%9%35%34%9%
641
April1st to 15thNight
13%10%33%34%6%
539
16th to endNight
19%9%31%31%8%
540
May1st to 15thNight
16%6%29%35%12%
540
16th to endNight
14%430%32%16%1
563
June1st to 15thNight
6%429%42%16%
540
16th to endNight
3124%52%16%
540
July1st to 15thNight
8%13%48%25%2
510
16th to endNight
412%48%32%1
564
August1st to 15thNight
5%116%48%26%1
539
16th to endNight
7%17%47%26%
573
September1st to 15thNight
10%120%42%22%2
540
16th to endNight
6%221%45%22%1
519
October1st to 15thNight
14%7%25%32%18%2
599
16th to endNight
8%6%24%42%17%1
786
November1st to 15thNight
6%5%30%41%14%1
875
16th to endNight
5%5%33%41%13%
900
December1st to 15thNight
7%6%40%37%7%
900
16th to endNight
9%8%33%40%7%
960
Page generated at 2017-09-25 07:02:25. Version ac04

Copyright 2017 A. Danko


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