Beckwith Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Beckwith Park clear sky chart from 2005-11-06 to 2025-09-04.

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	16% 10% 3 8% 5% 5% 4 4 5% 6% 32%	126538
	Night	16% 12% 4 9% 5% 4 4 3 5% 6% 31%	122175
Transparency	Day	51% 6% 11% 21% 10% 1	130016
	Night	53% 6% 11% 19% 10% 1	126771
Seeing	Day	23% 17% 30% 20% 8% 2	15515
	Night	23% 14% 30% 24% 9% 1	24574

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	13% 17% 6% 13% 8% 6% 4 3 4 5% 21%	3597
	11th to 20th	Day	12% 16% 7% 12% 7% 6% 5% 3 5% 5% 22%	3570
	21st to end	Day	12% 18% 7% 15% 7% 6% 4 3 5% 5% 19%	4206
February	1st to 10th	Day	15% 15% 5% 13% 7% 5% 4 3 5% 5% 23%	1800
	11th to 20th	Day	13% 14% 5% 11% 7% 5% 4 3 5% 5% 28%	1753
	21st to end	Day	19% 14% 4 9% 6% 5% 5% 4 5% 5% 24%	1645
March	1st to 10th	Day	18% 14% 5% 11% 5% 4 4 3 4 6% 26%	4518
	11th to 20th	Day	10% 12% 4 9% 6% 5% 5% 4 6% 7% 30%	4980
	21st to end	Day	17% 11% 4 8% 5% 4 3 3 4 4 38%	5736
April	1st to 10th	Day	21% 12% 3 8% 5% 4 4 3 4 6% 32%	2400
	11th to 20th	Day	22% 10% 3 7% 4 4 3 3 3 5% 36%	2374
	21st to end	Day	23% 9% 3 8% 5% 3 4 3 4 6% 32%	2525
May	1st to 10th	Day	23% 11% 3 8% 4 4 4 4 5% 6% 27%	6346
	11th to 20th	Day	16% 10% 3 9% 5% 5% 5% 4 5% 7% 31%	6318
	21st to end	Day	19% 9% 3 7% 4 4 5% 3 5% 7% 34%	6949
June	1st to 10th	Day	20% 10% 2 7% 5% 5% 5% 4 5% 6% 31%	2800
	11th to 20th	Day	14% 6% 2 7% 5% 4 5% 5% 7% 8% 38%	2800
	21st to end	Day	17% 7% 3 7% 6% 5% 5% 4 7% 7% 33%	2800
July	1st to 10th	Day	13% 6% 3 7% 5% 5% 5% 5% 7% 8% 35%	6360
	11th to 20th	Day	10% 5% 2 7% 5% 5% 5% 4 7% 8% 42%	6360
	21st to end	Day	9% 5% 2 5% 4 5% 4 4 7% 10% 45%	6926
August	1st to 10th	Day	14% 8% 3 7% 5% 5% 4 4 5% 8% 36%	4441
	11th to 20th	Day	16% 7% 3 6% 4 4 4 4 6% 8% 38%	4141
	21st to end	Day	14% 6% 2 6% 4 5% 5% 4 7% 9% 38%	4312
September	1st to 10th	Day	13% 6% 2 6% 5% 5% 4 5% 6% 7% 41%	2316
	11th to 20th	Day	12% 5% 2 6% 4 4 5% 3 6% 7% 47%	2280
	21st to end	Day	17% 6% 2 6% 5% 4 4 4 5% 7% 39%	2022
October	1st to 10th	Day	20% 9% 2 7% 4 4 4 4 4 6% 36%	1900
	11th to 20th	Day	20% 10% 3 8% 6% 5% 5% 4 4 6% 29%	1900
	21st to end	Day	25% 11% 3 8% 5% 3 5% 3 4 6% 27%	1956
November	1st to 10th	Day	15% 9% 3 8% 5% 5% 6% 4 5% 6% 33%	1761
	11th to 20th	Day	16% 13% 3 10% 6% 4 5% 4 4 6% 29%	1600
	21st to end	Day	20% 15% 4 11% 6% 6% 5% 4 5% 5% 20%	1600
December	1st to 10th	Day	21% 20% 6% 11% 5% 5% 4 4 5% 5% 15%	2600
	11th to 20th	Day	17% 17% 6% 11% 6% 5% 3 3 4 4 24%	2986
	21st to end	Day	22% 16% 5% 13% 6% 4 4 3 3 4 21%	3960
January	1st to 10th	Night	14% 19% 8% 13% 6% 5% 4 3 4 5% 21%	6349
	11th to 20th	Night	11% 15% 6% 15% 8% 6% 5% 3 4 5% 20%	6315
	21st to end	Night	14% 17% 7% 12% 7% 6% 4 3 4 5% 20%	6748
February	1st to 10th	Night	13% 16% 4 12% 8% 5% 5% 3 5% 5% 23%	2600
	11th to 20th	Night	13% 13% 5% 11% 7% 5% 5% 3 4 5% 28%	2533
	21st to end	Night	14% 14% 4 10% 7% 5% 5% 3 5% 6% 28%	1984
March	1st to 10th	Night	22% 13% 4 9% 5% 5% 4 2 3 4 28%	5318
	11th to 20th	Night	12% 12% 4 8% 5% 4 5% 4 7% 8% 31%	4979
	21st to end	Night	18% 10% 4 8% 5% 4 4 3 4 6% 34%	5195
April	1st to 10th	Night	19% 11% 3 8% 5% 4 4 3 5% 5% 33%	2000
	11th to 20th	Night	19% 9% 3 9% 5% 4 3 2 3 5% 37%	1975
	21st to end	Night	20% 11% 3 7% 6% 3 4 3 4 6% 34%	1888
May	1st to 10th	Night	23% 10% 4 7% 5% 4 5% 5% 6% 6% 25%	3594
	11th to 20th	Night	15% 7% 2 7% 5% 5% 4 3 5% 7% 40%	3575
	21st to end	Night	17% 9% 3 7% 4 4 5% 4 5% 7% 33%	3926
June	1st to 10th	Night	17% 7% 2 8% 6% 4 5% 4 6% 8% 34%	1600
	11th to 20th	Night	14% 6% 3 7% 5% 3 4 4 5% 7% 43%	1600
	21st to end	Night	16% 8% 3 7% 5% 4 5% 4 6% 7% 36%	1600
July	1st to 10th	Night	12% 7% 3 8% 5% 5% 5% 4 7% 10% 34%	3600
	11th to 20th	Night	12% 6% 2 6% 4 4 4 4 6% 8% 45%	3600
	21st to end	Night	8% 6% 2 6% 4 5% 5% 4 6% 8% 46%	3926
August	1st to 10th	Night	11% 7% 2 8% 4 4 4 4 6% 9% 42%	2706
	11th to 20th	Night	12% 8% 3 6% 4 4 4 3 5% 7% 44%	2875
	21st to end	Night	10% 6% 2 6% 5% 5% 5% 4 6% 8% 42%	3586
September	1st to 10th	Night	11% 5% 2 7% 5% 3 4 3 4 6% 48%	1931
	11th to 20th	Night	14% 4 2 5% 3 3 4 3 5% 7% 50%	1900
	21st to end	Night	16% 6% 2 5% 4 4 4 3 4 7% 43%	2153
October	1st to 10th	Night	17% 9% 3 6% 4 3 4 3 5% 7% 38%	2280
	11th to 20th	Night	20% 9% 3 6% 5% 5% 5% 4 5% 6% 32%	2280
	21st to end	Night	22% 10% 4 8% 4 4 4 4 5% 6% 29%	2641
November	1st to 10th	Night	19% 11% 3 6% 4 4 4 3 5% 5% 35%	2537
	11th to 20th	Night	17% 11% 3 8% 5% 4 6% 3 5% 6% 31%	2797
	21st to end	Night	20% 14% 3 9% 6% 5% 4 3 5% 6% 24%	2800
December	1st to 10th	Night	19% 17% 5% 12% 6% 6% 5% 4 5% 5% 17%	4580
	11th to 20th	Night	22% 15% 5% 10% 6% 4 3 3 3 4 26%	5208
	21st to end	Night	26% 17% 4 11% 4 4 3 3 4 4 20%	6996

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	65% 5% 10% 13% 5% 1	3598
	11th to 20th	Day	64% 5% 10% 12% 8% 1	3600
	21st to end	Day	66% 6% 9% 10% 8% 1	4206
February	1st to 10th	Day	63% 6% 7% 18% 5% 1	1800
	11th to 20th	Day	59% 5% 10% 17% 9% 1	1762
	21st to end	Day	62% 5% 10% 12% 9% 1	1645
March	1st to 10th	Day	60% 4 9% 13% 12% 2	4521
	11th to 20th	Day	51% 6% 15% 15% 10% 1	4980
	21st to end	Day	50% 4 5% 19% 19% 3	5736
April	1st to 10th	Day	54% 4 6% 18% 14% 3	2400
	11th to 20th	Day	52% 4 7% 20% 16% 2	2374
	21st to end	Day	54% 5% 7% 15% 14% 4	2525
May	1st to 10th	Day	58% 6% 7% 18% 9% 2	6357
	11th to 20th	Day	51% 8% 11% 18% 11% 1	6322
	21st to end	Day	49% 6% 11% 22% 11% 1	6949
June	1st to 10th	Day	52% 6% 9% 19% 12% 1	2800
	11th to 20th	Day	41% 9% 10% 25% 13% 2	2800
	21st to end	Day	49% 8% 11% 19% 11% 1	2800
July	1st to 10th	Day	42% 8% 13% 26% 10%	6290
	11th to 20th	Day	36% 8% 13% 28% 14%	6285
	21st to end	Day	33% 7% 13% 36% 10%	6728
August	1st to 10th	Day	46% 7% 13% 24% 9% 1	4427
	11th to 20th	Day	42% 6% 13% 29% 9% 1	4180
	21st to end	Day	40% 7% 15% 27% 11%	4312
September	1st to 10th	Day	40% 7% 13% 28% 11%	2316
	11th to 20th	Day	35% 7% 12% 31% 14%	2280
	21st to end	Day	43% 6% 14% 26% 10%	2022
October	1st to 10th	Day	46% 5% 11% 30% 7%	3160
	11th to 20th	Day	46% 5% 14% 24% 10%	3140
	21st to end	Day	49% 5% 17% 22% 7%	3194
November	1st to 10th	Day	49% 7% 13% 23% 7% 1	1761
	11th to 20th	Day	56% 5% 13% 15% 10% 1	1600
	21st to end	Day	64% 8% 12% 10% 6%	1600
December	1st to 10th	Day	71% 7% 11% 9% 2	2600
	11th to 20th	Day	65% 6% 10% 13% 6%	2986
	21st to end	Day	68% 5% 7% 15% 5%	3960
January	1st to 10th	Night	67% 5% 11% 13% 5%	6349
	11th to 20th	Night	65% 6% 11% 12% 6%	6360
	21st to end	Night	66% 6% 8% 10% 11% 1	6748
February	1st to 10th	Night	62% 5% 10% 16% 6% 1	2600
	11th to 20th	Night	59% 5% 10% 19% 8% 1	2535
	21st to end	Night	57% 5% 9% 19% 9% 1	1984
March	1st to 10th	Night	60% 4 7% 16% 11% 3	5328
	11th to 20th	Night	49% 7% 17% 16% 8% 3	4980
	21st to end	Night	51% 5% 6% 22% 13% 2	5195
April	1st to 10th	Night	53% 5% 7% 19% 14% 2	2000
	11th to 20th	Night	52% 4 6% 20% 17% 1	1975
	21st to end	Night	52% 6% 6% 17% 16% 3	1888
May	1st to 10th	Night	57% 7% 8% 17% 8% 3	3600
	11th to 20th	Night	42% 8% 13% 21% 14% 1	3576
	21st to end	Night	47% 7% 12% 18% 14% 1	3927
June	1st to 10th	Night	47% 8% 11% 22% 11% 1	1600
	11th to 20th	Night	40% 6% 12% 23% 17% 2	1600
	21st to end	Night	46% 8% 11% 21% 13% 1	1600
July	1st to 10th	Night	42% 8% 17% 18% 14% 1	3560
	11th to 20th	Night	36% 6% 13% 31% 13%	3552
	21st to end	Night	34% 8% 13% 30% 15% 1	3809
August	1st to 10th	Night	38% 8% 14% 26% 13% 1	2696
	11th to 20th	Night	39% 7% 16% 29% 9% 1	2902
	21st to end	Night	37% 8% 15% 27% 11% 1	3586
September	1st to 10th	Night	38% 7% 10% 30% 14% 1	1931
	11th to 20th	Night	32% 7% 13% 35% 11% 1	1900
	21st to end	Night	40% 6% 12% 29% 11% 1	2153
October	1st to 10th	Night	40% 6% 11% 30% 12%	3800
	11th to 20th	Night	43% 6% 15% 26% 10%	3779
	21st to end	Night	48% 6% 17% 21% 8%	4340
November	1st to 10th	Night	50% 5% 13% 22% 9% 1	2537
	11th to 20th	Night	54% 6% 11% 18% 10% 1	2797
	21st to end	Night	61% 6% 12% 16% 5%	2800
December	1st to 10th	Night	68% 7% 12% 11% 3	4580
	11th to 20th	Night	63% 5% 7% 14% 10% 1	5208
	21st to end	Night	69% 4 6% 13% 9%	6996

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	21% 25% 35% 15% 5%	200
	11th to 20th	Day	28% 20% 35% 15% 3 1	200
	21st to end	Day	25% 21% 35% 15% 3	273
February	1st to 10th	Day	31% 27% 27% 13% 1	300
	11th to 20th	Day	27% 30% 35% 7% 1	300
	21st to end	Day	31% 21% 36% 11% 1	409
March	1st to 10th	Day	27% 22% 31% 16% 3	500
	11th to 20th	Day	28% 21% 32% 16% 3	500
	21st to end	Day	31% 23% 28% 13% 5% 1	550
April	1st to 10th	Day	32% 22% 27% 13% 5% 1	500
	11th to 20th	Day	36% 18% 22% 14% 8% 2	492
	21st to end	Day	32% 20% 28% 13% 6% 2	500
May	1st to 10th	Day	27% 15% 32% 19% 5% 2	503
	11th to 20th	Day	20% 18% 33% 21% 7% 2	527
	21st to end	Day	21% 16% 32% 20% 9% 2	573
June	1st to 10th	Day	24% 14% 33% 20% 8% 1	530
	11th to 20th	Day	17% 16% 33% 22% 10% 2	530
	21st to end	Day	22% 14% 34% 18% 11% 2	530
July	1st to 10th	Day	13% 7% 31% 32% 14% 2	525
	11th to 20th	Day	12% 11% 33% 28% 13% 3	524
	21st to end	Day	13% 10% 33% 29% 11% 3	576
August	1st to 10th	Day	14% 9% 29% 32% 13% 3	526
	11th to 20th	Day	15% 8% 26% 29% 16% 6%	519
	21st to end	Day	14% 12% 31% 25% 11% 7%	583
September	1st to 10th	Day	16% 13% 27% 25% 11% 8%	502
	11th to 20th	Day	12% 10% 25% 23% 18% 12%	490
	21st to end	Day	19% 13% 29% 22% 13% 4	490
October	1st to 10th	Day	25% 15% 25% 19% 12% 4	490
	11th to 20th	Day	27% 20% 29% 17% 6% 2	490
	21st to end	Day	31% 18% 28% 19% 4	468
November	1st to 10th	Day	27% 19% 29% 18% 6% 1	395
	11th to 20th	Day	26% 26% 28% 13% 7% 1	200
	21st to end	Day	34% 21% 33% 9% 4	200
December	1st to 10th	Day	32% 16% 35% 15% 3	200
	11th to 20th	Day	32% 28% 28% 10% 3	200
	21st to end	Day	31% 20% 27% 17% 3 1	220
January	1st to 10th	Night	27% 20% 33% 16% 4	800
	11th to 20th	Night	29% 18% 29% 19% 4 1	800
	21st to end	Night	21% 16% 35% 24% 5%	880
February	1st to 10th	Night	23% 22% 33% 19% 3	800
	11th to 20th	Night	22% 19% 40% 16% 3	783
	21st to end	Night	24% 22% 31% 19% 4	660
March	1st to 10th	Night	25% 15% 35% 21% 4	800
	11th to 20th	Night	24% 22% 29% 20% 5%	800
	21st to end	Night	25% 15% 30% 23% 7% 1	880
April	1st to 10th	Night	27% 15% 32% 22% 4	800
	11th to 20th	Night	27% 18% 28% 19% 7% 1	791
	21st to end	Night	27% 13% 29% 23% 7% 1	688
May	1st to 10th	Night	24% 10% 29% 27% 9% 1	400
	11th to 20th	Night	21% 10% 34% 28% 7%	394
	21st to end	Night	16% 7% 37% 28% 11%	433
June	1st to 10th	Night	19% 7% 33% 34% 8%	400
	11th to 20th	Night	18% 8% 30% 31% 12% 1	400
	21st to end	Night	19% 8% 32% 29% 12%	400
July	1st to 10th	Night	8% 7% 32% 39% 13% 1	390
	11th to 20th	Night	13% 5% 27% 40% 13% 1	388
	21st to end	Night	10% 4 30% 43% 13% 1	438
August	1st to 10th	Night	10% 5% 27% 39% 19% 1	466
	11th to 20th	Night	11% 4 24% 34% 25% 2	594
	21st to end	Night	13% 7% 29% 32% 17% 2	880
September	1st to 10th	Night	15% 6% 32% 29% 17% 1	773
	11th to 20th	Night	18% 7% 22% 28% 22% 4	760
	21st to end	Night	18% 10% 26% 24% 20% 2	760
October	1st to 10th	Night	20% 12% 28% 24% 15% 2	760
	11th to 20th	Night	25% 14% 29% 23% 9% 1	760
	21st to end	Night	27% 17% 26% 25% 6%	836
November	1st to 10th	Night	28% 14% 29% 21% 7% 1	780
	11th to 20th	Night	25% 15% 33% 18% 8% 1	800
	21st to end	Night	31% 18% 27% 18% 6% 1	800
December	1st to 10th	Night	30% 18% 31% 19% 3	800
	11th to 20th	Night	29% 18% 30% 19% 4 1	800
	21st to end	Night	35% 16% 28% 18% 3	880

Page generated at 2025-09-01 01:51:05. Version ac07

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