Norfolk(NE)
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Norfolk(NE) clear sky chart from 2005-11-06 to 2024-01-15.

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 Type	Minimum conditions for hour to be usable				Out of hours
	Clear of Clouds	Transparency	Seeing	Sky Brightness
Planetary:	50%	(no limit)	Average	(no limit)	Nighttime Hours
Deep Sky:	70%	Average	(no limit)	5.9	Nighttime Hours
CCD Imaging:	70%	Below Average	Poor	(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

By Month

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 Forecast	Data Points
Cloud Cover	Day	11% 7% 3 6% 5% 3 4 4 5% 7% 45%	74872
	Night	10% 6% 3 6% 5% 3 4 4 5% 7% 48%	74901
Transparency	Day	38% 5% 14% 26% 14% 2	74584
	Night	36% 5% 13% 27% 16% 3	74709
Seeing	Day	14% 9% 31% 29% 13% 2	14675
	Night	13% 10% 35% 32% 9% 1	24709

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
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	9% 10% 4 7% 6% 4 4 4 4 7% 40%	1518
	11th to 20th	Day	8% 10% 5% 10% 6% 3 4 5% 5% 7% 39%	1622
	21st to end	Day	8% 11% 4 12% 7% 4 5% 5% 5% 6% 34%	1782
February	1st to 10th	Day	10% 9% 5% 8% 7% 4 5% 5% 5% 6% 34%	1620
	11th to 20th	Day	8% 9% 5% 7% 5% 3 5% 4 6% 6% 41%	1659
	21st to end	Day	10% 11% 4 8% 6% 3 5% 5% 4 6% 39%	1480
March	1st to 10th	Day	11% 9% 4 6% 4 2 3 4 4 7% 47%	1885
	11th to 20th	Day	12% 9% 4 6% 5% 3 4 4 5% 8% 40%	1980
	21st to end	Day	17% 13% 4 7% 5% 3 5% 5% 4 6% 30%	2178
April	1st to 10th	Day	13% 8% 4 6% 6% 3 4 3 5% 7% 42%	2008
	11th to 20th	Day	18% 8% 3 5% 5% 3 4 4 5% 7% 38%	2312
	21st to end	Day	19% 8% 3 5% 4 2 3 4 5% 7% 39%	2340
May	1st to 10th	Day	15% 7% 3 6% 5% 3 5% 5% 5% 8% 38%	2340
	11th to 20th	Day	14% 8% 3 6% 5% 3 5% 4 6% 6% 41%	2302
	21st to end	Day	18% 6% 3 5% 5% 4 5% 5% 5% 8% 37%	2531
June	1st to 10th	Day	8% 4 2 5% 5% 2 4 4 5% 10% 50%	2528
	11th to 20th	Day	11% 5% 2 5% 4 3 5% 4 6% 9% 46%	2700
	21st to end	Day	7% 5% 1 4 4 3 4 4 6% 9% 52%	2648
July	1st to 10th	Day	7% 3 2 4 4 3 4 4 7% 10% 52%	2520
	11th to 20th	Day	6% 3 1 4 4 2 4 5% 6% 6% 58%	2434
	21st to end	Day	5% 3 2 4 5% 3 5% 5% 7% 10% 53%	2546
August	1st to 10th	Day	8% 6% 3 7% 6% 4 5% 6% 6% 9% 39%	2328
	11th to 20th	Day	10% 4 3 4 4 3 4 4 6% 8% 51%	2301
	21st to end	Day	9% 4 2 4 4 2 4 4 5% 8% 54%	2574
September	1st to 10th	Day	13% 5% 2 4 4 3 4 5% 4 7% 50%	2041
	11th to 20th	Day	9% 5% 1 4 4 2 3 3 5% 7% 56%	1980
	21st to end	Day	11% 4 1 3 4 2 3 3 5% 7% 57%	1980
October	1st to 10th	Day	16% 5% 2 4 4 2 3 3 4 5% 50%	1891
	11th to 20th	Day	11% 5% 2 3 4 2 3 3 4 7% 57%	1800
	21st to end	Day	15% 6% 2 5% 4 3 3 3 4 6% 50%	1904
November	1st to 10th	Day	8% 6% 3 4 5% 3 4 3 5% 7% 52%	1673
	11th to 20th	Day	9% 7% 2 5% 7% 2 4 4 4 7% 48%	1710
	21st to end	Day	11% 9% 3 6% 4 2 3 4 5% 8% 45%	1534
December	1st to 10th	Day	8% 8% 3 7% 5% 3 4 5% 4 6% 47%	1520
	11th to 20th	Day	6% 8% 4 7% 8% 4 6% 5% 6% 8% 39%	1918
	21st to end	Day	15% 9% 4 12% 6% 3 4 4 6% 6% 31%	2785
January	1st to 10th	Night	7% 8% 3 6% 6% 5% 6% 6% 6% 7% 40%	2647
	11th to 20th	Night	7% 9% 4 9% 7% 3 5% 5% 5% 7% 40%	2420
	21st to end	Night	10% 10% 4 7% 6% 3 4 4 5% 7% 40%	2574
February	1st to 10th	Night	11% 10% 4 8% 7% 3 5% 3 4 5% 40%	2340
	11th to 20th	Night	8% 8% 4 6% 5% 3 6% 5% 6% 6% 43%	2205
	21st to end	Night	10% 6% 3 6% 6% 3 5% 4 5% 6% 46%	1776
March	1st to 10th	Night	10% 8% 3 6% 4 3 4 4 5% 6% 47%	2074
	11th to 20th	Night	13% 8% 4 5% 4 2 4 4 4 6% 46%	1980
	21st to end	Night	15% 9% 4 7% 5% 4 5% 4 5% 7% 36%	2178
April	1st to 10th	Night	14% 7% 3 6% 5% 3 4 4 5% 6% 44%	1948
	11th to 20th	Night	13% 8% 3 6% 5% 3 4 4 5% 7% 43%	1599
	21st to end	Night	15% 7% 2 5% 3 3 4 5% 6% 8% 43%	1620
May	1st to 10th	Night	14% 6% 2 4 5% 3 4 4 6% 8% 44%	1620
	11th to 20th	Night	13% 6% 2 6% 4 3 4 4 6% 8% 45%	1593
	21st to end	Night	16% 7% 2 4 4 3 3 5% 6% 11% 40%	1745
June	1st to 10th	Night	6% 3 2 2 4 2 5% 5% 7% 8% 56%	1423
	11th to 20th	Night	8% 4 2 5% 4 2 4 3 5% 7% 57%	1260
	21st to end	Night	3 3 2 4 3 2 4 5% 6% 7% 60%	1304
July	1st to 10th	Night	6% 4 2 4 3 3 4 4 5% 9% 56%	1440
	11th to 20th	Night	3 2 1 3 3 3 4 5% 5% 9% 61%	1523
	21st to end	Night	3 3 2 3 5% 2 4 5% 5% 9% 58%	1772
August	1st to 10th	Night	5% 4 3 5% 5% 3 5% 5% 6% 10% 48%	1611
	11th to 20th	Night	6% 4 2 3 4 2 4 3 6% 9% 58%	1600
	21st to end	Night	7% 3 2 4 4 2 3 3 5% 9% 58%	1782
September	1st to 10th	Night	8% 3 1 4 3 2 3 4 5% 6% 59%	1915
	11th to 20th	Night	8% 4 2 4 3 2 4 4 4 6% 60%	1980
	21st to end	Night	9% 4 2 4 3 2 3 3 4 6% 60%	1980
October	1st to 10th	Night	16% 5% 2 4 3 2 4 3 4 5% 50%	2050
	11th to 20th	Night	12% 5% 2 3 3 2 3 3 5% 5% 56%	2160
	21st to end	Night	14% 5% 1 4 4 2 3 3 4 6% 54%	2450
November	1st to 10th	Night	7% 5% 2 3 3 2 3 4 5% 6% 60%	2405
	11th to 20th	Night	9% 6% 2 6% 5% 3 3 4 5% 6% 51%	2470
	21st to end	Night	9% 7% 3 5% 3 2 3 4 5% 7% 52%	2644
December	1st to 10th	Night	7% 7% 4 7% 6% 3 4 3 5% 7% 47%	2660
	11th to 20th	Night	8% 7% 4 5% 4 3 4 4 6% 8% 46%	3279
	21st to end	Night	15% 11% 5% 12% 6% 3 4 4 4 5% 33%	4874

Transparency (when cloud cover <= 30%)
Color Meanings: Too cloudy to forecast Poor Below Average Average Above average Transparent
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	46% 5% 15% 22% 12% 1	1519
	11th to 20th	Day	45% 4 15% 23% 13% 1	1622
	21st to end	Day	51% 5% 16% 18% 9% 1	1782
February	1st to 10th	Day	49% 5% 15% 18% 11% 1	1620
	11th to 20th	Day	43% 6% 11% 23% 14% 3	1668
	21st to end	Day	45% 5% 12% 22% 12% 3	1480
March	1st to 10th	Day	38% 5% 13% 28% 13% 2	1885
	11th to 20th	Day	43% 6% 12% 24% 13% 2	1980
	21st to end	Day	54% 5% 14% 17% 7% 2	2178
April	1st to 10th	Day	44% 4 12% 25% 13% 1	2008
	11th to 20th	Day	45% 4 12% 22% 13% 3	2312
	21st to end	Day	45% 5% 12% 27% 11%	2340
May	1st to 10th	Day	43% 6% 14% 21% 14% 1	2340
	11th to 20th	Day	44% 4 17% 24% 11%	2306
	21st to end	Day	46% 6% 14% 22% 11% 1	2531
June	1st to 10th	Day	30% 7% 18% 31% 13% 2	2528
	11th to 20th	Day	33% 7% 15% 25% 17% 3	2700
	21st to end	Day	28% 7% 17% 32% 13% 4	2648
July	1st to 10th	Day	28% 6% 18% 30% 17% 2	2451
	11th to 20th	Day	26% 5% 14% 31% 18% 6%	2359
	21st to end	Day	24% 8% 15% 33% 18% 2	2405
August	1st to 10th	Day	39% 7% 16% 25% 11% 2	2314
	11th to 20th	Day	32% 6% 14% 32% 14% 2	2301
	21st to end	Day	29% 6% 12% 27% 21% 5%	2574
September	1st to 10th	Day	35% 5% 12% 25% 18% 5%	2041
	11th to 20th	Day	29% 5% 12% 36% 17% 2	1980
	21st to end	Day	28% 4 9% 33% 25% 1	1980
October	1st to 10th	Day	37% 4 8% 26% 23% 2	1891
	11th to 20th	Day	29% 3 12% 31% 19% 6%	1800
	21st to end	Day	38% 3 12% 25% 19% 3	1904
November	1st to 10th	Day	32% 4 15% 26% 21% 2	1673
	11th to 20th	Day	37% 5% 12% 27% 18% 2	1710
	21st to end	Day	39% 4 12% 27% 14% 3	1534
December	1st to 10th	Day	38% 4 17% 26% 11% 3	1520
	11th to 20th	Day	42% 5% 16% 29% 8%	1915
	21st to end	Day	53% 6% 10% 21% 9% 1	2785
January	1st to 10th	Night	41% 5% 13% 25% 14% 1	2647
	11th to 20th	Night	44% 4 14% 27% 10% 1	2420
	21st to end	Night	44% 4 16% 24% 11% 1	2574
February	1st to 10th	Night	47% 4 13% 22% 12% 2	2340
	11th to 20th	Night	40% 6% 14% 23% 13% 4	2206
	21st to end	Night	38% 5% 13% 25% 16% 4	1776
March	1st to 10th	Night	38% 5% 13% 29% 13% 3	2074
	11th to 20th	Night	41% 4 10% 26% 17% 3	1980
	21st to end	Night	48% 5% 16% 22% 9% 1	2178
April	1st to 10th	Night	40% 6% 11% 26% 16% 1	1948
	11th to 20th	Night	40% 6% 10% 27% 15% 2	1599
	21st to end	Night	38% 6% 13% 26% 15% 2	1620
May	1st to 10th	Night	38% 5% 14% 26% 15% 1	1620
	11th to 20th	Night	37% 7% 15% 26% 15%	1594
	21st to end	Night	40% 6% 17% 22% 14% 1	1746
June	1st to 10th	Night	24% 8% 17% 34% 15% 3	1423
	11th to 20th	Night	28% 4 15% 28% 19% 5%	1260
	21st to end	Night	21% 6% 15% 36% 18% 3	1304
July	1st to 10th	Night	26% 5% 15% 31% 20% 4	1400
	11th to 20th	Night	20% 7% 15% 30% 21% 7%	1475
	21st to end	Night	22% 6% 18% 30% 21% 3	1673
August	1st to 10th	Night	31% 7% 17% 28% 15% 2	1601
	11th to 20th	Night	24% 6% 14% 33% 19% 3	1600
	21st to end	Night	25% 5% 13% 25% 24% 7%	1782
September	1st to 10th	Night	26% 5% 11% 30% 22% 7%	1915
	11th to 20th	Night	26% 4 11% 34% 22% 3	1980
	21st to end	Night	27% 4 9% 31% 25% 4	1980
October	1st to 10th	Night	37% 4 9% 24% 24% 1	2050
	11th to 20th	Night	30% 4 8% 27% 26% 5%	2160
	21st to end	Night	33% 3 14% 24% 23% 3	2450
November	1st to 10th	Night	26% 4 15% 27% 24% 4	2405
	11th to 20th	Night	33% 4 13% 27% 19% 4	2470
	21st to end	Night	33% 4 13% 29% 19% 3	2644
December	1st to 10th	Night	37% 4 15% 29% 14% 1	2660
	11th to 20th	Night	35% 4 16% 34% 10% 1	3281
	21st to end	Night	54% 4 10% 22% 8% 1	4874

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
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	18% 13% 35% 21% 11% 1	270
	11th to 20th	Day	18% 15% 34% 25% 8% 1	252
	21st to end	Day	14% 9% 47% 25% 6%	264
February	1st to 10th	Day	14% 18% 41% 26% 2	240
	11th to 20th	Day	14% 15% 40% 25% 5% 1	240
	21st to end	Day	16% 20% 40% 20% 4	198
March	1st to 10th	Day	15% 17% 42% 18% 6% 1	240
	11th to 20th	Day	20% 10% 41% 19% 8% 1	240
	21st to end	Day	28% 16% 32% 16% 7% 1	264
April	1st to 10th	Day	19% 17% 42% 18% 4	268
	11th to 20th	Day	22% 16% 33% 22% 7%	590
	21st to end	Day	24% 14% 31% 22% 8% 2	600
May	1st to 10th	Day	20% 11% 34% 24% 10% 1	603
	11th to 20th	Day	20% 12% 30% 23% 13% 2	625
	21st to end	Day	19% 8% 30% 29% 12% 2	679
June	1st to 10th	Day	6% 7% 28% 33% 22% 4	630
	11th to 20th	Day	11% 5% 33% 33% 15% 3	630
	21st to end	Day	9% 7% 30% 34% 17% 2	630
July	1st to 10th	Day	9% 4 20% 34% 29% 5%	621
	11th to 20th	Day	5% 2 27% 42% 19% 5%	618
	21st to end	Day	6% 2 24% 44% 21% 3	684
August	1st to 10th	Day	10% 4 20% 41% 23% 2	626
	11th to 20th	Day	12% 4 22% 37% 21% 4	615
	21st to end	Day	11% 3 26% 36% 21% 4	693
September	1st to 10th	Day	14% 4 27% 39% 12% 4	331
	11th to 20th	Day	8% 6% 38% 29% 14% 4	270
	21st to end	Day	14% 12% 31% 29% 11% 3	270
October	1st to 10th	Day	23% 8% 26% 27% 13% 3	270
	11th to 20th	Day	16% 14% 36% 23% 9% 3	270
	21st to end	Day	19% 15% 36% 21% 7% 1	297
November	1st to 10th	Day	16% 14% 34% 26% 7% 4	270
	11th to 20th	Day	13% 16% 44% 22% 6%	270
	21st to end	Day	18% 17% 32% 25% 8%	270
December	1st to 10th	Day	11% 13% 43% 26% 6% 1	270
	11th to 20th	Day	15% 14% 38% 27% 7%	270
	21st to end	Day	18% 17% 41% 19% 4 1	297
January	1st to 10th	Night	13% 14% 38% 28% 6% 1	950
	11th to 20th	Night	12% 14% 38% 29% 6% 1	921
	21st to end	Night	16% 10% 44% 25% 5%	990
February	1st to 10th	Night	15% 13% 41% 27% 4	900
	11th to 20th	Night	13% 11% 43% 27% 6%	811
	21st to end	Night	14% 11% 42% 28% 6%	592
March	1st to 10th	Night	14% 14% 40% 27% 4	634
	11th to 20th	Night	17% 11% 39% 28% 6%	540
	21st to end	Night	20% 8% 40% 25% 7%	594
April	1st to 10th	Night	19% 13% 39% 25% 4	540
	11th to 20th	Night	16% 14% 38% 27% 5%	533
	21st to end	Night	17% 13% 34% 27% 9%	540
May	1st to 10th	Night	17% 9% 34% 30% 9%	540
	11th to 20th	Night	15% 8% 32% 33% 10% 1	531
	21st to end	Night	18% 7% 31% 33% 11% 1	584
June	1st to 10th	Night	8% 4 25% 47% 15% 1	540
	11th to 20th	Night	9% 6% 33% 39% 12% 1	540
	21st to end	Night	5% 6% 28% 47% 14%	540
July	1st to 10th	Night	6% 4 18% 46% 25% 1	525
	11th to 20th	Night	4 1 24% 51% 20% 1	522
	21st to end	Night	3 3 21% 57% 17% 1	591
August	1st to 10th	Night	5% 3 21% 48% 22% 1	537
	11th to 20th	Night	8% 4 22% 46% 21%	534
	21st to end	Night	7% 3 29% 42% 18% 1	594
September	1st to 10th	Night	9% 4 27% 41% 16% 2	540
	11th to 20th	Night	9% 6% 32% 37% 14% 2	540
	21st to end	Night	12% 9% 34% 32% 14%	540
October	1st to 10th	Night	19% 7% 34% 29% 10%	610
	11th to 20th	Night	14% 14% 37% 27% 7%	720
	21st to end	Night	17% 11% 32% 30% 10%	866
November	1st to 10th	Night	10% 11% 38% 32% 7% 1	925
	11th to 20th	Night	13% 12% 40% 30% 6%	950
	21st to end	Night	14% 12% 37% 29% 9%	950
December	1st to 10th	Night	12% 12% 45% 26% 5% 1	950
	11th to 20th	Night	15% 11% 37% 29% 7%	950
	21st to end	Night	18% 14% 39% 24% 6%	1045

Page generated at 2024-01-11 21:33:50. Version ac07

Copyright 2024 Attilla Danko