Goodwood
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Goodwood clear sky chart from 2005-11-06 to 2024-11-04.

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	15% 10% 4 8% 5% 5% 5% 4 6% 7% 32%	101484
	Night	15% 10% 3 8% 5% 5% 5% 4 5% 6% 33%	97506
Transparency	Day	48% 8% 13% 20% 10% 1	105086
	Night	47% 8% 13% 21% 11% 1	101992
Seeing	Day	20% 16% 31% 21% 9% 3	14425
	Night	20% 14% 32% 24% 9% 1	23770

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
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	16% 14% 5% 9% 6% 5% 4 2 4 5% 28%	2517
	11th to 20th	Day	10% 18% 7% 16% 8% 6% 5% 3 4 4 17%	2708
	21st to end	Day	20% 20% 7% 12% 5% 5% 5% 3 4 4 15%	3124
February	1st to 10th	Day	15% 17% 5% 12% 7% 7% 5% 4 5% 5% 19%	1710
	11th to 20th	Day	11% 16% 7% 12% 7% 5% 4 3 5% 6% 24%	1663
	21st to end	Day	16% 17% 4 11% 5% 5% 5% 3 4 4 25%	1457
March	1st to 10th	Day	17% 12% 5% 9% 6% 4 5% 3 4 5% 31%	3432
	11th to 20th	Day	10% 15% 5% 10% 7% 6% 5% 4 5% 6% 28%	3480
	21st to end	Day	16% 10% 3 8% 6% 4 4 3 5% 5% 35%	3815
April	1st to 10th	Day	18% 14% 4 8% 5% 5% 4 3 5% 6% 27%	2256
	11th to 20th	Day	20% 10% 3 6% 4 3 4 3 5% 5% 35%	2315
	21st to end	Day	20% 10% 3 8% 5% 4 4 3 5% 6% 32%	2470
May	1st to 10th	Day	19% 8% 3 8% 5% 4 4 3 5% 8% 33%	4131
	11th to 20th	Day	16% 10% 3 8% 6% 4 5% 4 6% 8% 32%	4398
	21st to end	Day	12% 5% 2 6% 4 4 4 3 5% 7% 45%	4837
June	1st to 10th	Day	16% 8% 3 6% 5% 4 5% 4 6% 8% 35%	2660
	11th to 20th	Day	12% 7% 3 6% 5% 4 5% 4 6% 10% 38%	2660
	21st to end	Day	15% 6% 3 6% 5% 5% 5% 4 6% 9% 36%	2660
July	1st to 10th	Day	11% 6% 2 6% 5% 5% 6% 5% 7% 9% 37%	4440
	11th to 20th	Day	10% 5% 2 6% 4 5% 6% 4 7% 9% 40%	4440
	21st to end	Day	8% 5% 2 7% 6% 5% 6% 5% 7% 9% 40%	4568
August	1st to 10th	Day	16% 8% 3 6% 5% 4 5% 4 7% 8% 35%	4104
	11th to 20th	Day	12% 6% 3 8% 5% 4 5% 5% 7% 9% 35%	4044
	21st to end	Day	10% 6% 2 7% 4 4 5% 4 6% 8% 43%	4345
September	1st to 10th	Day	13% 6% 3 7% 5% 4 4 4 7% 6% 42%	2280
	11th to 20th	Day	12% 5% 2 6% 4 4 4 4 6% 8% 44%	2188
	21st to end	Day	15% 6% 3 8% 6% 5% 5% 4 5% 6% 38%	2038
October	1st to 10th	Day	18% 9% 4 8% 4 4 4 3 5% 7% 34%	1900
	11th to 20th	Day	19% 11% 3 10% 5% 4 4 4 5% 5% 29%	1900
	21st to end	Day	23% 14% 4 9% 5% 5% 4 3 5% 6% 22%	2090
November	1st to 10th	Day	15% 11% 4 9% 6% 4 5% 3 5% 7% 31%	1616
	11th to 20th	Day	16% 12% 4 11% 6% 6% 6% 5% 6% 6% 23%	1520
	21st to end	Day	19% 15% 4 11% 7% 5% 6% 3 4 5% 20%	1520
December	1st to 10th	Day	15% 17% 6% 14% 8% 7% 5% 4 5% 5% 13%	1520
	11th to 20th	Day	17% 15% 4 9% 7% 5% 5% 4 5% 7% 21%	1906
	21st to end	Day	26% 18% 5% 13% 6% 5% 5% 3 3 3 12%	2772
January	1st to 10th	Night	17% 15% 5% 10% 7% 6% 5% 4 5% 6% 20%	4429
	11th to 20th	Night	13% 13% 5% 16% 9% 7% 5% 4 5% 6% 17%	4248
	21st to end	Night	19% 14% 6% 10% 6% 6% 5% 4 5% 6% 19%	4532
February	1st to 10th	Night	13% 17% 4 10% 6% 7% 6% 5% 5% 5% 22%	2470
	11th to 20th	Night	13% 15% 5% 10% 6% 5% 5% 4 6% 6% 25%	2403
	21st to end	Night	14% 12% 4 11% 6% 6% 4 4 6% 6% 27%	1994
March	1st to 10th	Night	16% 11% 3 9% 6% 5% 5% 3 5% 5% 32%	3408
	11th to 20th	Night	12% 11% 4 9% 7% 4 5% 3 5% 6% 34%	3479
	21st to end	Night	15% 8% 2 8% 5% 5% 5% 3 5% 6% 38%	3817
April	1st to 10th	Night	19% 12% 3 6% 6% 4 4 3 5% 6% 31%	1923
	11th to 20th	Night	16% 9% 3 7% 4 5% 4 4 5% 6% 37%	1830
	21st to end	Night	16% 8% 4 9% 6% 4 3 4 6% 8% 34%	1710
May	1st to 10th	Night	17% 8% 3 6% 4 4 4 3 5% 7% 39%	2806
	11th to 20th	Night	15% 8% 3 6% 4 5% 4 3 6% 7% 38%	2495
	21st to end	Night	10% 5% 2 5% 4 4 4 3 5% 8% 50%	2738
June	1st to 10th	Night	12% 7% 2 7% 5% 5% 4 4 6% 8% 40%	1520
	11th to 20th	Night	9% 5% 3 7% 5% 4 5% 4 6% 8% 43%	1520
	21st to end	Night	12% 6% 2 7% 5% 4 4 4 6% 8% 42%	1496
July	1st to 10th	Night	7% 5% 2 5% 5% 4 4 5% 6% 8% 50%	2520
	11th to 20th	Night	11% 4 2 5% 3 4 4 3 6% 8% 50%	2520
	21st to end	Night	7% 5% 2 5% 4 4 4 4 6% 8% 51%	2982
August	1st to 10th	Night	9% 6% 2 7% 4 4 4 4 6% 7% 47%	2825
	11th to 20th	Night	11% 5% 2 6% 4 3 4 3 5% 7% 49%	2785
	21st to end	Night	9% 6% 3 6% 4 4 4 3 5% 7% 48%	3278
September	1st to 10th	Night	9% 6% 2 6% 4 5% 5% 3 6% 7% 47%	1900
	11th to 20th	Night	11% 4 1 4 4 3 3 3 5% 7% 53%	1989
	21st to end	Night	16% 7% 3 6% 4 4 4 3 5% 8% 41%	2140
October	1st to 10th	Night	15% 7% 3 9% 4 5% 4 4 6% 6% 38%	2280
	11th to 20th	Night	18% 9% 3 8% 5% 6% 4 4 5% 6% 33%	2280
	21st to end	Night	21% 10% 3 7% 6% 5% 5% 3 5% 6% 28%	2508
November	1st to 10th	Night	18% 10% 3 7% 5% 4 4 4 5% 7% 35%	2529
	11th to 20th	Night	16% 11% 4 9% 6% 6% 5% 3 5% 7% 27%	2660
	21st to end	Night	18% 14% 3 9% 6% 6% 5% 5% 6% 6% 22%	2660
December	1st to 10th	Night	18% 16% 5% 11% 7% 6% 5% 4 4 6% 17%	2660
	11th to 20th	Night	15% 19% 5% 11% 6% 6% 5% 4 5% 5% 20%	3288
	21st to end	Night	27% 16% 4 13% 6% 5% 5% 3 4 5% 12%	4884

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	57% 8% 16% 12% 7% 1	2518
	11th to 20th	Day	69% 7% 10% 10% 5%	2708
	21st to end	Day	69% 8% 9% 9% 4 1	3124
February	1st to 10th	Day	65% 7% 9% 14% 4 1	1710
	11th to 20th	Day	59% 8% 9% 16% 7% 1	1672
	21st to end	Day	60% 7% 9% 16% 7% 1	1457
March	1st to 10th	Day	53% 7% 13% 17% 10%	3435
	11th to 20th	Day	53% 8% 12% 18% 8% 1	3480
	21st to end	Day	45% 9% 10% 19% 15% 2	3815
April	1st to 10th	Day	55% 7% 10% 17% 10% 1	2256
	11th to 20th	Day	49% 6% 10% 20% 14% 1	2315
	21st to end	Day	50% 7% 11% 17% 13% 2	2470
May	1st to 10th	Day	47% 7% 12% 19% 12% 2	4143
	11th to 20th	Day	48% 9% 13% 20% 9% 1	4402
	21st to end	Day	36% 7% 15% 23% 16% 3	4837
June	1st to 10th	Day	44% 9% 13% 20% 14% 1	2660
	11th to 20th	Day	40% 8% 12% 23% 16% 1	2660
	21st to end	Day	43% 8% 14% 22% 13% 1	2660
July	1st to 10th	Day	37% 8% 16% 23% 14% 1	4370
	11th to 20th	Day	34% 10% 14% 33% 9%	4365
	21st to end	Day	35% 10% 14% 24% 16%	4422
August	1st to 10th	Day	44% 7% 14% 22% 11% 1	4091
	11th to 20th	Day	41% 8% 15% 27% 9%	4083
	21st to end	Day	36% 7% 14% 33% 10% 1	4345
September	1st to 10th	Day	39% 8% 14% 28% 10% 1	2280
	11th to 20th	Day	34% 9% 13% 28% 14%	2188
	21st to end	Day	45% 7% 13% 25% 9%	2038
October	1st to 10th	Day	38% 6% 15% 26% 14% 1	3160
	11th to 20th	Day	41% 7% 15% 23% 14%	3140
	21st to end	Day	52% 8% 15% 19% 6%	3428
November	1st to 10th	Day	50% 9% 14% 18% 8% 1	1616
	11th to 20th	Day	56% 11% 12% 13% 8% 1	1520
	21st to end	Day	63% 8% 11% 15% 3	1520
December	1st to 10th	Day	67% 10% 10% 10% 3	1520
	11th to 20th	Day	59% 12% 12% 12% 6%	1906
	21st to end	Day	74% 8% 7% 8% 2	2772
January	1st to 10th	Night	60% 10% 14% 11% 5%	4429
	11th to 20th	Night	64% 10% 12% 11% 3 1	4248
	21st to end	Night	63% 8% 12% 11% 4 1	4532
February	1st to 10th	Night	60% 9% 10% 17% 5% 1	2470
	11th to 20th	Night	56% 8% 11% 17% 8%	2405
	21st to end	Night	54% 7% 13% 18% 8% 1	1994
March	1st to 10th	Night	52% 6% 12% 21% 8% 1	3418
	11th to 20th	Night	47% 8% 15% 20% 9% 1	3480
	21st to end	Night	39% 10% 11% 22% 16% 2	3817
April	1st to 10th	Night	52% 6% 9% 19% 13% 1	1923
	11th to 20th	Night	47% 7% 9% 20% 16% 2	1830
	21st to end	Night	46% 7% 12% 18% 15% 2	1710
May	1st to 10th	Night	44% 7% 13% 18% 16% 3	2813
	11th to 20th	Night	43% 8% 15% 22% 11% 2	2496
	21st to end	Night	31% 7% 15% 25% 20% 2	2739
June	1st to 10th	Night	40% 8% 11% 24% 16% 2	1520
	11th to 20th	Night	37% 7% 12% 22% 21% 2	1520
	21st to end	Night	39% 7% 13% 23% 16% 1	1496
July	1st to 10th	Night	31% 6% 16% 25% 20% 2	2480
	11th to 20th	Night	31% 6% 14% 34% 15% 1	2472
	21st to end	Night	28% 8% 15% 31% 16% 1	2887
August	1st to 10th	Night	35% 5% 14% 28% 15% 2	2814
	11th to 20th	Night	33% 6% 17% 31% 12% 1	2812
	21st to end	Night	33% 7% 13% 33% 13% 1	3278
September	1st to 10th	Night	35% 8% 15% 27% 14% 1	1900
	11th to 20th	Night	30% 6% 12% 32% 18% 1	1989
	21st to end	Night	42% 6% 13% 27% 12%	2140
October	1st to 10th	Night	32% 6% 10% 28% 24% 1	3800
	11th to 20th	Night	41% 8% 14% 26% 12%	3779
	21st to end	Night	41% 8% 16% 26% 9%	4120
November	1st to 10th	Night	46% 8% 13% 22% 11% 1	2529
	11th to 20th	Night	54% 9% 12% 14% 9% 1	2660
	21st to end	Night	56% 11% 16% 13% 4	2660
December	1st to 10th	Night	64% 9% 12% 12% 4	2660
	11th to 20th	Night	63% 9% 10% 13% 4	3288
	21st to end	Night	71% 9% 10% 8% 3	4884

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	23% 24% 29% 18% 6%	180
	11th to 20th	Day	23% 31% 26% 15% 3 1	232
	21st to end	Day	24% 25% 36% 13% 2	297
February	1st to 10th	Day	27% 27% 31% 12% 3	270
	11th to 20th	Day	24% 27% 40% 8% 1	270
	21st to end	Day	35% 23% 34% 8%	252
March	1st to 10th	Day	24% 22% 36% 15% 3	460
	11th to 20th	Day	23% 23% 33% 17% 3 1	460
	21st to end	Day	31% 19% 30% 15% 4 1	506
April	1st to 10th	Day	27% 20% 34% 13% 6%	460
	11th to 20th	Day	31% 20% 25% 15% 7% 2	452
	21st to end	Day	27% 16% 35% 13% 7% 1	460
May	1st to 10th	Day	23% 14% 31% 19% 8% 4	463
	11th to 20th	Day	18% 16% 30% 25% 8% 3	487
	21st to end	Day	16% 12% 30% 27% 12% 4	529
June	1st to 10th	Day	16% 16% 30% 28% 9% 1	490
	11th to 20th	Day	14% 15% 30% 26% 12% 2	490
	21st to end	Day	22% 9% 32% 25% 10% 2	490
July	1st to 10th	Day	10% 9% 28% 33% 17% 4	485
	11th to 20th	Day	15% 7% 28% 30% 14% 6%	484
	21st to end	Day	8% 8% 34% 33% 11% 6%	532
August	1st to 10th	Day	13% 9% 27% 30% 15% 8%	486
	11th to 20th	Day	13% 9% 23% 28% 21% 6%	479
	21st to end	Day	13% 10% 29% 26% 15% 7%	539
September	1st to 10th	Day	13% 11% 27% 27% 15% 7%	490
	11th to 20th	Day	10% 8% 26% 25% 20% 12%	490
	21st to end	Day	17% 12% 29% 26% 12% 6%	490
October	1st to 10th	Day	21% 14% 30% 16% 16% 3	490
	11th to 20th	Day	22% 21% 32% 17% 7% 1	490
	21st to end	Day	28% 22% 28% 17% 5%	539
November	1st to 10th	Day	24% 22% 31% 15% 6% 1	265
	11th to 20th	Day	23% 26% 32% 15% 4 1	180
	21st to end	Day	24% 26% 39% 10% 2	180
December	1st to 10th	Day	24% 22% 36% 13% 4 1	180
	11th to 20th	Day	31% 21% 33% 12% 3 1	180
	21st to end	Day	30% 22% 36% 12% 1	198
January	1st to 10th	Night	23% 23% 36% 13% 5%	760
	11th to 20th	Night	28% 17% 33% 18% 4 1	760
	21st to end	Night	20% 16% 37% 21% 6%	836
February	1st to 10th	Night	21% 21% 38% 18% 2	760
	11th to 20th	Night	23% 19% 36% 19% 3	743
	21st to end	Night	22% 21% 37% 15% 4	628
March	1st to 10th	Night	20% 20% 37% 19% 3	760
	11th to 20th	Night	21% 21% 36% 17% 4 1	760
	21st to end	Night	20% 17% 33% 24% 6%	836
April	1st to 10th	Night	25% 17% 34% 21% 3	760
	11th to 20th	Night	19% 18% 35% 20% 8% 1	706
	21st to end	Night	20% 14% 34% 24% 9%	570
May	1st to 10th	Night	20% 9% 28% 30% 11% 2	556
	11th to 20th	Night	17% 7% 32% 30% 13% 1	374
	21st to end	Night	11% 8% 27% 36% 17% 1	411
June	1st to 10th	Night	14% 8% 31% 36% 12%	380
	11th to 20th	Night	11% 9% 30% 36% 13% 1	380
	21st to end	Night	15% 6% 30% 36% 12% 1	380
July	1st to 10th	Night	7% 6% 28% 39% 19% 1	370
	11th to 20th	Night	12% 4 29% 35% 21% 1	368
	21st to end	Night	10% 3 26% 41% 18% 2	558
August	1st to 10th	Night	10% 4 21% 36% 26% 2	567
	11th to 20th	Night	8% 4 19% 41% 24% 3	564
	21st to end	Night	12% 5% 28% 34% 19% 3	716
September	1st to 10th	Night	12% 8% 25% 33% 18% 4	760
	11th to 20th	Night	12% 8% 22% 29% 23% 5%	760
	21st to end	Night	18% 9% 23% 31% 15% 4	760
October	1st to 10th	Night	19% 8% 30% 25% 16% 2	760
	11th to 20th	Night	23% 16% 31% 22% 8% 1	760
	21st to end	Night	28% 14% 32% 22% 3	836
November	1st to 10th	Night	24% 14% 31% 23% 8% 1	755
	11th to 20th	Night	22% 19% 32% 19% 6% 1	760
	21st to end	Night	25% 18% 30% 21% 5%	760
December	1st to 10th	Night	28% 18% 35% 16% 3	760
	11th to 20th	Night	21% 20% 37% 18% 3 1	760
	21st to end	Night	30% 17% 36% 15% 2	836

Page generated at 2024-11-01 22:47:36. Version ac07

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