High Point
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the High Point clear sky chart from 2005-11-06 to 2026-04-02.

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	13% 6% 2 6% 4 4 4 4 6% 8% 43%	131650
	Night	14% 6% 2 6% 4 4 4 3 5% 7% 45%	130178
Transparency	Day	37% 7% 12% 20% 18% 5%	135256
	Night	37% 6% 10% 20% 20% 6%	134629
Seeing	Day	16% 9% 24% 24% 18% 9%	17228
	Night	16% 8% 25% 31% 18% 2	27389

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	16% 6% 2 5% 3 2 3 3 3 4 52%	5258
	11th to 20th	Day	11% 6% 2 4 3 2 3 2 3 4 60%	5280
	21st to end	Day	17% 8% 3 6% 3 3 3 3 4 4 45%	5780
February	1st to 10th	Day	14% 6% 2 7% 4 4 4 4 6% 7% 42%	1890
	11th to 20th	Day	20% 8% 2 4 4 3 3 3 4 5% 44%	1922
	21st to end	Day	18% 7% 3 6% 4 3 4 3 4 6% 41%	1835
March	1st to 10th	Day	19% 7% 2 6% 4 3 3 3 5% 7% 41%	5045
	11th to 20th	Day	9% 4 2 5% 3 3 4 3 5% 7% 54%	5090
	21st to end	Day	16% 7% 2 5% 4 4 4 3 4 5% 47%	5586
April	1st to 10th	Day	11% 5% 2 4 3 3 3 3 7% 7% 53%	2271
	11th to 20th	Day	12% 4 2 6% 4 4 3 3 5% 7% 50%	2374
	21st to end	Day	13% 5% 2 5% 5% 4 5% 4 5% 8% 45%	2485
May	1st to 10th	Day	9% 7% 3 7% 5% 5% 6% 5% 8% 11% 34%	5862
	11th to 20th	Day	20% 8% 3 7% 5% 5% 5% 5% 6% 8% 30%	5861
	21st to end	Day	12% 5% 2 6% 5% 4 5% 4 6% 9% 42%	6433
June	1st to 10th	Day	9% 6% 2 6% 5% 4 5% 5% 8% 10% 41%	2600
	11th to 20th	Day	8% 5% 2 5% 4 4 5% 5% 7% 11% 43%	2600
	21st to end	Day	6% 5% 2 6% 5% 4 6% 6% 8% 10% 43%	2600
July	1st to 10th	Day	9% 5% 2 7% 5% 6% 6% 5% 8% 10% 37%	5900
	11th to 20th	Day	6% 6% 3 7% 6% 6% 7% 6% 10% 14% 29%	5900
	21st to end	Day	9% 7% 3 8% 6% 6% 6% 5% 8% 10% 32%	6424
August	1st to 10th	Day	18% 8% 3 7% 5% 5% 6% 5% 7% 9% 25%	4234
	11th to 20th	Day	8% 6% 2 8% 6% 6% 6% 6% 8% 10% 34%	4159
	21st to end	Day	6% 4 1 5% 4 4 4 4 6% 9% 52%	4312
September	1st to 10th	Day	9% 5% 2 6% 5% 5% 5% 4 5% 7% 48%	2346
	11th to 20th	Day	12% 7% 2 6% 4 4 5% 4 6% 8% 44%	2200
	21st to end	Day	20% 7% 2 7% 5% 4 4 3 5% 6% 39%	2200
October	1st to 10th	Day	13% 5% 2 5% 3 3 3 3 4 6% 53%	2018
	11th to 20th	Day	13% 4 2 5% 3 2 3 2 4 5% 57%	2000
	21st to end	Day	12% 5% 2 5% 3 3 2 3 4 5% 56%	2200
November	1st to 10th	Day	13% 5% 2 4 3 3 3 3 4 5% 55%	2057
	11th to 20th	Day	13% 4 2 5% 4 2 3 3 5% 6% 53%	1990
	21st to end	Day	13% 5% 2 6% 4 4 4 3 5% 5% 50%	1890
December	1st to 10th	Day	13% 6% 2 4 3 3 3 3 4 6% 53%	3020
	11th to 20th	Day	16% 7% 2 7% 3 3 4 3 5% 6% 44%	3463
	21st to end	Day	19% 7% 2 5% 3 3 4 3 5% 7% 43%	4565
January	1st to 10th	Night	13% 6% 2 5% 3 3 3 3 4 5% 54%	7635
	11th to 20th	Night	12% 6% 2 5% 3 2 3 2 3 4 58%	7680
	21st to end	Night	17% 8% 2 5% 4 3 3 3 5% 5% 46%	8401
February	1st to 10th	Night	16% 6% 2 5% 4 4 4 3 5% 6% 46%	2730
	11th to 20th	Night	21% 6% 2 4 4 4 4 3 4 5% 44%	2579
	21st to end	Night	15% 7% 3 5% 3 4 4 4 4 7% 45%	1969
March	1st to 10th	Night	17% 7% 2 6% 4 4 3 3 4 5% 45%	5028
	11th to 20th	Night	10% 5% 2 5% 3 3 3 3 5% 6% 56%	5090
	21st to end	Night	14% 5% 2 5% 3 4 4 3 5% 7% 48%	5588
April	1st to 10th	Night	13% 5% 2 5% 3 4 4 3 5% 7% 49%	2151
	11th to 20th	Night	12% 6% 2 5% 4 3 4 4 5% 6% 50%	1975
	21st to end	Night	13% 5% 2 5% 4 4 4 3 6% 7% 47%	1930
May	1st to 10th	Night	13% 7% 3 7% 6% 4 5% 4 6% 8% 38%	4033
	11th to 20th	Night	18% 7% 3 7% 4 3 5% 4 5% 9% 35%	4032
	21st to end	Night	15% 6% 2 5% 3 4 4 3 5% 10% 43%	4421
June	1st to 10th	Night	9% 5% 3 5% 5% 6% 5% 5% 7% 10% 39%	1800
	11th to 20th	Night	10% 6% 2 5% 5% 4 5% 5% 7% 11% 41%	1800
	21st to end	Night	7% 5% 2 5% 6% 5% 6% 5% 8% 12% 40%	1800
July	1st to 10th	Night	10% 7% 2 9% 6% 5% 6% 5% 8% 10% 32%	4058
	11th to 20th	Night	10% 7% 3 9% 6% 7% 7% 6% 8% 10% 26%	4057
	21st to end	Night	12% 8% 3 7% 5% 6% 6% 5% 8% 11% 30%	4427
August	1st to 10th	Night	20% 9% 3 8% 5% 6% 6% 5% 7% 8% 23%	2915
	11th to 20th	Night	9% 6% 2 7% 5% 5% 5% 5% 8% 11% 38%	2875
	21st to end	Night	6% 5% 2 6% 4 4 4 4 6% 9% 50%	3553
September	1st to 10th	Night	8% 7% 2 5% 4 4 5% 4 6% 8% 47%	2050
	11th to 20th	Night	14% 7% 2 6% 4 5% 4 4 5% 7% 44%	2200
	21st to end	Night	18% 7% 2 7% 5% 4 5% 4 5% 6% 37%	2200
October	1st to 10th	Night	13% 6% 3 7% 3 3 3 3 4 6% 50%	2380
	11th to 20th	Night	13% 5% 1 4 3 3 3 3 4 5% 56%	2400
	21st to end	Night	12% 6% 2 5% 3 3 3 2 3 4 57%	2640
November	1st to 10th	Night	13% 6% 2 5% 3 3 3 3 3 4 54%	2461
	11th to 20th	Night	12% 5% 2 4 4 4 4 3 4 5% 52%	2625
	21st to end	Night	14% 5% 1 4 2 3 4 4 5% 7% 51%	2730
December	1st to 10th	Night	14% 6% 2 6% 4 3 3 2 3 5% 53%	4380
	11th to 20th	Night	19% 7% 3 7% 4 4 4 3 4 5% 41%	4952
	21st to end	Night	19% 5% 2 4 3 3 3 3 5% 7% 47%	6633

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	37% 3 8% 20% 27% 5%	5259
	11th to 20th	Day	29% 4 4 14% 36% 13%	5280
	21st to end	Day	43% 3 5% 21% 20% 7%	5780
February	1st to 10th	Day	39% 5% 11% 20% 20% 5%	1890
	11th to 20th	Day	42% 5% 8% 21% 18% 6%	1931
	21st to end	Day	44% 5% 10% 15% 20% 6%	1835
March	1st to 10th	Day	42% 5% 7% 17% 18% 11%	5045
	11th to 20th	Day	29% 5% 8% 18% 22% 17%	5090
	21st to end	Day	40% 5% 8% 22% 20% 6%	5586
April	1st to 10th	Day	29% 5% 13% 23% 24% 6%	2271
	11th to 20th	Day	34% 5% 11% 22% 20% 8%	2374
	21st to end	Day	37% 7% 12% 24% 16% 3	2485
May	1st to 10th	Day	40% 11% 17% 20% 11% 2	5897
	11th to 20th	Day	50% 9% 12% 19% 9% 1	5865
	21st to end	Day	36% 9% 13% 21% 18% 3	6447
June	1st to 10th	Day	35% 10% 17% 23% 14% 1	2600
	11th to 20th	Day	33% 10% 19% 21% 15% 2	2600
	21st to end	Day	32% 12% 18% 23% 14% 1	2600
July	1st to 10th	Day	38% 11% 17% 20% 12% 2	5835
	11th to 20th	Day	38% 15% 27% 16% 4	5831
	21st to end	Day	42% 12% 16% 21% 8%	6240
August	1st to 10th	Day	51% 11% 17% 17% 4	4221
	11th to 20th	Day	39% 12% 20% 19% 8% 1	4198
	21st to end	Day	26% 9% 15% 34% 15% 2	4312
September	1st to 10th	Day	34% 9% 13% 21% 19% 4	2346
	11th to 20th	Day	38% 8% 11% 20% 20% 3	2200
	21st to end	Day	45% 6% 10% 19% 16% 3	2200
October	1st to 10th	Day	30% 5% 8% 19% 27% 10%	3278
	11th to 20th	Day	21% 3 5% 21% 25% 25%	3240
	21st to end	Day	24% 4 9% 24% 23% 16%	3538
November	1st to 10th	Day	32% 4 7% 22% 27% 8%	2057
	11th to 20th	Day	31% 4 8% 24% 27% 6%	1990
	21st to end	Day	36% 4 8% 22% 26% 4	1890
December	1st to 10th	Day	34% 4 7% 20% 28% 7%	3020
	11th to 20th	Day	42% 4 10% 16% 23% 6%	3460
	21st to end	Day	39% 5% 11% 27% 17% 1	4565
January	1st to 10th	Night	32% 4 10% 21% 25% 8%	7636
	11th to 20th	Night	32% 3 4 16% 35% 10%	7680
	21st to end	Night	41% 3 6% 20% 24% 7%	8401
February	1st to 10th	Night	39% 4 10% 22% 21% 5%	2730
	11th to 20th	Night	43% 4 8% 17% 21% 7%	2581
	21st to end	Night	40% 5% 9% 18% 21% 7%	1969
March	1st to 10th	Night	41% 5% 6% 15% 23% 9%	5028
	11th to 20th	Night	29% 4 6% 17% 26% 18%	5090
	21st to end	Night	36% 5% 8% 25% 22% 5%	5588
April	1st to 10th	Night	35% 5% 11% 19% 24% 6%	2151
	11th to 20th	Night	33% 5% 10% 21% 22% 8%	1975
	21st to end	Night	36% 6% 13% 24% 17% 4	1930
May	1st to 10th	Night	42% 8% 15% 19% 14% 1	4060
	11th to 20th	Night	45% 9% 14% 18% 13% 1	4033
	21st to end	Night	35% 8% 13% 27% 14% 3	4429
June	1st to 10th	Night	36% 12% 16% 21% 14% 2	1800
	11th to 20th	Night	36% 10% 18% 20% 14% 2	1800
	21st to end	Night	33% 12% 18% 21% 13% 3	1800
July	1st to 10th	Night	44% 12% 15% 16% 12% 1	4015
	11th to 20th	Night	48% 16% 19% 11% 3 1	4006
	21st to end	Night	44% 11% 17% 20% 7%	4297
August	1st to 10th	Night	54% 11% 16% 13% 5% 1	2904
	11th to 20th	Night	35% 11% 22% 22% 9% 1	2902
	21st to end	Night	29% 9% 13% 30% 17% 2	3553
September	1st to 10th	Night	33% 9% 15% 21% 17% 6%	2050
	11th to 20th	Night	39% 9% 11% 17% 21% 2	2200
	21st to end	Night	46% 8% 11% 17% 15% 4	2200
October	1st to 10th	Night	37% 5% 8% 18% 25% 7%	3887
	11th to 20th	Night	23% 3 6% 22% 27% 18%	3899
	21st to end	Night	25% 3 6% 24% 24% 17%	4252
November	1st to 10th	Night	34% 5% 7% 20% 24% 9%	2461
	11th to 20th	Night	34% 5% 7% 17% 27% 10%	2625
	21st to end	Night	33% 4 7% 24% 26% 6%	2730
December	1st to 10th	Night	35% 4 6% 21% 29% 5%	4380
	11th to 20th	Night	46% 5% 8% 16% 16% 8%	4954
	21st to end	Night	37% 4 13% 23% 21% 2	6633

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	22% 18% 38% 18% 4	330
	11th to 20th	Day	21% 24% 35% 15% 5%	330
	21st to end	Day	20% 20% 40% 16% 4	363
February	1st to 10th	Day	18% 15% 42% 17% 6%	330
	11th to 20th	Day	33% 20% 33% 9% 5%	330
	21st to end	Day	24% 21% 31% 19% 5%	378
March	1st to 10th	Day	21% 13% 33% 25% 8%	540
	11th to 20th	Day	19% 16% 41% 19% 4 1	540
	21st to end	Day	20% 14% 38% 21% 6% 1	594
April	1st to 10th	Day	20% 16% 31% 21% 10% 2	504
	11th to 20th	Day	14% 15% 30% 23% 14% 3	492
	21st to end	Day	19% 9% 27% 27% 16% 2	500
May	1st to 10th	Day	13% 14% 31% 23% 13% 5%	503
	11th to 20th	Day	16% 8% 22% 26% 20% 8%	527
	21st to end	Day	16% 5% 19% 24% 22% 14%	573
June	1st to 10th	Day	12% 3 19% 31% 26% 10%	530
	11th to 20th	Day	9% 3 18% 27% 25% 18%	530
	21st to end	Day	8% 3 12% 32% 33% 12%	530
July	1st to 10th	Day	9% 1 10% 24% 35% 20%	525
	11th to 20th	Day	5% 1 10% 26% 34% 23%	524
	21st to end	Day	7% 3 9% 26% 34% 20%	576
August	1st to 10th	Day	15% 3 14% 24% 29% 15%	526
	11th to 20th	Day	9% 3 9% 29% 31% 19%	519
	21st to end	Day	9% 2 12% 25% 28% 24%	583
September	1st to 10th	Day	12% 2 14% 25% 29% 19%	530
	11th to 20th	Day	15% 3 13% 26% 26% 17%	530
	21st to end	Day	23% 5% 20% 27% 19% 5%	530
October	1st to 10th	Day	17% 6% 18% 27% 21% 11%	530
	11th to 20th	Day	12% 9% 24% 29% 21% 5%	530
	21st to end	Day	14% 11% 23% 28% 18% 5%	583
November	1st to 10th	Day	17% 9% 30% 26% 13% 5%	535
	11th to 20th	Day	15% 14% 32% 24% 11% 3	430
	21st to end	Day	13% 17% 32% 22% 13% 3	330
December	1st to 10th	Day	21% 15% 37% 22% 5% 1	330
	11th to 20th	Day	18% 13% 32% 27% 10%	330
	21st to end	Day	24% 17% 29% 21% 9% 1	363
January	1st to 10th	Night	20% 15% 35% 24% 5%	840
	11th to 20th	Night	19% 12% 38% 27% 4	840
	21st to end	Night	18% 12% 41% 26% 2	924
February	1st to 10th	Night	19% 12% 37% 29% 3	840
	11th to 20th	Night	26% 16% 37% 21% 1	823
	21st to end	Night	18% 17% 35% 26% 4	692
March	1st to 10th	Night	17% 13% 35% 30% 4	840
	11th to 20th	Night	18% 13% 36% 26% 7%	840
	21st to end	Night	17% 12% 36% 30% 5%	924
April	1st to 10th	Night	15% 15% 33% 30% 7%	805
	11th to 20th	Night	15% 11% 34% 28% 12% 1	791
	21st to end	Night	14% 7% 30% 38% 11%	730
May	1st to 10th	Night	12% 10% 29% 35% 14%	600
	11th to 20th	Night	13% 7% 22% 36% 20% 2	591
	21st to end	Night	15% 3 15% 34% 31% 3	650
June	1st to 10th	Night	10% 3 17% 39% 28% 2	600
	11th to 20th	Night	11% 3 14% 34% 33% 6%	600
	21st to end	Night	9% 1 11% 37% 40% 2	600
July	1st to 10th	Night	10% 1 9% 29% 44% 6%	585
	11th to 20th	Night	6% 2 7% 31% 46% 8%	582
	21st to end	Night	9% 2 8% 36% 39% 7%	657
August	1st to 10th	Night	15% 3 8% 33% 37% 6%	597
	11th to 20th	Night	11% 2 9% 32% 38% 7%	594
	21st to end	Night	11% 3 9% 30% 39% 8%	860
September	1st to 10th	Night	11% 2 10% 34% 36% 7%	800
	11th to 20th	Night	15% 4 12% 30% 34% 6%	800
	21st to end	Night	21% 4 17% 32% 24% 2	800
October	1st to 10th	Night	16% 5% 18% 31% 26% 5%	800
	11th to 20th	Night	16% 7% 25% 33% 18% 3	800
	21st to end	Night	15% 8% 25% 33% 18% 2	880
November	1st to 10th	Night	15% 9% 24% 35% 15% 1	820
	11th to 20th	Night	15% 11% 30% 33% 10%	840
	21st to end	Night	16% 8% 31% 32% 12% 1	840
December	1st to 10th	Night	20% 9% 34% 29% 7%	840
	11th to 20th	Night	20% 7% 34% 31% 8%	840
	21st to end	Night	23% 10% 27% 32% 7%	924

Page generated at 2026-03-30 02:18:45. Version ac07

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