Pinhey's Point
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Pinhey's Point 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	16% 10% 3 8% 5% 5% 5% 4 5% 7% 32%	127022
	Night	17% 12% 4 9% 5% 5% 4 3 5% 6% 30%	122669
Transparency	Day	51% 5% 12% 21% 10% 1	130500
	Night	54% 4 11% 19% 10% 1	127278
Seeing	Day	22% 16% 30% 20% 9% 3	15673
	Night	22% 12% 28% 27% 10% 1	24712

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	14% 17% 6% 16% 6% 5% 4 3 5% 5% 19%	3597
	11th to 20th	Day	13% 15% 7% 14% 6% 6% 5% 3 5% 5% 21%	3570
	21st to end	Day	11% 17% 7% 14% 6% 6% 5% 4 5% 6% 20%	4158
February	1st to 10th	Day	13% 16% 4 13% 7% 5% 4 4 5% 5% 24%	1800
	11th to 20th	Day	13% 15% 6% 10% 6% 5% 4 4 5% 6% 27%	1753
	21st to end	Day	20% 13% 4 9% 7% 4 4 4 5% 5% 25%	1646
March	1st to 10th	Day	20% 14% 5% 9% 6% 5% 4 3 4 5% 24%	4494
	11th to 20th	Day	13% 12% 4 9% 5% 5% 5% 5% 5% 7% 29%	4980
	21st to end	Day	18% 11% 3 7% 6% 4 3 3 4 5% 36%	5758
April	1st to 10th	Day	22% 12% 3 6% 4 4 4 3 4 7% 32%	2400
	11th to 20th	Day	22% 9% 3 6% 5% 3 3 3 4 5% 36%	2374
	21st to end	Day	21% 10% 3 8% 5% 4 3 4 5% 5% 32%	2547
May	1st to 10th	Day	23% 9% 3 8% 5% 5% 5% 4 6% 6% 27%	6346
	11th to 20th	Day	16% 9% 3 8% 5% 5% 5% 4 5% 7% 31%	6318
	21st to end	Day	21% 9% 3 7% 5% 4 4 3 5% 6% 33%	6949
June	1st to 10th	Day	20% 8% 3 8% 5% 5% 5% 4 5% 7% 30%	2800
	11th to 20th	Day	13% 6% 2 7% 5% 5% 4 5% 6% 8% 39%	2800
	21st to end	Day	19% 6% 3 6% 5% 5% 6% 5% 7% 8% 31%	2800
July	1st to 10th	Day	13% 6% 3 7% 5% 5% 5% 5% 7% 9% 34%	6360
	11th to 20th	Day	10% 5% 2 6% 4 5% 4 4 6% 8% 44%	6360
	21st to end	Day	9% 5% 2 5% 4 4 5% 4 7% 10% 46%	6926
August	1st to 10th	Day	13% 6% 3 8% 4 5% 5% 4 6% 8% 37%	4477
	11th to 20th	Day	16% 6% 2 6% 4 4 4 4 6% 9% 38%	4141
	21st to end	Day	13% 5% 2 6% 5% 5% 5% 4 6% 9% 40%	4312
September	1st to 10th	Day	13% 5% 2 6% 4 4 5% 4 5% 8% 43%	2400
	11th to 20th	Day	11% 5% 2 6% 4 4 4 4 5% 8% 48%	2400
	21st to end	Day	17% 5% 3 6% 5% 4 4 3 6% 8% 39%	2131
October	1st to 10th	Day	19% 7% 3 6% 4 4 5% 3 6% 6% 37%	2000
	11th to 20th	Day	22% 8% 2 8% 4 5% 5% 3 5% 7% 30%	1980
	21st to end	Day	25% 9% 3 8% 4 4 5% 4 4 5% 28%	1943
November	1st to 10th	Day	16% 9% 2 8% 4 5% 6% 4 6% 6% 33%	1756
	11th to 20th	Day	20% 12% 3 8% 5% 5% 5% 4 6% 6% 27%	1600
	21st to end	Day	22% 14% 4 11% 6% 6% 5% 4 4 5% 20%	1600
December	1st to 10th	Day	21% 20% 5% 10% 5% 5% 5% 4 5% 6% 14%	2600
	11th to 20th	Day	18% 16% 6% 11% 5% 4 4 3 4 4 24%	2986
	21st to end	Day	23% 16% 6% 11% 6% 4 4 3 3 4 20%	3960
January	1st to 10th	Night	14% 22% 8% 14% 5% 4 3 2 4 5% 19%	6349
	11th to 20th	Night	11% 15% 7% 14% 8% 6% 5% 3 4 5% 21%	6315
	21st to end	Night	12% 19% 6% 12% 7% 6% 5% 3 4 5% 20%	6794
February	1st to 10th	Night	13% 14% 4 13% 7% 5% 5% 3 5% 6% 24%	2600
	11th to 20th	Night	14% 13% 5% 11% 7% 5% 4 3 4 5% 28%	2533
	21st to end	Night	16% 13% 4 9% 6% 5% 5% 3 4 5% 29%	1982
March	1st to 10th	Night	22% 14% 4 10% 5% 4 3 2 3 4 28%	5329
	11th to 20th	Night	12% 12% 4 9% 6% 5% 4 4 6% 8% 29%	4979
	21st to end	Night	19% 10% 3 8% 5% 4 3 3 5% 6% 33%	5174
April	1st to 10th	Night	20% 10% 3 8% 4 5% 4 3 6% 5% 32%	2000
	11th to 20th	Night	19% 9% 3 8% 6% 3 4 3 4 5% 35%	1975
	21st to end	Night	21% 9% 3 7% 5% 4 4 3 5% 5% 35%	1870
May	1st to 10th	Night	22% 9% 3 8% 5% 5% 6% 5% 6% 7% 25%	3594
	11th to 20th	Night	16% 8% 3 6% 5% 4 5% 4 4 7% 37%	3575
	21st to end	Night	18% 9% 4 7% 5% 4 4 5% 6% 6% 31%	3926
June	1st to 10th	Night	15% 7% 3 7% 5% 5% 5% 4 6% 9% 35%	1600
	11th to 20th	Night	14% 5% 2 7% 5% 4 4 4 6% 7% 43%	1600
	21st to end	Night	18% 8% 2 6% 4 5% 5% 4 6% 7% 37%	1600
July	1st to 10th	Night	14% 7% 3 8% 5% 6% 5% 4 6% 8% 33%	3600
	11th to 20th	Night	12% 6% 3 7% 4 4 5% 4 5% 8% 42%	3600
	21st to end	Night	9% 6% 2 5% 5% 5% 5% 4 6% 8% 47%	3926
August	1st to 10th	Night	12% 7% 2 7% 4 5% 4 4 6% 9% 39%	2669
	11th to 20th	Night	15% 6% 3 6% 4 4 4 4 6% 7% 42%	2875
	21st to end	Night	13% 5% 2 6% 5% 4 5% 4 6% 8% 40%	3586
September	1st to 10th	Night	11% 5% 2 5% 5% 5% 4 3 5% 8% 47%	2000
	11th to 20th	Night	14% 4 2 6% 3 4 3 3 5% 6% 51%	2000
	21st to end	Night	18% 6% 2 6% 5% 4 3 2 5% 5% 44%	2264
October	1st to 10th	Night	17% 7% 2 6% 4 4 5% 4 4 6% 41%	2400
	11th to 20th	Night	20% 8% 2 7% 6% 6% 5% 3 5% 6% 32%	2377
	21st to end	Night	23% 10% 3 8% 5% 5% 5% 3 5% 6% 28%	2655
November	1st to 10th	Night	20% 10% 3 7% 5% 4 3 3 5% 6% 33%	2538
	11th to 20th	Night	19% 11% 4 8% 5% 5% 5% 4 5% 5% 29%	2800
	21st to end	Night	22% 13% 4 9% 6% 5% 4 3 5% 7% 23%	2800
December	1st to 10th	Night	20% 17% 5% 11% 7% 5% 5% 4 5% 6% 15%	4580
	11th to 20th	Night	23% 14% 4 10% 6% 4 3 2 3 4 26%	5208
	21st to end	Night	26% 18% 3 9% 4 3 4 3 4 4 21%	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	67% 3 11% 13% 5% 1	3598
	11th to 20th	Day	65% 3 11% 13% 7%	3600
	21st to end	Day	65% 4 10% 12% 8% 1	4158
February	1st to 10th	Day	62% 4 10% 17% 5% 2	1800
	11th to 20th	Day	58% 3 12% 16% 9% 1	1762
	21st to end	Day	60% 4 11% 14% 10% 1	1646
March	1st to 10th	Day	62% 3 9% 13% 12% 3	4497
	11th to 20th	Day	53% 4 17% 16% 9% 1	4980
	21st to end	Day	51% 3 6% 21% 17% 3	5758
April	1st to 10th	Day	53% 3 8% 20% 13% 3	2400
	11th to 20th	Day	51% 3 6% 22% 16% 2	2374
	21st to end	Day	55% 4 8% 16% 14% 4	2547
May	1st to 10th	Day	56% 4 8% 20% 9% 2	6357
	11th to 20th	Day	52% 5% 12% 18% 12% 1	6322
	21st to end	Day	51% 4 12% 20% 12% 1	6949
June	1st to 10th	Day	52% 5% 11% 20% 12% 1	2800
	11th to 20th	Day	41% 6% 13% 25% 13% 2	2800
	21st to end	Day	48% 6% 13% 22% 11% 1	2800
July	1st to 10th	Day	44% 5% 15% 26% 10%	6290
	11th to 20th	Day	36% 6% 13% 31% 14%	6285
	21st to end	Day	32% 6% 15% 36% 11%	6728
August	1st to 10th	Day	43% 6% 17% 24% 10%	4463
	11th to 20th	Day	42% 5% 15% 29% 9%	4180
	21st to end	Day	39% 5% 15% 28% 12% 1	4312
September	1st to 10th	Day	38% 6% 14% 29% 12%	2400
	11th to 20th	Day	35% 5% 14% 33% 13% 1	2400
	21st to end	Day	43% 6% 14% 26% 11%	2131
October	1st to 10th	Day	47% 5% 12% 29% 8%	3260
	11th to 20th	Day	46% 5% 15% 25% 9% 1	3220
	21st to end	Day	50% 5% 18% 20% 7%	3181
November	1st to 10th	Day	48% 5% 15% 24% 6% 1	1756
	11th to 20th	Day	57% 5% 13% 16% 8% 1	1600
	21st to end	Day	65% 6% 12% 9% 7% 1	1600
December	1st to 10th	Day	71% 5% 12% 10% 2	2600
	11th to 20th	Day	64% 4 10% 15% 7%	2986
	21st to end	Day	69% 3 8% 15% 4	3960
January	1st to 10th	Night	70% 2 11% 13% 4	6349
	11th to 20th	Night	65% 4 11% 14% 5%	6360
	21st to end	Night	67% 2 9% 10% 11% 1	6794
February	1st to 10th	Night	61% 4 10% 17% 7% 1	2600
	11th to 20th	Night	58% 4 10% 19% 8% 1	2535
	21st to end	Night	56% 4 10% 19% 10% 1	1982
March	1st to 10th	Night	62% 2 7% 15% 11% 3	5339
	11th to 20th	Night	52% 4 16% 17% 8% 3	4980
	21st to end	Night	52% 4 7% 22% 13% 3	5174
April	1st to 10th	Night	54% 4 9% 18% 14% 2	2000
	11th to 20th	Night	50% 4 7% 21% 16% 1	1975
	21st to end	Night	52% 4 7% 17% 16% 3	1870
May	1st to 10th	Night	57% 4 9% 19% 8% 3	3600
	11th to 20th	Night	45% 4 14% 20% 15% 1	3576
	21st to end	Night	51% 5% 13% 17% 14% 1	3927
June	1st to 10th	Night	45% 6% 13% 24% 10% 2	1600
	11th to 20th	Night	39% 5% 12% 26% 16% 2	1600
	21st to end	Night	45% 6% 12% 22% 14% 1	1600
July	1st to 10th	Night	47% 6% 16% 20% 12% 1	3560
	11th to 20th	Night	38% 6% 13% 32% 12%	3552
	21st to end	Night	35% 6% 12% 32% 16%	3809
August	1st to 10th	Night	41% 6% 15% 26% 11% 1	2659
	11th to 20th	Night	40% 5% 16% 29% 9%	2902
	21st to end	Night	40% 6% 15% 26% 12% 2	3586
September	1st to 10th	Night	35% 6% 12% 31% 15% 1	2000
	11th to 20th	Night	35% 4 14% 36% 11% 1	2000
	21st to end	Night	42% 4 12% 30% 12%	2264
October	1st to 10th	Night	39% 5% 13% 30% 12%	3920
	11th to 20th	Night	46% 5% 14% 25% 9%	3876
	21st to end	Night	50% 6% 17% 19% 8%	4367
November	1st to 10th	Night	52% 4 14% 21% 8%	2538
	11th to 20th	Night	56% 4 11% 19% 9% 1	2800
	21st to end	Night	61% 6% 13% 15% 5%	2800
December	1st to 10th	Night	68% 6% 12% 11% 2	4580
	11th to 20th	Night	64% 3 8% 14% 10% 1	5208
	21st to end	Night	69% 3 7% 12% 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	23% 23% 35% 15% 5%	200
	11th to 20th	Day	26% 18% 36% 17% 4 1	200
	21st to end	Day	20% 17% 39% 20% 4	261
February	1st to 10th	Day	29% 24% 32% 12% 3	300
	11th to 20th	Day	27% 30% 34% 7% 1	300
	21st to end	Day	30% 24% 29% 15% 2	410
March	1st to 10th	Day	29% 18% 32% 17% 4	500
	11th to 20th	Day	25% 21% 34% 16% 3 1	500
	21st to end	Day	31% 21% 28% 15% 6% 1	550
April	1st to 10th	Day	32% 21% 26% 14% 6% 1	500
	11th to 20th	Day	31% 20% 25% 13% 10% 2	492
	21st to end	Day	30% 21% 30% 12% 6% 1	500
May	1st to 10th	Day	25% 17% 31% 18% 6% 2	503
	11th to 20th	Day	17% 19% 31% 21% 9% 3	527
	21st to end	Day	20% 15% 30% 24% 10% 1	573
June	1st to 10th	Day	25% 12% 31% 23% 8% 2	530
	11th to 20th	Day	15% 16% 32% 24% 11% 3	530
	21st to end	Day	20% 14% 32% 21% 10% 3	530
July	1st to 10th	Day	12% 8% 28% 34% 15% 3	525
	11th to 20th	Day	13% 8% 33% 29% 14% 4	524
	21st to end	Day	13% 8% 32% 30% 13% 4	576
August	1st to 10th	Day	12% 7% 27% 33% 17% 4	526
	11th to 20th	Day	13% 8% 25% 29% 18% 7%	519
	21st to end	Day	15% 11% 28% 25% 14% 7%	583
September	1st to 10th	Day	16% 11% 29% 21% 15% 9%	530
	11th to 20th	Day	12% 8% 24% 23% 21% 12%	530
	21st to end	Day	18% 12% 31% 21% 14% 5%	530
October	1st to 10th	Day	22% 14% 25% 20% 14% 4	530
	11th to 20th	Day	24% 20% 29% 18% 7% 1	522
	21st to end	Day	30% 18% 26% 21% 6%	462
November	1st to 10th	Day	25% 18% 29% 18% 8% 1	390
	11th to 20th	Day	27% 22% 33% 13% 5% 1	200
	21st to end	Day	31% 19% 36% 11% 4 1	200
December	1st to 10th	Day	32% 16% 35% 14% 4	200
	11th to 20th	Day	31% 26% 32% 9% 3	200
	21st to end	Day	27% 21% 34% 14% 3 1	220
January	1st to 10th	Night	28% 15% 34% 20% 4	800
	11th to 20th	Night	27% 18% 27% 22% 6% 1	800
	21st to end	Night	19% 12% 37% 26% 5%	880
February	1st to 10th	Night	21% 17% 35% 23% 4	800
	11th to 20th	Night	22% 18% 38% 19% 4	783
	21st to end	Night	24% 18% 29% 25% 4	660
March	1st to 10th	Night	25% 15% 34% 23% 4	800
	11th to 20th	Night	23% 18% 31% 22% 5%	800
	21st to end	Night	25% 16% 28% 25% 6%	880
April	1st to 10th	Night	27% 14% 29% 25% 5%	800
	11th to 20th	Night	25% 17% 28% 22% 7%	791
	21st to end	Night	26% 13% 29% 24% 8%	670
May	1st to 10th	Night	24% 8% 27% 32% 9% 2	400
	11th to 20th	Night	22% 9% 29% 31% 10%	394
	21st to end	Night	17% 6% 35% 30% 12%	433
June	1st to 10th	Night	19% 4 32% 35% 11%	400
	11th to 20th	Night	16% 8% 26% 35% 13% 2	400
	21st to end	Night	23% 5% 27% 31% 14% 1	400
July	1st to 10th	Night	10% 4 28% 39% 18%	390
	11th to 20th	Night	12% 5% 24% 44% 15% 1	388
	21st to end	Night	9% 5% 23% 45% 16% 1	438
August	1st to 10th	Night	11% 3 20% 42% 23%	442
	11th to 20th	Night	12% 4 18% 38% 25% 3	594
	21st to end	Night	13% 6% 24% 36% 19% 2	880
September	1st to 10th	Night	13% 6% 29% 30% 21% 2	800
	11th to 20th	Night	16% 6% 20% 32% 23% 4	800
	21st to end	Night	21% 7% 23% 27% 20% 2	800
October	1st to 10th	Night	22% 10% 24% 28% 15% 1	800
	11th to 20th	Night	25% 13% 28% 25% 8% 1	793
	21st to end	Night	26% 15% 28% 25% 6%	836
November	1st to 10th	Night	26% 14% 26% 26% 8% 1	780
	11th to 20th	Night	23% 16% 33% 18% 9% 1	800
	21st to end	Night	30% 16% 27% 22% 6%	800
December	1st to 10th	Night	30% 15% 29% 22% 4	800
	11th to 20th	Night	29% 16% 29% 21% 5% 1	800
	21st to end	Night	33% 16% 28% 17% 5%	880

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