Prinyer's Cove
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Prinyer's Cove clear sky chart from 2005-11-06 to 2025-02-06.

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% 9% 3 8% 5% 5% 4 4 6% 7% 35%	108607
	Night	17% 10% 4 8% 5% 4 5% 4 5% 7% 32%	109632
Transparency	Day	27% 45% 8% 14% 6%	112185
	Night	31% 43% 6% 12% 7%	114218
Seeing	Day	19% 7% 24% 30% 16% 4	14737
	Night	21% 8% 27% 29% 13% 2	24085

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	12% 13% 5% 10% 5% 5% 5% 4 6% 7% 28%	3597
	11th to 20th	Day	12% 18% 7% 15% 9% 6% 5% 3 5% 4 17%	3570
	21st to end	Day	14% 16% 6% 12% 7% 6% 5% 4 5% 5% 19%	4397
February	1st to 10th	Day	15% 13% 5% 11% 7% 5% 5% 4 5% 6% 23%	1755
	11th to 20th	Day	14% 12% 6% 10% 6% 5% 6% 4 5% 5% 28%	1663
	21st to end	Day	20% 13% 4 8% 6% 5% 4 4 5% 5% 27%	1546
March	1st to 10th	Day	21% 10% 4 8% 6% 4 3 3 5% 4 32%	3239
	11th to 20th	Day	10% 12% 4 10% 6% 5% 5% 4 5% 6% 33%	3480
	21st to end	Day	14% 8% 3 6% 4 4 4 3 5% 6% 42%	3941
April	1st to 10th	Day	19% 10% 3 7% 5% 5% 4 4 4 6% 33%	2280
	11th to 20th	Day	19% 7% 3 7% 5% 4 3 4 4 7% 39%	2254
	21st to end	Day	20% 8% 3 7% 6% 4 4 4 6% 6% 32%	2389
May	1st to 10th	Day	18% 8% 3 8% 5% 4 4 4 6% 7% 33%	4358
	11th to 20th	Day	14% 9% 3 7% 5% 5% 4 4 6% 7% 36%	4398
	21st to end	Day	11% 5% 2 6% 4 5% 5% 4 6% 9% 43%	4837
June	1st to 10th	Day	16% 6% 2 7% 5% 4 5% 4 5% 9% 35%	2660
	11th to 20th	Day	13% 6% 2 5% 4 4 4 6% 7% 9% 41%	2660
	21st to end	Day	13% 7% 3 6% 5% 3 4 4 6% 8% 40%	2660
July	1st to 10th	Day	10% 5% 2 6% 4 4 4 4 7% 9% 44%	4440
	11th to 20th	Day	10% 4 2 5% 4 4 4 4 7% 10% 46%	4440
	21st to end	Day	8% 5% 2 6% 4 5% 5% 5% 7% 9% 43%	4814
August	1st to 10th	Day	16% 6% 2 6% 4 4 4 4 5% 7% 42%	4142
	11th to 20th	Day	14% 6% 2 6% 4 3 4 4 7% 10% 41%	4026
	21st to end	Day	13% 4 2 5% 4 4 4 4 6% 9% 44%	4180
September	1st to 10th	Day	10% 6% 2 5% 4 4 4 4 5% 8% 46%	2280
	11th to 20th	Day	10% 6% 2 5% 4 3 4 4 4 7% 52%	2280
	21st to end	Day	15% 6% 2 7% 4 5% 5% 3 6% 8% 39%	2005
October	1st to 10th	Day	18% 8% 3 6% 5% 4 4 3 6% 7% 37%	1900
	11th to 20th	Day	20% 7% 2 7% 5% 4 5% 3 7% 8% 33%	1900
	21st to end	Day	25% 10% 3 7% 4 6% 4 4 4 7% 26%	2017
November	1st to 10th	Day	15% 8% 3 6% 5% 5% 5% 4 6% 7% 35%	1753
	11th to 20th	Day	15% 10% 3 8% 6% 5% 6% 4 6% 7% 31%	1600
	21st to end	Day	20% 13% 3 8% 5% 5% 4 4 5% 7% 25%	1600
December	1st to 10th	Day	20% 14% 4 9% 6% 5% 5% 4 5% 7% 21%	2600
	11th to 20th	Day	18% 14% 5% 11% 6% 4 4 3 5% 6% 24%	2986
	21st to end	Day	25% 12% 4 9% 5% 5% 4 3 5% 7% 20%	3960
January	1st to 10th	Night	15% 14% 5% 11% 6% 5% 5% 4 5% 6% 25%	6349
	11th to 20th	Night	12% 14% 6% 17% 7% 7% 6% 4 5% 5% 16%	6315
	21st to end	Night	17% 15% 7% 12% 6% 6% 5% 4 5% 5% 19%	6555
February	1st to 10th	Night	17% 13% 5% 11% 6% 5% 5% 4 4 5% 25%	2536
	11th to 20th	Night	15% 13% 4 9% 4 5% 4 4 5% 6% 29%	2403
	21st to end	Night	17% 10% 4 9% 4 5% 5% 4 6% 7% 29%	1907
March	1st to 10th	Night	19% 10% 4 8% 5% 5% 4 3 5% 6% 33%	3598
	11th to 20th	Night	20% 13% 4 8% 4 4 4 3 5% 6% 29%	3479
	21st to end	Night	17% 8% 3 6% 3 3 3 3 5% 7% 43%	3690
April	1st to 10th	Night	21% 9% 3 6% 4 4 5% 3 5% 7% 34%	1900
	11th to 20th	Night	18% 8% 4 7% 4 4 4 3 5% 6% 36%	1875
	21st to end	Night	18% 9% 3 6% 5% 4 4 4 6% 6% 35%	1807
May	1st to 10th	Night	23% 9% 3 7% 4 4 4 3 5% 5% 33%	2580
	11th to 20th	Night	18% 7% 2 6% 4 4 5% 4 6% 7% 36%	2495
	21st to end	Night	11% 6% 2 6% 4 4 5% 5% 6% 7% 43%	2738
June	1st to 10th	Night	14% 6% 3 6% 5% 5% 5% 4 8% 9% 35%	1520
	11th to 20th	Night	10% 5% 2 6% 5% 4 4 5% 7% 8% 44%	1520
	21st to end	Night	13% 8% 3 7% 5% 3 5% 3 6% 8% 39%	1520
July	1st to 10th	Night	10% 5% 2 8% 5% 5% 5% 4 7% 8% 40%	2520
	11th to 20th	Night	12% 6% 2 5% 4 3 4 3 6% 9% 45%	2520
	21st to end	Night	9% 5% 2 5% 4 4 4 4 7% 8% 47%	2739
August	1st to 10th	Night	10% 6% 3 6% 4 4 5% 3 6% 8% 44%	2783
	11th to 20th	Night	13% 6% 3 6% 3 3 4 3 6% 8% 44%	2785
	21st to end	Night	8% 4 2 5% 5% 5% 5% 4 7% 10% 45%	3462
September	1st to 10th	Night	11% 6% 2 6% 4 3 4 3 6% 7% 48%	1900
	11th to 20th	Night	12% 3 2 4 4 3 3 4 5% 8% 52%	1900
	21st to end	Night	17% 6% 2 6% 4 3 4 4 5% 8% 42%	2171
October	1st to 10th	Night	16% 7% 3 8% 5% 5% 4 3 5% 7% 36%	2280
	11th to 20th	Night	20% 8% 3 7% 5% 5% 4 4 4 7% 34%	2280
	21st to end	Night	22% 9% 3 8% 4 4 5% 4 5% 6% 30%	2579
November	1st to 10th	Night	18% 8% 3 6% 4 4 4 4 5% 7% 38%	2542
	11th to 20th	Night	18% 9% 2 7% 5% 4 5% 4 5% 7% 34%	2800
	21st to end	Night	22% 10% 3 7% 5% 4 5% 4 6% 7% 26%	2800
December	1st to 10th	Night	21% 14% 3 8% 5% 5% 6% 4 6% 7% 21%	4580
	11th to 20th	Night	21% 14% 4 8% 4 3 3 3 5% 6% 28%	5208
	21st to end	Night	27% 13% 3 9% 5% 4 4 4 6% 5% 19%	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	40% 31% 7% 12% 8% 1	3598
	11th to 20th	Day	56% 29% 4 6% 4 1	3600
	21st to end	Day	49% 30% 7% 7% 7% 1	4397
February	1st to 10th	Day	24% 64% 4 6% 2 1	1755
	11th to 20th	Day	19% 64% 3 8% 5%	1672
	21st to end	Day	19% 66% 5% 5% 5% 1	1546
March	1st to 10th	Day	33% 43% 5% 13% 6% 1	3242
	11th to 20th	Day	28% 42% 11% 9% 8% 1	3480
	21st to end	Day	23% 41% 6% 18% 10% 2	3941
April	1st to 10th	Day	21% 65% 3 5% 5% 1	2280
	11th to 20th	Day	17% 66% 2 8% 6% 1	2254
	21st to end	Day	17% 66% 4 8% 5% 1	2389
May	1st to 10th	Day	31% 43% 6% 15% 5%	4372
	11th to 20th	Day	33% 43% 9% 12% 3	4402
	21st to end	Day	21% 42% 8% 19% 9% 1	4837
June	1st to 10th	Day	16% 66% 4 8% 6% 1	2660
	11th to 20th	Day	14% 66% 5% 8% 6% 1	2660
	21st to end	Day	14% 63% 4 11% 7% 1	2660
July	1st to 10th	Day	24% 36% 10% 19% 10% 1	4370
	11th to 20th	Day	21% 37% 10% 26% 6%	4365
	21st to end	Day	23% 38% 11% 21% 8%	4661
August	1st to 10th	Day	29% 38% 9% 14% 9% 1	4128
	11th to 20th	Day	27% 38% 11% 19% 5%	4065
	21st to end	Day	23% 38% 10% 22% 6%	4180
September	1st to 10th	Day	13% 61% 8% 13% 5%	2280
	11th to 20th	Day	10% 60% 5% 14% 10%	2280
	21st to end	Day	17% 60% 6% 12% 5%	2005
October	1st to 10th	Day	22% 39% 9% 23% 7%	3160
	11th to 20th	Day	23% 38% 12% 22% 5%	3140
	21st to end	Day	28% 38% 9% 19% 6%	3307
November	1st to 10th	Day	24% 58% 6% 7% 5%	1753
	11th to 20th	Day	21% 59% 5% 11% 4	1600
	21st to end	Day	26% 58% 6% 5% 4	1600
December	1st to 10th	Day	43% 37% 12% 5% 3	2600
	11th to 20th	Day	44% 34% 7% 9% 6%	2986
	21st to end	Day	46% 29% 9% 12% 4	3960
January	1st to 10th	Night	46% 31% 6% 12% 6%	6349
	11th to 20th	Night	54% 29% 6% 7% 4	6360
	21st to end	Night	52% 31% 4 6% 6%	6555
February	1st to 10th	Night	23% 64% 4 6% 2	2536
	11th to 20th	Night	19% 64% 5% 7% 5%	2405
	21st to end	Night	19% 65% 4 7% 5%	1907
March	1st to 10th	Night	31% 42% 4 15% 7%	3608
	11th to 20th	Night	36% 41% 8% 8% 6%	3480
	21st to end	Night	23% 41% 3 17% 14% 2	3690
April	1st to 10th	Night	19% 66% 3 7% 5%	1900
	11th to 20th	Night	16% 66% 3 6% 9% 1	1875
	21st to end	Night	17% 65% 4 6% 6% 1	1807
May	1st to 10th	Night	35% 42% 7% 10% 5% 1	2586
	11th to 20th	Night	32% 43% 9% 12% 3	2496
	21st to end	Night	22% 43% 7% 13% 14% 1	2739
June	1st to 10th	Night	15% 65% 3 9% 7% 1	1520
	11th to 20th	Night	15% 65% 3 8% 9% 1	1520
	21st to end	Night	17% 63% 3 8% 8% 1	1520
July	1st to 10th	Night	29% 36% 8% 15% 12% 1	2480
	11th to 20th	Night	24% 36% 8% 25% 8%	2472
	21st to end	Night	23% 37% 11% 20% 8% 1	2651
August	1st to 10th	Night	24% 38% 8% 19% 9% 1	2773
	11th to 20th	Night	26% 38% 10% 21% 5%	2812
	21st to end	Night	21% 39% 9% 24% 7%	3462
September	1st to 10th	Night	12% 61% 6% 15% 6% 1	1900
	11th to 20th	Night	12% 60% 4 14% 10% 1	1900
	21st to end	Night	16% 60% 5% 12% 7%	2171
October	1st to 10th	Night	21% 37% 7% 20% 14%	3800
	11th to 20th	Night	23% 38% 10% 22% 7%	3779
	21st to end	Night	28% 37% 9% 20% 6%	4239
November	1st to 10th	Night	23% 56% 6% 9% 5%	2542
	11th to 20th	Night	21% 58% 5% 10% 5% 1	2800
	21st to end	Night	25% 59% 5% 7% 4	2800
December	1st to 10th	Night	41% 37% 8% 11% 2	4580
	11th to 20th	Night	40% 34% 8% 8% 9% 1	5208
	21st to end	Night	49% 28% 7% 9% 7%	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% 13% 29% 26% 8% 2	200
	11th to 20th	Day	30% 13% 30% 20% 7% 1	200
	21st to end	Day	20% 14% 32% 25% 7% 2	315
February	1st to 10th	Day	26% 12% 38% 20% 5%	285
	11th to 20th	Day	20% 12% 35% 29% 4	270
	21st to end	Day	28% 14% 29% 25% 4	358
March	1st to 10th	Day	22% 7% 27% 37% 7% 1	460
	11th to 20th	Day	20% 12% 29% 30% 8%	460
	21st to end	Day	27% 8% 31% 22% 10% 2	506
April	1st to 10th	Day	23% 8% 28% 30% 10% 1	460
	11th to 20th	Day	24% 8% 28% 23% 13% 4	452
	21st to end	Day	25% 5% 25% 30% 13% 2	460
May	1st to 10th	Day	22% 5% 21% 33% 17% 3	463
	11th to 20th	Day	15% 3 21% 36% 20% 5%	487
	21st to end	Day	14% 2 20% 34% 20% 8%	529
June	1st to 10th	Day	16% 5% 19% 36% 21% 3	490
	11th to 20th	Day	13% 3 22% 34% 23% 5%	490
	21st to end	Day	18% 4 21% 34% 20% 4	490
July	1st to 10th	Day	12% 2 14% 35% 30% 6%	485
	11th to 20th	Day	12% 2 17% 33% 30% 6%	484
	21st to end	Day	11% 3 16% 40% 24% 5%	532
August	1st to 10th	Day	13% 2 12% 35% 31% 7%	486
	11th to 20th	Day	12% 3 14% 33% 27% 10%	479
	21st to end	Day	12% 4 18% 36% 21% 9%	539
September	1st to 10th	Day	13% 4 19% 31% 25% 8%	490
	11th to 20th	Day	11% 3 15% 29% 24% 18%	490
	21st to end	Day	15% 6% 20% 30% 22% 7%	490
October	1st to 10th	Day	21% 7% 29% 20% 16% 8%	490
	11th to 20th	Day	22% 10% 28% 24% 13% 3	490
	21st to end	Day	28% 11% 26% 25% 9% 1	500
November	1st to 10th	Day	21% 12% 28% 27% 11% 1	387
	11th to 20th	Day	18% 16% 32% 24% 9% 3	200
	21st to end	Day	24% 13% 37% 18% 8% 1	200
December	1st to 10th	Day	25% 17% 26% 25% 7% 2	200
	11th to 20th	Day	26% 19% 34% 17% 5% 1	200
	21st to end	Day	31% 13% 30% 21% 5%	220
January	1st to 10th	Night	27% 13% 34% 21% 5% 1	800
	11th to 20th	Night	28% 12% 31% 22% 7% 1	800
	21st to end	Night	23% 9% 32% 28% 8%	880
February	1st to 10th	Night	23% 11% 36% 26% 4	781
	11th to 20th	Night	20% 10% 36% 28% 6%	743
	21st to end	Night	22% 8% 37% 28% 5%	628
March	1st to 10th	Night	21% 7% 30% 36% 7%	760
	11th to 20th	Night	25% 8% 29% 30% 8% 1	760
	21st to end	Night	21% 6% 31% 31% 11% 1	836
April	1st to 10th	Night	24% 6% 28% 33% 8%	760
	11th to 20th	Night	22% 5% 33% 26% 12% 2	751
	21st to end	Night	23% 6% 23% 32% 15% 1	667
May	1st to 10th	Night	24% 3 19% 34% 16% 3	420
	11th to 20th	Night	14% 2 20% 44% 18% 2	374
	21st to end	Night	12% 1 24% 39% 20% 5%	411
June	1st to 10th	Night	17% 2 19% 39% 21% 2	380
	11th to 20th	Night	12% 3 19% 39% 24% 3	380
	21st to end	Night	16% 4 20% 37% 22% 1	380
July	1st to 10th	Night	8% 3 17% 39% 30% 2	370
	11th to 20th	Night	12% 3 15% 37% 29% 4	368
	21st to end	Night	11% 1 13% 48% 23% 3	416
August	1st to 10th	Night	11% 2 14% 39% 28% 5%	538
	11th to 20th	Night	14% 2 14% 33% 29% 7%	564
	21st to end	Night	10% 3 17% 39% 26% 4	822
September	1st to 10th	Night	14% 3 20% 35% 23% 6%	760
	11th to 20th	Night	14% 4 16% 27% 30% 10%	760
	21st to end	Night	20% 5% 21% 26% 23% 5%	760
October	1st to 10th	Night	21% 8% 25% 23% 18% 5%	760
	11th to 20th	Night	24% 10% 26% 27% 12% 1	760
	21st to end	Night	25% 11% 28% 26% 8%	836
November	1st to 10th	Night	24% 9% 26% 26% 13% 1	780
	11th to 20th	Night	23% 12% 33% 24% 8% 1	800
	21st to end	Night	29% 13% 30% 21% 7% 1	800
December	1st to 10th	Night	30% 14% 31% 19% 6%	800
	11th to 20th	Night	26% 14% 35% 20% 4 1	800
	21st to end	Night	33% 11% 33% 19% 4	880

Page generated at 2025-02-03 03:05:49. Version ac07

Copyright © 2025 Attilla Danko.