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 2024-01-27.

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% 8% 3 6% 6% 3 5% 5% 5% 7% 36%	74831
	Night	17% 9% 3 6% 6% 3 5% 5% 5% 7% 34%	75207
Transparency	Day	31% 38% 9% 14% 7% 1	74536
	Night	34% 38% 8% 13% 7% 1	75036
Seeing	Day	19% 6% 23% 30% 17% 4	13434
	Night	21% 7% 27% 29% 14% 2	22792

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	17% 14% 5% 7% 7% 2 6% 5% 5% 7% 25%	1517
	11th to 20th	Day	19% 17% 5% 7% 7% 4 5% 4 5% 4 23%	1520
	21st to end	Day	14% 13% 6% 9% 8% 5% 6% 6% 5% 6% 23%	1807
February	1st to 10th	Day	17% 12% 5% 11% 8% 4 5% 6% 5% 6% 21%	1620
	11th to 20th	Day	15% 11% 6% 10% 7% 3 6% 5% 5% 5% 27%	1573
	21st to end	Day	20% 12% 4 7% 6% 3 5% 5% 5% 5% 27%	1458
March	1st to 10th	Day	16% 8% 5% 8% 9% 5% 5% 4 5% 5% 30%	1864
	11th to 20th	Day	16% 10% 4 7% 6% 5% 4 5% 5% 5% 33%	1980
	21st to end	Day	20% 8% 3 7% 5% 3 4 4 4 6% 37%	2249
April	1st to 10th	Day	19% 9% 3 6% 6% 4 4 5% 4 6% 34%	2160
	11th to 20th	Day	18% 6% 3 6% 5% 3 3 4 3 7% 40%	2134
	21st to end	Day	20% 7% 3 6% 6% 3 5% 5% 6% 7% 32%	2263
May	1st to 10th	Day	15% 8% 3 7% 6% 4 4 5% 6% 7% 35%	2480
	11th to 20th	Day	14% 6% 2 4 4 3 4 5% 6% 8% 42%	2478
	21st to end	Day	12% 4 3 5% 5% 4 5% 5% 6% 9% 42%	2725
June	1st to 10th	Day	16% 5% 3 6% 6% 3 5% 5% 5% 9% 37%	2520
	11th to 20th	Day	13% 5% 2 5% 5% 3 4 6% 6% 9% 42%	2520
	21st to end	Day	13% 7% 3 6% 5% 2 4 5% 6% 8% 41%	2520
July	1st to 10th	Day	9% 5% 3 4 4 3 4 5% 6% 9% 48%	2520
	11th to 20th	Day	10% 4 2 4 5% 3 5% 6% 7% 9% 43%	2520
	21st to end	Day	9% 4 2 6% 5% 4 5% 6% 7% 10% 42%	2744
August	1st to 10th	Day	9% 4 2 5% 5% 3 5% 6% 6% 8% 45%	2351
	11th to 20th	Day	9% 5% 3 5% 5% 3 5% 6% 7% 10% 43%	2299
	21st to end	Day	12% 4 2 4 5% 3 5% 5% 6% 9% 45%	2376
September	1st to 10th	Day	11% 6% 2 5% 4 3 5% 5% 6% 8% 46%	2160
	11th to 20th	Day	11% 5% 3 4 4 2 4 4 5% 7% 51%	2160
	21st to end	Day	14% 5% 3 7% 5% 3 5% 4 6% 8% 40%	1900
October	1st to 10th	Day	18% 8% 3 5% 6% 3 3 4 6% 7% 37%	1800
	11th to 20th	Day	20% 7% 2 7% 6% 3 5% 5% 7% 8% 32%	1800
	21st to end	Day	26% 9% 3 6% 6% 4 5% 5% 4 7% 26%	1911
November	1st to 10th	Day	16% 7% 4 5% 6% 3 5% 6% 6% 8% 35%	1664
	11th to 20th	Day	16% 9% 3 8% 6% 4 6% 5% 5% 7% 31%	1520
	21st to end	Day	21% 12% 4 8% 6% 4 4 5% 5% 7% 25%	1520
December	1st to 10th	Day	22% 14% 4 8% 7% 4 5% 5% 5% 6% 21%	1520
	11th to 20th	Day	19% 14% 5% 8% 7% 3 4 4 4 6% 25%	1906
	21st to end	Day	29% 13% 5% 8% 6% 3 4 3 4 5% 20%	2772
January	1st to 10th	Night	20% 13% 5% 9% 8% 4 4 4 5% 6% 23%	2649
	11th to 20th	Night	20% 13% 5% 9% 7% 5% 5% 5% 4 6% 20%	2660
	21st to end	Night	15% 14% 4 9% 7% 4 5% 4 5% 6% 27%	2689
February	1st to 10th	Night	18% 12% 5% 11% 7% 4 5% 4 4 5% 24%	2340
	11th to 20th	Night	16% 12% 5% 8% 5% 3 5% 5% 5% 6% 29%	2273
	21st to end	Night	18% 9% 4 7% 6% 4 5% 5% 5% 7% 29%	1798
March	1st to 10th	Night	15% 10% 4 8% 7% 4 5% 4 5% 6% 33%	2080
	11th to 20th	Night	19% 10% 5% 5% 5% 3 4 4 4 5% 35%	1979
	21st to end	Night	17% 8% 3 7% 5% 3 3 4 5% 6% 39%	2106
April	1st to 10th	Night	21% 8% 3 6% 4 3 5% 4 5% 7% 35%	1800
	11th to 20th	Night	18% 7% 4 6% 5% 3 4 5% 5% 6% 37%	1775
	21st to end	Night	19% 9% 3 6% 5% 3 4 5% 6% 7% 34%	1712
May	1st to 10th	Night	21% 6% 3 4 5% 3 4 5% 5% 6% 38%	1478
	11th to 20th	Night	13% 4 3 5% 5% 3 5% 5% 6% 7% 44%	1415
	21st to end	Night	10% 5% 2 5% 5% 3 5% 5% 6% 7% 46%	1550
June	1st to 10th	Night	15% 6% 3 6% 5% 4 5% 5% 7% 9% 35%	1440
	11th to 20th	Night	11% 4 2 5% 5% 3 5% 5% 7% 8% 45%	1440
	21st to end	Night	13% 7% 3 6% 5% 3 5% 4 6% 9% 40%	1440
July	1st to 10th	Night	8% 3 2 5% 5% 4 5% 4 6% 8% 50%	1440
	11th to 20th	Night	11% 5% 2 5% 5% 3 4 5% 7% 9% 44%	1440
	21st to end	Night	10% 5% 2 4 5% 2 4 5% 7% 9% 47%	1574
August	1st to 10th	Night	8% 5% 2 5% 6% 3 5% 4 6% 8% 47%	1583
	11th to 20th	Night	10% 6% 3 5% 5% 3 5% 5% 6% 9% 44%	1598
	21st to end	Night	9% 5% 2 4 5% 3 5% 5% 6% 9% 46%	1966
September	1st to 10th	Night	11% 5% 3 5% 5% 3 4 3 6% 7% 47%	1800
	11th to 20th	Night	13% 3 2 4 4 2 3 4 5% 8% 51%	1800
	21st to end	Night	16% 6% 2 5% 4 2 5% 4 5% 8% 43%	2056
October	1st to 10th	Night	16% 7% 3 7% 7% 4 4 4 5% 7% 36%	2160
	11th to 20th	Night	20% 7% 4 7% 6% 3 5% 5% 4 7% 33%	2160
	21st to end	Night	23% 8% 4 7% 6% 3 5% 5% 4 6% 29%	2443
November	1st to 10th	Night	18% 7% 3 5% 4 3 4 4 5% 8% 38%	2411
	11th to 20th	Night	18% 8% 3 6% 5% 3 5% 5% 5% 7% 33%	2660
	21st to end	Night	23% 9% 4 6% 6% 3 5% 6% 6% 7% 26%	2660
December	1st to 10th	Night	22% 13% 4 7% 6% 3 5% 4 5% 7% 23%	2660
	11th to 20th	Night	20% 13% 4 7% 5% 3 4 4 5% 5% 29%	3288
	21st to end	Night	31% 13% 4 7% 6% 3 4 5% 5% 5% 18%	4884

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% 41% 6% 11% 2	1518
	11th to 20th	Day	43% 41% 7% 6% 4 1	1520
	21st to end	Day	42% 37% 8% 8% 5%	1807
February	1st to 10th	Day	40% 38% 9% 10% 2	1620
	11th to 20th	Day	40% 38% 6% 9% 5% 1	1582
	21st to end	Day	40% 36% 8% 10% 6%	1458
March	1st to 10th	Day	35% 37% 10% 12% 6%	1867
	11th to 20th	Day	35% 37% 8% 14% 6% 1	1980
	21st to end	Day	30% 37% 7% 14% 10% 2	2249
April	1st to 10th	Day	31% 36% 7% 15% 8% 2	2160
	11th to 20th	Day	30% 36% 6% 15% 11% 2	2134
	21st to end	Day	34% 37% 6% 12% 9% 3	2263
May	1st to 10th	Day	29% 37% 7% 12% 11% 3	2480
	11th to 20th	Day	25% 38% 7% 17% 10% 2	2482
	21st to end	Day	24% 38% 11% 16% 9% 3	2725
June	1st to 10th	Day	30% 38% 10% 13% 8% 1	2520
	11th to 20th	Day	25% 36% 9% 19% 9% 1	2520
	21st to end	Day	27% 38% 12% 14% 8% 1	2520
July	1st to 10th	Day	22% 39% 9% 20% 9%	2450
	11th to 20th	Day	21% 39% 12% 20% 7%	2445
	21st to end	Day	23% 41% 11% 18% 7%	2591
August	1st to 10th	Day	24% 38% 11% 20% 7%	2337
	11th to 20th	Day	20% 37% 14% 18% 10% 1	2299
	21st to end	Day	22% 39% 9% 21% 8% 1	2376
September	1st to 10th	Day	26% 36% 10% 20% 8%	2160
	11th to 20th	Day	24% 38% 9% 19% 9% 1	2160
	21st to end	Day	30% 38% 9% 19% 5%	1900
October	1st to 10th	Day	31% 38% 9% 14% 8%	1800
	11th to 20th	Day	34% 38% 12% 12% 4	1800
	21st to end	Day	41% 37% 7% 10% 5%	1911
November	1st to 10th	Day	26% 43% 10% 14% 7%	1664
	11th to 20th	Day	33% 42% 8% 10% 6% 1	1520
	21st to end	Day	38% 42% 8% 9% 3	1520
December	1st to 10th	Day	41% 42% 9% 6% 1	1520
	11th to 20th	Day	44% 35% 11% 8% 2	1906
	21st to end	Day	54% 28% 6% 11% 1	2772
January	1st to 10th	Night	42% 42% 6% 8% 3	2649
	11th to 20th	Night	45% 41% 6% 5% 3	2660
	21st to end	Night	40% 36% 8% 9% 5% 1	2689
February	1st to 10th	Night	42% 37% 9% 10% 2	2340
	11th to 20th	Night	39% 37% 7% 12% 4	2275
	21st to end	Night	36% 37% 9% 13% 4 1	1798
March	1st to 10th	Night	35% 37% 8% 13% 6% 1	2090
	11th to 20th	Night	35% 37% 8% 13% 7% 1	1980
	21st to end	Night	30% 36% 7% 13% 11% 2	2106
April	1st to 10th	Night	32% 36% 6% 15% 9% 2	1800
	11th to 20th	Night	34% 36% 6% 13% 10% 1	1775
	21st to end	Night	32% 37% 7% 11% 10% 3	1712
May	1st to 10th	Night	31% 36% 6% 12% 13% 2	1478
	11th to 20th	Night	25% 36% 8% 16% 12% 3	1416
	21st to end	Night	23% 39% 8% 15% 12% 3	1551
June	1st to 10th	Night	30% 39% 9% 15% 7% 1	1440
	11th to 20th	Night	23% 38% 10% 15% 13% 1	1440
	21st to end	Night	28% 38% 10% 15% 8%	1440
July	1st to 10th	Night	22% 40% 7% 16% 14% 1	1400
	11th to 20th	Night	24% 39% 8% 19% 9%	1392
	21st to end	Night	22% 39% 8% 20% 9% 1	1486
August	1st to 10th	Night	25% 38% 10% 19% 8%	1573
	11th to 20th	Night	24% 36% 10% 17% 12% 1	1598
	21st to end	Night	22% 40% 10% 18% 9% 1	1966
September	1st to 10th	Night	26% 38% 10% 17% 9% 1	1800
	11th to 20th	Night	23% 37% 10% 21% 9%	1800
	21st to end	Night	28% 38% 8% 18% 7% 1	2056
October	1st to 10th	Night	33% 37% 8% 14% 7% 1	2160
	11th to 20th	Night	37% 37% 10% 12% 4	2160
	21st to end	Night	39% 39% 8% 7% 7%	2443
November	1st to 10th	Night	27% 42% 8% 15% 7% 1	2411
	11th to 20th	Night	31% 41% 9% 12% 6% 1	2660
	21st to end	Night	37% 42% 10% 9% 2	2660
December	1st to 10th	Night	43% 42% 7% 7% 1	2660
	11th to 20th	Night	42% 35% 10% 9% 4	3288
	21st to end	Night	55% 27% 9% 8% 1	4884

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	24% 13% 24% 28% 8% 2	180
	11th to 20th	Day	30% 13% 29% 20% 8% 1	180
	21st to end	Day	22% 11% 33% 24% 7% 2	268
February	1st to 10th	Day	29% 11% 39% 18% 3	240
	11th to 20th	Day	21% 13% 35% 27% 4	240
	21st to end	Day	30% 13% 29% 24% 3	324
March	1st to 10th	Day	21% 7% 28% 37% 7%	420
	11th to 20th	Day	22% 11% 29% 29% 9%	420
	21st to end	Day	29% 7% 29% 22% 11% 2	462
April	1st to 10th	Day	22% 9% 29% 28% 10% 1	420
	11th to 20th	Day	23% 7% 28% 24% 14% 5%	412
	21st to end	Day	26% 5% 25% 30% 13% 1	420
May	1st to 10th	Day	22% 4 21% 32% 17% 3	423
	11th to 20th	Day	16% 2 22% 37% 19% 4	447
	21st to end	Day	15% 2 20% 34% 20% 9%	485
June	1st to 10th	Day	16% 4 20% 37% 20% 2	450
	11th to 20th	Day	14% 3 20% 34% 24% 5%	450
	21st to end	Day	17% 3 19% 36% 22% 4	450
July	1st to 10th	Day	11% 1 13% 36% 32% 7%	445
	11th to 20th	Day	12% 1 15% 34% 31% 7%	444
	21st to end	Day	11% 3 15% 40% 25% 5%	488
August	1st to 10th	Day	12% 2 11% 36% 32% 7%	446
	11th to 20th	Day	12% 2 13% 34% 28% 10%	439
	21st to end	Day	12% 4 17% 36% 22% 10%	495
September	1st to 10th	Day	12% 3 19% 32% 25% 9%	450
	11th to 20th	Day	12% 3 16% 29% 24% 16%	450
	21st to end	Day	14% 5% 21% 31% 22% 7%	450
October	1st to 10th	Day	22% 6% 28% 19% 17% 8%	450
	11th to 20th	Day	22% 10% 27% 25% 14% 2	450
	21st to end	Day	30% 10% 24% 26% 9%	460
November	1st to 10th	Day	21% 11% 27% 28% 12% 1	358
	11th to 20th	Day	19% 15% 31% 24% 8% 3	180
	21st to end	Day	22% 13% 37% 18% 8% 1	180
December	1st to 10th	Day	24% 17% 26% 26% 6% 2	180
	11th to 20th	Day	22% 19% 34% 18% 6% 1	180
	21st to end	Day	32% 13% 32% 20% 3	198
January	1st to 10th	Night	28% 12% 33% 21% 6% 1	760
	11th to 20th	Night	28% 12% 30% 23% 7% 1	760
	21st to end	Night	23% 8% 33% 28% 8%	820
February	1st to 10th	Night	23% 11% 37% 25% 4	720
	11th to 20th	Night	21% 9% 36% 27% 6%	703
	21st to end	Night	23% 7% 38% 28% 5%	592
March	1st to 10th	Night	21% 7% 30% 36% 6%	720
	11th to 20th	Night	25% 8% 29% 30% 7% 1	720
	21st to end	Night	21% 6% 30% 31% 11% 1	792
April	1st to 10th	Night	24% 7% 29% 32% 8%	720
	11th to 20th	Night	22% 5% 33% 26% 12% 2	711
	21st to end	Night	23% 6% 23% 32% 15% 1	632
May	1st to 10th	Night	24% 3 20% 34% 17% 3	398
	11th to 20th	Night	14% 2 20% 46% 16% 2	354
	21st to end	Night	12% 1 24% 40% 19% 5%	389
June	1st to 10th	Night	17% 2 19% 39% 20% 2	360
	11th to 20th	Night	13% 3 19% 39% 23% 3	360
	21st to end	Night	16% 4 19% 38% 23% 1	360
July	1st to 10th	Night	8% 2 17% 39% 31% 2	350
	11th to 20th	Night	12% 3 14% 37% 29% 4	348
	21st to end	Night	11% 2 14% 48% 23% 3	394
August	1st to 10th	Night	11% 2 13% 40% 29% 5%	509
	11th to 20th	Night	13% 3 13% 34% 30% 7%	534
	21st to end	Night	10% 3 17% 39% 26% 4	778
September	1st to 10th	Night	14% 3 19% 35% 23% 6%	720
	11th to 20th	Night	14% 4 16% 28% 29% 9%	720
	21st to end	Night	19% 5% 21% 27% 23% 5%	720
October	1st to 10th	Night	22% 8% 25% 22% 18% 5%	720
	11th to 20th	Night	24% 10% 26% 27% 12% 1	720
	21st to end	Night	26% 11% 28% 27% 8%	792
November	1st to 10th	Night	24% 8% 26% 27% 13% 1	740
	11th to 20th	Night	23% 12% 32% 24% 9% 1	760
	21st to end	Night	28% 12% 30% 22% 8% 1	760
December	1st to 10th	Night	30% 14% 31% 19% 6%	760
	11th to 20th	Night	26% 14% 35% 21% 4 1	760
	21st to end	Night	33% 11% 33% 19% 4	836

Page generated at 2024-01-24 09:37:28. Version ac07

Copyright 2024 Attilla Danko