Doughton Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Doughton Park clear sky chart from 2005-11-06 to 2025-10-19.

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	14% 6% 2 6% 5% 5% 5% 4 6% 8% 39%	126629
	Night	15% 6% 2 5% 4 4 4 4 5% 8% 44%	123078
Transparency	Day	40% 8% 13% 19% 15% 5%	130288
	Night	37% 7% 13% 21% 17% 6%	127488
Seeing	Day	21% 14% 25% 22% 13% 6%	16478
	Night	19% 12% 24% 27% 16% 2	26523

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	12% 5% 2 5% 3 3 3 3 4 6% 54%	4056
	11th to 20th	Day	11% 6% 2 4 3 3 3 3 4 5% 55%	4060
	21st to end	Day	17% 6% 3 6% 3 3 3 2 4 5% 48%	4466
February	1st to 10th	Day	12% 9% 2 6% 4 5% 4 4 6% 6% 41%	1800
	11th to 20th	Day	18% 9% 3 5% 4 3 4 4 5% 5% 41%	1903
	21st to end	Day	18% 7% 2 6% 4 4 4 4 5% 6% 41%	1670
March	1st to 10th	Day	19% 7% 2 5% 4 4 4 3 5% 6% 41%	4935
	11th to 20th	Day	12% 5% 2 5% 3 3 3 3 4 7% 52%	4980
	21st to end	Day	18% 7% 2 5% 4 3 4 3 5% 6% 44%	5465
April	1st to 10th	Day	12% 6% 1 5% 4 4 4 4 6% 7% 47%	2200
	11th to 20th	Day	16% 6% 2 4 4 3 4 4 6% 7% 43%	2383
	21st to end	Day	15% 6% 2 5% 5% 5% 5% 4 6% 6% 41%	2600
May	1st to 10th	Day	13% 7% 3 8% 6% 5% 7% 5% 8% 9% 29%	5862
	11th to 20th	Day	21% 8% 2 7% 5% 5% 5% 4 7% 9% 27%	5861
	21st to end	Day	14% 6% 2 6% 5% 5% 5% 5% 7% 8% 37%	6433
June	1st to 10th	Day	13% 6% 2 6% 6% 6% 6% 4 7% 9% 34%	2600
	11th to 20th	Day	9% 6% 2 6% 6% 6% 6% 5% 7% 11% 34%	2600
	21st to end	Day	9% 5% 2 7% 6% 6% 5% 6% 9% 10% 35%	2600
July	1st to 10th	Day	8% 5% 2 7% 6% 7% 7% 6% 8% 9% 35%	5900
	11th to 20th	Day	8% 6% 3 9% 7% 8% 8% 6% 9% 11% 25%	5900
	21st to end	Day	11% 8% 3 10% 8% 7% 7% 6% 8% 9% 22%	6424
August	1st to 10th	Day	15% 8% 3 8% 6% 6% 6% 6% 8% 10% 24%	4234
	11th to 20th	Day	10% 5% 2 8% 6% 7% 7% 5% 9% 10% 31%	4174
	21st to end	Day	8% 4 2 5% 5% 5% 5% 4 7% 10% 45%	4430
September	1st to 10th	Day	13% 6% 2 6% 5% 4 5% 5% 6% 7% 41%	2232
	11th to 20th	Day	17% 6% 3 7% 4 4 5% 4 6% 8% 35%	2200
	21st to end	Day	22% 7% 2 7% 5% 5% 4 3 5% 6% 34%	2200
October	1st to 10th	Day	17% 5% 2 5% 4 3 3 3 4 6% 49%	2080
	11th to 20th	Day	14% 5% 1 5% 3 4 3 3 4 6% 52%	1980
	21st to end	Day	16% 5% 1 5% 3 2 2 2 4 6% 54%	2090
November	1st to 10th	Day	13% 5% 3 4 4 2 3 3 4 6% 54%	1942
	11th to 20th	Day	13% 5% 1 4 4 3 3 3 5% 6% 53%	1800
	21st to end	Day	14% 6% 2 5% 4 3 4 3 4 6% 49%	1800
December	1st to 10th	Day	12% 9% 2 6% 4 3 3 3 4 5% 49%	2930
	11th to 20th	Day	17% 6% 2 4 3 5% 4 3 5% 7% 44%	3373
	21st to end	Day	21% 7% 2 5% 3 3 4 3 5% 8% 38%	4466
January	1st to 10th	Night	12% 6% 1 4 3 3 3 3 4 7% 53%	5889
	11th to 20th	Night	10% 7% 2 5% 3 3 3 3 5% 6% 53%	5900
	21st to end	Night	17% 6% 2 4 3 3 3 3 4 5% 50%	6490
February	1st to 10th	Night	13% 7% 3 5% 4 4 4 5% 6% 6% 43%	2600
	11th to 20th	Night	19% 7% 3 5% 3 4 4 3 5% 6% 42%	2378
	21st to end	Night	15% 7% 2 7% 5% 4 4 4 5% 6% 41%	1958
March	1st to 10th	Night	21% 7% 2 5% 3 4 4 3 4 5% 42%	4918
	11th to 20th	Night	11% 3 1 4 3 3 4 3 5% 7% 55%	4980
	21st to end	Night	16% 5% 2 5% 4 4 4 4 6% 7% 43%	5467
April	1st to 10th	Night	13% 7% 2 5% 4 4 4 3 5% 8% 45%	2200
	11th to 20th	Night	16% 5% 2 4 4 3 3 3 5% 8% 47%	1975
	21st to end	Night	16% 6% 2 4 3 3 4 3 5% 7% 47%	1804
May	1st to 10th	Night	16% 7% 2 6% 4 4 4 4 6% 11% 36%	4033
	11th to 20th	Night	22% 7% 2 6% 4 4 4 3 5% 9% 34%	4032
	21st to end	Night	18% 5% 2 5% 3 3 4 4 7% 10% 37%	4421
June	1st to 10th	Night	11% 5% 2 5% 4 4 6% 5% 7% 10% 41%	1800
	11th to 20th	Night	12% 6% 2 4 4 5% 5% 4 7% 9% 43%	1800
	21st to end	Night	8% 5% 2 6% 5% 5% 4 5% 8% 10% 44%	1800
July	1st to 10th	Night	10% 6% 2 7% 4 4 5% 5% 8% 10% 38%	4058
	11th to 20th	Night	9% 5% 3 8% 5% 6% 6% 6% 9% 12% 32%	4057
	21st to end	Night	10% 8% 4 9% 7% 6% 6% 5% 8% 10% 26%	4427
August	1st to 10th	Night	15% 8% 4 8% 4 5% 5% 4 7% 10% 30%	2915
	11th to 20th	Night	12% 6% 2 7% 5% 5% 5% 5% 7% 10% 37%	2875
	21st to end	Night	7% 4 1 5% 4 4 4 4 6% 9% 51%	3421
September	1st to 10th	Night	12% 5% 2 7% 3 4 4 5% 6% 7% 45%	2163
	11th to 20th	Night	18% 7% 2 6% 4 4 3 3 6% 7% 41%	2200
	21st to end	Night	22% 6% 2 6% 4 4 4 3 4 5% 39%	2200
October	1st to 10th	Night	16% 7% 2 4 2 3 3 3 4 6% 49%	2319
	11th to 20th	Night	15% 5% 2 4 3 3 3 3 4 6% 52%	2377
	21st to end	Night	15% 4 1 4 3 2 3 2 3 5% 57%	2508
November	1st to 10th	Night	16% 5% 2 4 3 3 3 3 4 5% 52%	2351
	11th to 20th	Night	14% 5% 1 3 3 3 4 3 5% 7% 53%	2600
	21st to end	Night	13% 5% 2 4 3 3 4 3 5% 6% 50%	2600
December	1st to 10th	Night	12% 7% 2 6% 3 3 3 3 4 6% 51%	4250
	11th to 20th	Night	17% 12% 3 6% 3 3 4 3 4 6% 40%	4822
	21st to end	Night	22% 6% 2 4 3 3 4 3 5% 7% 41%	6490

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	31% 6% 8% 20% 29% 7%	4057
	11th to 20th	Day	31% 6% 6% 16% 31% 9%	4060
	21st to end	Day	39% 4 8% 21% 23% 5%	4466
February	1st to 10th	Day	40% 7% 12% 20% 17% 5%	1800
	11th to 20th	Day	44% 5% 11% 18% 18% 5%	1913
	21st to end	Day	42% 7% 12% 16% 17% 6%	1670
March	1st to 10th	Day	41% 6% 9% 16% 15% 13%	4935
	11th to 20th	Day	32% 6% 7% 20% 20% 15%	4980
	21st to end	Day	40% 5% 10% 24% 17% 5%	5465
April	1st to 10th	Day	33% 8% 13% 22% 18% 5%	2200
	11th to 20th	Day	37% 7% 13% 20% 18% 5%	2383
	21st to end	Day	42% 8% 14% 22% 13% 3	2600
May	1st to 10th	Day	46% 11% 14% 18% 10% 1	5897
	11th to 20th	Day	51% 10% 14% 17% 7% 1	5865
	21st to end	Day	39% 11% 14% 19% 14% 3	6447
June	1st to 10th	Day	41% 13% 16% 19% 10% 1	2600
	11th to 20th	Day	41% 13% 15% 18% 12% 2	2600
	21st to end	Day	39% 11% 17% 19% 12% 1	2600
July	1st to 10th	Day	43% 10% 17% 20% 8% 2	5835
	11th to 20th	Day	50% 10% 23% 12% 4	5831
	21st to end	Day	55% 10% 15% 14% 5% 1	6240
August	1st to 10th	Day	52% 9% 18% 17% 3	4221
	11th to 20th	Day	43% 11% 21% 16% 6% 3	4213
	21st to end	Day	34% 8% 19% 29% 9% 2	4430
September	1st to 10th	Day	38% 11% 14% 18% 16% 4	2232
	11th to 20th	Day	45% 8% 12% 19% 15% 1	2200
	21st to end	Day	50% 6% 12% 16% 14% 3	2200
October	1st to 10th	Day	29% 6% 8% 20% 26% 11%	3392
	11th to 20th	Day	23% 4 7% 23% 21% 22%	3220
	21st to end	Day	26% 4 10% 26% 17% 17%	3428
November	1st to 10th	Day	31% 5% 10% 22% 24% 7%	1942
	11th to 20th	Day	31% 5% 10% 19% 27% 7%	1800
	21st to end	Day	35% 5% 10% 22% 25% 4	1800
December	1st to 10th	Day	38% 5% 7% 19% 27% 6%	2930
	11th to 20th	Day	40% 4 12% 18% 20% 6%	3370
	21st to end	Day	41% 7% 13% 23% 12% 3	4466
January	1st to 10th	Night	30% 6% 9% 20% 24% 11%	5889
	11th to 20th	Night	31% 7% 6% 18% 26% 10%	5900
	21st to end	Night	35% 6% 7% 18% 27% 6%	6490
February	1st to 10th	Night	38% 6% 12% 22% 18% 3	2600
	11th to 20th	Night	43% 6% 10% 20% 16% 6%	2379
	21st to end	Night	41% 7% 12% 19% 15% 6%	1958
March	1st to 10th	Night	41% 7% 8% 18% 17% 9%	4918
	11th to 20th	Night	27% 6% 8% 21% 24% 14%	4980
	21st to end	Night	38% 7% 11% 24% 15% 5%	5467
April	1st to 10th	Night	36% 8% 12% 22% 18% 4	2200
	11th to 20th	Night	35% 6% 12% 22% 18% 6%	1975
	21st to end	Night	36% 7% 15% 25% 15% 2	1804
May	1st to 10th	Night	42% 11% 15% 21% 10% 1	4060
	11th to 20th	Night	48% 9% 16% 20% 7%	4033
	21st to end	Night	38% 11% 16% 23% 10% 2	4429
June	1st to 10th	Night	35% 14% 17% 23% 11% 1	1800
	11th to 20th	Night	35% 11% 19% 23% 11% 1	1800
	21st to end	Night	32% 12% 20% 22% 12% 3	1800
July	1st to 10th	Night	40% 10% 16% 24% 9% 1	4015
	11th to 20th	Night	41% 13% 25% 16% 3 1	4006
	21st to end	Night	49% 9% 20% 15% 6%	4297
August	1st to 10th	Night	48% 8% 22% 17% 6%	2904
	11th to 20th	Night	40% 7% 24% 18% 9% 1	2902
	21st to end	Night	29% 7% 18% 35% 9% 2	3421
September	1st to 10th	Night	36% 10% 17% 17% 16% 4	2163
	11th to 20th	Night	42% 8% 14% 19% 17% 1	2200
	21st to end	Night	47% 7% 11% 18% 14% 2	2200
October	1st to 10th	Night	32% 6% 8% 20% 22% 12%	3787
	11th to 20th	Night	22% 4 8% 22% 25% 18%	3876
	21st to end	Night	26% 3 9% 24% 22% 17%	4120
November	1st to 10th	Night	34% 5% 10% 20% 23% 7%	2351
	11th to 20th	Night	31% 5% 9% 21% 25% 8%	2600
	21st to end	Night	33% 5% 9% 24% 24% 5%	2600
December	1st to 10th	Night	35% 5% 10% 20% 27% 3	4250
	11th to 20th	Night	45% 4 11% 17% 17% 6%	4824
	21st to end	Night	39% 7% 17% 22% 13% 3	6490

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	36% 27% 27% 8% 2	300
	11th to 20th	Day	37% 23% 30% 9%	300
	21st to end	Day	32% 33% 26% 7% 2	330
February	1st to 10th	Day	31% 28% 25% 15% 1	300
	11th to 20th	Day	46% 25% 25% 4	300
	21st to end	Day	35% 29% 29% 7%	269
March	1st to 10th	Day	27% 23% 29% 15% 6%	500
	11th to 20th	Day	27% 27% 30% 11% 3 1	500
	21st to end	Day	30% 23% 28% 14% 4 1	550
April	1st to 10th	Day	26% 22% 29% 15% 6% 1	500
	11th to 20th	Day	22% 24% 26% 17% 9% 2	492
	21st to end	Day	21% 18% 29% 19% 8% 3	500
May	1st to 10th	Day	21% 18% 34% 16% 8% 4	503
	11th to 20th	Day	20% 14% 26% 24% 11% 5%	527
	21st to end	Day	21% 7% 24% 23% 16% 8%	573
June	1st to 10th	Day	13% 9% 27% 28% 15% 7%	530
	11th to 20th	Day	11% 7% 24% 29% 21% 9%	530
	21st to end	Day	11% 7% 25% 34% 15% 8%	530
July	1st to 10th	Day	10% 3 18% 32% 25% 12%	525
	11th to 20th	Day	8% 2 18% 31% 29% 12%	524
	21st to end	Day	12% 2 19% 30% 25% 12%	576
August	1st to 10th	Day	20% 5% 23% 24% 16% 13%	526
	11th to 20th	Day	12% 3 21% 29% 22% 13%	519
	21st to end	Day	11% 5% 16% 32% 22% 14%	583
September	1st to 10th	Day	14% 4 18% 30% 23% 12%	530
	11th to 20th	Day	18% 6% 16% 25% 25% 10%	530
	21st to end	Day	23% 10% 22% 27% 14% 5%	530
October	1st to 10th	Day	21% 8% 21% 25% 19% 6%	530
	11th to 20th	Day	16% 17% 26% 23% 16% 2	522
	21st to end	Day	20% 13% 30% 25% 9% 3	539
November	1st to 10th	Day	21% 14% 28% 24% 10% 3	480
	11th to 20th	Day	21% 26% 29% 18% 5% 1	300
	21st to end	Day	22% 22% 32% 19% 4 1	300
December	1st to 10th	Day	29% 27% 32% 10% 2	300
	11th to 20th	Day	24% 20% 36% 16% 4	300
	21st to end	Day	32% 17% 35% 11% 4 1	330
January	1st to 10th	Night	22% 23% 32% 19% 4	800
	11th to 20th	Night	23% 21% 31% 21% 3	800
	21st to end	Night	19% 23% 35% 20% 3	880
February	1st to 10th	Night	18% 19% 35% 26% 3	800
	11th to 20th	Night	27% 26% 31% 15% 1	783
	21st to end	Night	20% 22% 38% 19% 2	660
March	1st to 10th	Night	21% 21% 32% 24% 3	800
	11th to 20th	Night	24% 17% 31% 21% 6% 1	800
	21st to end	Night	21% 18% 33% 22% 6%	880
April	1st to 10th	Night	20% 20% 29% 24% 7%	800
	11th to 20th	Night	19% 19% 26% 25% 10% 1	791
	21st to end	Night	18% 11% 29% 32% 10%	604
May	1st to 10th	Night	18% 10% 30% 29% 14%	600
	11th to 20th	Night	19% 8% 20% 33% 17% 3	591
	21st to end	Night	21% 4 16% 28% 27% 5%	650
June	1st to 10th	Night	12% 4 18% 34% 29% 4	600
	11th to 20th	Night	13% 3 18% 30% 32% 5%	600
	21st to end	Night	9% 2 13% 38% 35% 4	600
July	1st to 10th	Night	12% 3 9% 29% 42% 6%	585
	11th to 20th	Night	8% 2 8% 31% 45% 7%	582
	21st to end	Night	7% 2 9% 33% 40% 7%	657
August	1st to 10th	Night	17% 2 12% 30% 35% 5%	597
	11th to 20th	Night	16% 3 11% 28% 34% 8%	594
	21st to end	Night	14% 2 10% 29% 36% 9%	780
September	1st to 10th	Night	13% 4 14% 29% 34% 7%	800
	11th to 20th	Night	19% 3 13% 29% 31% 6%	800
	21st to end	Night	26% 5% 16% 29% 22% 2	800
October	1st to 10th	Night	18% 9% 21% 23% 23% 6%	800
	11th to 20th	Night	19% 10% 24% 29% 15% 2	793
	21st to end	Night	18% 12% 21% 33% 14% 2	836
November	1st to 10th	Night	18% 11% 24% 31% 13% 3	780
	11th to 20th	Night	18% 14% 26% 32% 9% 1	800
	21st to end	Night	18% 17% 26% 28% 10% 1	800
December	1st to 10th	Night	22% 19% 29% 24% 6%	800
	11th to 20th	Night	20% 15% 33% 25% 6% 1	800
	21st to end	Night	27% 17% 24% 27% 5%	880

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