Harrisburg
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Harrisburg clear sky chart from 2005-11-05 to 2018-02-13.

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
42%
16400
22%
48744
15%
16354
49%
16354
28%
30533

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
23%
975
19%
2716
7%
970
32%
970
20%
1895
January16th to endNight
22%
1040
19%
2748
6%
1040
31%
1040
23%
1876
February1st to 15thNight
20%
778
17%
2282
6%
775
28%
775
18%
1605
February16th to endNight
21%
631
19%
1893
6%
631
32%
631
20%
1267
March1st to 15thNight
23%
720
17%
2160
7%
720
31%
720
20%
1464
March16th to endNight
31%
600
17%
2001
10%
600
40%
600
20%
1320
April1st to 15thNight
32%
539
22%
1797
12%
539
47%
539
27%
1072
April16th to endNight
39%
540
22%
1800
17%
540
50%
540
26%
1115
May1st to 15thNight
42%
539
18%
1640
11%
539
50%
539
26%
1069
May16th to endNight
55%
563
20%
1584
15%
561
59%
561
31%
1016
June1st to 15thNight
65%
540
22%
1440
16%
540
69%
540
42%
855
June16th to endNight
68%
540
24%
1440
17%
540
71%
540
44%
816
July1st to 15thNight
70%
510
19%
1360
16%
510
71%
510
39%
822
July16th to endNight
73%
564
25%
1423
21%
531
77%
531
45%
809
August1st to 15thNight
77%
539
23%
1780
27%
536
78%
536
41%
918
August16th to endNight
73%
573
25%
1910
28%
573
76%
573
36%
1040
September1st to 15thNight
66%
543
28%
1803
29%
543
69%
543
32%
1024
September16th to endNight
60%
717
32%
1980
24%
717
65%
717
39%
1151
October1st to 15thNight
53%
720
30%
2055
22%
720
59%
720
37%
1200
October16th to endNight
37%
768
29%
2378
18%
768
50%
768
30%
1419
November1st to 15thNight
42%
760
29%
2471
23%
760
53%
760
32%
1398
November16th to endNight
33%
780
26%
2535
18%
780
44%
780
27%
1505
December1st to 15thNight
29%
881
18%
2636
10%
881
38%
881
21%
1790
December16th to endNight
19%
1040
18%
2912
5%
1040
31%
1040
19%
2087

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
12%6%25%5%345%5%7%42%
49307
Night
13%6%25%424446%45%
48921
TransparencyDay
40%5%11%24%14%2
48987
Night
39%410%24%17%3
48746
SeeingDay
14%8%23%25%19%8%
6255
Night
16%9%27%28%16%2
16401

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
18%8%38%5%335%4433%
1552
16th to endDay
11%8%47%5%34445%40%
1827
February1st to 15thDay
14%10%47%424435%38%
1844
16th to endDay
10%9%37%6%35%5%5%6%35%
1580
March1st to 15thDay
19%8%26%6%23445%37%
1800
16th to endDay
16%8%35%5%35%5%5%7%32%
2230
April1st to 15thDay
12%5%25%5%3435%7%44%
2151
16th to endDay
15%7%25%5%24446%39%
2160
May1st to 15thDay
17%425%5%35%5%6%8%35%
2310
16th to endDay
9%6%26%6%446%7%8%38%
2527
June1st to 15thDay
8%324435%5%6%9%46%
2520
16th to endDay
5%3245%36%6%7%10%44%
2520
July1st to 15thDay
10%4245%35%5%6%9%41%
2520
16th to endDay
4314447%7%7%10%44%
2646
August1st to 15thDay
6%4245%26%5%5%10%43%
2169
16th to endDay
7%424435%7%7%9%44%
2292
September1st to 15thDay
10%5%26%5%35%5%5%6%43%
2145
16th to endDay
10%42342335%7%50%
1980
October1st to 15thDay
11%5%24433346%50%
1902
16th to endDay
14%423424346%50%
1845
November1st to 15thDay
11%435%3335%5%5%48%
1717
16th to endDay
18%6%24423235%46%
1755
December1st to 15thDay
16%9%35%5%3445%6%37%
1651
16th to endDay
17%11%35%424345%36%
1664
January1st to 15thNight
16%8%37%5%23435%38%
2716
16th to endNight
13%7%35%5%3445%5%40%
2748
February1st to 15thNight
17%9%47%5%23335%36%
2273
16th to endNight
13%7%36%6%3445%439%
1893
March1st to 15thNight
16%8%35%5%24335%39%
2160
16th to endNight
17%6%25%435%446%38%
2001
April1st to 15thNight
13%5%144245%46%48%
1797
16th to endNight
15%5%25%5%2345%6%43%
1800
May1st to 15thNight
15%436%424447%42%
1640
16th to endNight
6%325%6%45%5%6%9%44%
1583
June1st to 15thNight
7%3144235%5%9%51%
1440
16th to endNight
33133345%7%11%51%
1440
July1st to 15thNight
8%324434449%51%
1440
16th to endNight
5%214436%5%7%8%51%
1519
August1st to 15thNight
5%31332445%10%55%
1791
16th to endNight
6%31442446%8%52%
1910
September1st to 15thNight
10%424424347%51%
1803
16th to endNight
9%41442435%6%54%
1980
October1st to 15thNight
11%414423346%53%
2055
16th to endNight
16%5%2431224451%
2378
November1st to 15thNight
11%413323446%52%
2471
16th to endNight
15%5%24423335%49%
2535
December1st to 15thNight
19%9%34323345%38%
2636
16th to endNight
18%9%36%5%24445%35%
2912

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%39%21%10%1
1553
16th to endDay
46%312%26%9%1
1827
February1st to 15thDay
48%311%23%10%1
1846
16th to endDay
48%413%19%11%1
1580
March1st to 15thDay
49%5%8%22%11%1
1800
16th to endDay
49%5%15%21%7%
2232
April1st to 15thDay
38%411%25%17%2
2151
16th to endDay
45%410%26%11%1
2160
May1st to 15thDay
46%7%12%22%10%
2310
16th to endDay
40%9%14%20%12%3
2531
June1st to 15thDay
32%6%13%26%18%2
2520
16th to endDay
31%8%13%22%20%3
2520
July1st to 15thDay
37%7%12%22%15%4
2371
16th to endDay
30%8%16%28%14%1
2479
August1st to 15thDay
34%8%12%26%16%2
2156
16th to endDay
33%6%13%23%17%4
2292
September1st to 15thDay
38%5%8%24%17%4
2145
16th to endDay
32%5%7%27%23%3
1980
October1st to 15thDay
35%49%26%19%5%
1902
16th to endDay
35%37%30%19%3
1845
November1st to 15thDay
36%5%8%22%18%7%
1717
16th to endDay
41%37%28%16%2
1755
December1st to 15thDay
47%413%21%12%1
1651
16th to endDay
51%312%20%10%1
1664
January1st to 15thNight
49%37%21%16%1
2716
16th to endNight
44%412%23%13%1
2748
February1st to 15thNight
51%38%22%11%1
2282
16th to endNight
46%411%23%12%1
1893
March1st to 15thNight
47%49%19%15%4
2160
16th to endNight
45%5%14%22%11%1
2001
April1st to 15thNight
37%410%24%19%3
1797
16th to endNight
41%38%26%16%3
1800
May1st to 15thNight
41%5%11%25%14%1
1641
16th to endNight
35%8%13%21%16%4
1585
June1st to 15thNight
27%6%14%26%22%2
1440
16th to endNight
24%7%15%24%22%5%
1440
July1st to 15thNight
31%5%13%27%15%7%
1360
16th to endNight
25%5%15%34%16%3
1423
August1st to 15thNight
23%6%17%25%23%3
1780
16th to endNight
27%6%12%25%21%5%
1910
September1st to 15thNight
33%47%27%19%7%
1803
16th to endNight
31%38%25%24%6%
1980
October1st to 15thNight
32%39%22%26%6%
2055
16th to endNight
37%35%28%19%6%
2378
November1st to 15thNight
32%49%23%23%7%
2471
16th to endNight
38%28%25%21%2
2535
December1st to 15thNight
48%310%21%14%1
2636
16th to endNight
51%411%20%10%1
2912

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
27%19%35%11%41
135
16th to endDay
15%30%35%14%3
144
February1st to 15thDay
18%26%42%12%
126
16th to endDay
20%23%37%16%2
81
March1st to 15thDay
31%17%36%11%3
90
16th to endDay
19%17%33%19%7%
231
April1st to 15thDay
15%17%31%24%11%
270
16th to endDay
20%11%25%26%12%3
270
May1st to 15thDay
19%13%28%23%11%3
288
16th to endDay
15%7%28%23%16%8%
427
June1st to 15thDay
10%318%30%25%10%
495
16th to endDay
7%427%34%20%5%
495
July1st to 15thDay
14%216%34%19%11%
475
16th to endDay
5%19%28%36%18%
515
August1st to 15thDay
12%8%25%31%21%
322
16th to endDay
13%111%25%33%15%
332
September1st to 15thDay
11%312%22%31%18%
315
16th to endDay
12%312%24%30%16%
314
October1st to 15thDay
14%426%29%18%7%
237
16th to endDay
13%11%33%29%11%
144
November1st to 15thDay
10%14%30%23%18%2
135
16th to endDay
27%15%27%23%5%
135
December1st to 15thDay
11%24%37%17%5%4
135
16th to endDay
25%25%42%6%
144
January1st to 15thNight
22%18%33%22%3
975
16th to endNight
17%16%40%22%2
1040
February1st to 15thNight
23%16%35%22%2
778
16th to endNight
18%17%38%23%1
631
March1st to 15thNight
21%15%37%23%2
720
16th to endNight
20%9%34%24%9%1
600
April1st to 15thNight
15%13%35%25%8%
539
16th to endNight
18%7%28%29%13%1
540
May1st to 15thNight
17%6%25%36%12%1
540
16th to endNight
8%323%36%23%3
563
June1st to 15thNight
9%117%39%28%2
540
16th to endNight
5%218%44%27%2
540
July1st to 15thNight
10%110%39%34%3
510
16th to endNight
5%19%33%40%9%
564
August1st to 15thNight
8%7%33%40%9%
539
16th to endNight
8%10%34%40%5%
573
September1st to 15thNight
11%312%27%37%6%
543
16th to endNight
11%5%17%27%30%8%
717
October1st to 15thNight
13%5%21%30%23%6%
720
16th to endNight
18%7%32%26%12%1
768
November1st to 15thNight
13%9%30%30%14%1
760
16th to endNight
18%12%31%25%11%
780
December1st to 15thNight
23%13%29%24%6%
881
16th to endNight
22%15%38%20%3
1040
Page generated at 2018-02-13 19:46:04. Version ac04

Copyright 2018 A. Danko


Harrisburg Clear Sky Chart |Charts Home