Pulpit Rock Astronomical Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Pulpit Rock Astronomical Park clear sky chart from 2005-11-06 to 2024-04-10.

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	17% 7% 3 5% 5% 3 5% 5% 5% 7% 38%	83132
	Night	17% 7% 3 5% 5% 3 4 4 5% 7% 41%	85638
Transparency	Day	43% 6% 12% 22% 14% 2	82841
	Night	42% 6% 12% 23% 15% 2	85463
Seeing	Day	21% 14% 28% 22% 11% 4	14075
	Night	20% 11% 27% 30% 11% 1	23537

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	15% 7% 3 6% 5% 3 4 5% 5% 5% 41%	2517
	11th to 20th	Day	14% 11% 6% 11% 6% 4 5% 4 5% 7% 27%	2623
	21st to end	Day	21% 12% 4 6% 6% 3 4 4 3 5% 31%	3124
February	1st to 10th	Day	16% 7% 3 6% 6% 4 5% 6% 5% 6% 35%	1710
	11th to 20th	Day	15% 8% 3 6% 6% 4 4 5% 5% 8% 37%	1755
	21st to end	Day	21% 9% 3 6% 5% 4 4 4 4 5% 34%	1570
March	1st to 10th	Day	26% 6% 3 5% 4 3 4 4 5% 6% 34%	3198
	11th to 20th	Day	10% 6% 2 6% 7% 3 5% 5% 5% 7% 43%	3480
	21st to end	Day	21% 8% 2 4 4 2 3 4 4 5% 43%	3994
April	1st to 10th	Day	17% 7% 4 6% 6% 3 5% 5% 5% 6% 37%	2270
	11th to 20th	Day	17% 6% 3 6% 5% 3 4 5% 5% 6% 40%	2134
	21st to end	Day	18% 5% 3 4 5% 3 5% 5% 6% 7% 39%	2160
May	1st to 10th	Day	20% 6% 2 6% 6% 3 5% 5% 6% 7% 35%	2350
	11th to 20th	Day	20% 7% 3 6% 6% 3 5% 5% 5% 7% 33%	2478
	21st to end	Day	16% 6% 3 4 5% 3 5% 5% 6% 8% 39%	2725
June	1st to 10th	Day	14% 6% 3 5% 5% 4 6% 5% 7% 9% 37%	2520
	11th to 20th	Day	16% 6% 2 5% 6% 4 5% 6% 6% 10% 35%	2520
	21st to end	Day	12% 5% 2 5% 5% 4 6% 5% 7% 10% 40%	2520
July	1st to 10th	Day	11% 6% 2 6% 7% 3 6% 6% 7% 11% 36%	2520
	11th to 20th	Day	9% 5% 2 5% 5% 4 5% 6% 6% 10% 43%	2520
	21st to end	Day	11% 6% 3 7% 6% 4 6% 6% 6% 8% 38%	2673
August	1st to 10th	Day	12% 5% 3 6% 6% 4 6% 6% 8% 9% 35%	2327
	11th to 20th	Day	12% 6% 2 6% 6% 3 5% 6% 6% 9% 39%	2178
	21st to end	Day	15% 5% 2 5% 5% 3 5% 5% 7% 9% 38%	2376
September	1st to 10th	Day	18% 5% 2 5% 4 3 4 4 6% 6% 43%	2160
	11th to 20th	Day	13% 4 2 4 4 2 4 4 5% 8% 50%	2160
	21st to end	Day	20% 7% 2 5% 4 3 4 4 5% 5% 41%	1931
October	1st to 10th	Day	20% 5% 2 5% 4 3 3 5% 5% 8% 41%	1800
	11th to 20th	Day	18% 5% 2 4 5% 3 4 4 6% 6% 43%	1800
	21st to end	Day	22% 7% 2 4 5% 2 4 5% 5% 6% 39%	1944
November	1st to 10th	Day	15% 7% 2 4 4 2 3 3 3 7% 51%	1671
	11th to 20th	Day	18% 6% 2 4 4 3 4 4 5% 7% 43%	1706
	21st to end	Day	18% 4 3 4 5% 3 5% 4 4 8% 41%	1520
December	1st to 10th	Day	21% 9% 2 7% 6% 3 4 4 5% 6% 34%	1520
	11th to 20th	Day	22% 7% 2 5% 5% 3 4 5% 4 6% 37%	1906
	21st to end	Day	20% 8% 4 8% 6% 3 5% 5% 5% 7% 29%	2772
January	1st to 10th	Night	16% 7% 3 6% 5% 3 4 4 5% 8% 40%	4429
	11th to 20th	Night	17% 7% 3 6% 6% 4 5% 5% 5% 6% 35%	4335
	21st to end	Night	24% 8% 3 6% 5% 2 4 4 4 5% 35%	4532
February	1st to 10th	Night	17% 7% 3 6% 5% 2 5% 4 4 7% 39%	2470
	11th to 20th	Night	17% 6% 3 6% 6% 3 5% 5% 5% 6% 39%	2309
	21st to end	Night	19% 8% 2 5% 5% 3 3 4 5% 7% 39%	1884
March	1st to 10th	Night	22% 11% 3 5% 5% 2 3 3 4 5% 37%	3638
	11th to 20th	Night	12% 7% 2 5% 6% 3 4 4 5% 6% 47%	3479
	21st to end	Night	17% 9% 3 5% 4 3 3 3 4 5% 45%	3636
April	1st to 10th	Night	18% 6% 3 6% 5% 3 5% 5% 5% 6% 38%	1900
	11th to 20th	Night	14% 6% 3 5% 5% 3 5% 4 6% 8% 41%	1775
	21st to end	Night	21% 4 2 4 3 3 4 5% 5% 6% 43%	1800
May	1st to 10th	Night	21% 8% 3 5% 5% 3 4 4 4 6% 37%	1625
	11th to 20th	Night	18% 6% 2 5% 6% 4 5% 4 5% 6% 39%	1415
	21st to end	Night	16% 5% 2 5% 5% 4 5% 4 5% 8% 40%	1550
June	1st to 10th	Night	17% 6% 3 5% 4 3 4 4 5% 8% 42%	1440
	11th to 20th	Night	14% 5% 2 5% 5% 3 5% 5% 6% 9% 41%	1440
	21st to end	Night	12% 4 2 4 4 3 5% 5% 6% 10% 44%	1440
July	1st to 10th	Night	11% 5% 2 6% 6% 4 6% 5% 7% 9% 39%	1440
	11th to 20th	Night	10% 4 3 5% 5% 3 4 5% 6% 10% 45%	1440
	21st to end	Night	10% 6% 2 4 6% 3 6% 6% 7% 9% 40%	1641
August	1st to 10th	Night	12% 5% 2 4 4 4 5% 5% 7% 8% 43%	1611
	11th to 20th	Night	13% 6% 3 7% 6% 4 5% 5% 6% 8% 38%	1703
	21st to end	Night	13% 5% 3 5% 5% 3 5% 6% 5% 9% 41%	1980
September	1st to 10th	Night	16% 5% 3 5% 5% 2 3 4 4 7% 46%	1800
	11th to 20th	Night	13% 5% 2 4 4 3 4 3 4 6% 51%	1800
	21st to end	Night	18% 4 2 5% 4 3 5% 4 4 5% 45%	2025
October	1st to 10th	Night	23% 5% 2 4 4 3 3 4 4 8% 42%	2160
	11th to 20th	Night	18% 6% 2 4 4 3 4 4 5% 7% 46%	2160
	21st to end	Night	21% 5% 2 3 4 3 4 4 4 6% 44%	2412
November	1st to 10th	Night	13% 5% 2 4 4 2 4 4 5% 6% 51%	2407
	11th to 20th	Night	16% 7% 3 5% 4 2 4 3 5% 5% 45%	2470
	21st to end	Night	15% 5% 3 5% 4 3 5% 4 5% 8% 42%	2660
December	1st to 10th	Night	21% 6% 3 5% 5% 3 6% 5% 5% 6% 35%	2660
	11th to 20th	Night	19% 8% 3 5% 5% 3 5% 4 5% 7% 38%	3288
	21st to end	Night	19% 8% 3 6% 6% 3 4 4 5% 7% 34%	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	42% 5% 15% 26% 10% 2	2518
	11th to 20th	Day	53% 6% 13% 16% 11% 2	2623
	21st to end	Day	54% 6% 13% 19% 8% 1	3124
February	1st to 10th	Day	46% 6% 14% 20% 12% 1	1710
	11th to 20th	Day	45% 5% 11% 24% 13% 2	1764
	21st to end	Day	51% 5% 11% 20% 11% 3	1570
March	1st to 10th	Day	49% 5% 10% 26% 8% 2	3201
	11th to 20th	Day	36% 7% 13% 28% 13% 3	3480
	21st to end	Day	45% 4 10% 19% 19% 3	3994
April	1st to 10th	Day	45% 5% 10% 21% 14% 5%	2270
	11th to 20th	Day	42% 6% 10% 22% 15% 4	2134
	21st to end	Day	42% 6% 11% 21% 15% 5%	2160
May	1st to 10th	Day	47% 6% 10% 20% 14% 3	2350
	11th to 20th	Day	49% 6% 10% 20% 13% 2	2482
	21st to end	Day	42% 7% 14% 22% 13% 2	2725
June	1st to 10th	Day	41% 8% 14% 23% 13% 2	2520
	11th to 20th	Day	43% 9% 14% 22% 10% 2	2520
	21st to end	Day	38% 8% 15% 25% 14% 1	2520
July	1st to 10th	Day	41% 8% 14% 21% 15% 1	2450
	11th to 20th	Day	35% 8% 14% 26% 15% 2	2445
	21st to end	Day	42% 8% 11% 22% 15% 3	2523
August	1st to 10th	Day	41% 8% 14% 21% 15% 1	2314
	11th to 20th	Day	40% 8% 15% 22% 14% 1	2178
	21st to end	Day	39% 6% 13% 22% 17% 3	2376
September	1st to 10th	Day	42% 6% 10% 21% 18% 3	2160
	11th to 20th	Day	34% 4 11% 24% 23% 4	2160
	21st to end	Day	45% 5% 8% 19% 21% 2	1931
October	1st to 10th	Day	42% 5% 13% 23% 15% 2	1800
	11th to 20th	Day	41% 4 12% 24% 17% 1	1800
	21st to end	Day	43% 6% 10% 23% 15% 2	1944
November	1st to 10th	Day	35% 4 14% 25% 19% 3	1671
	11th to 20th	Day	39% 6% 11% 24% 18% 2	1706
	21st to end	Day	41% 5% 13% 30% 9% 2	1520
December	1st to 10th	Day	51% 5% 15% 18% 10% 1	1520
	11th to 20th	Day	47% 5% 15% 25% 8% 1	1906
	21st to end	Day	52% 7% 14% 20% 7%	2772
January	1st to 10th	Night	41% 6% 13% 26% 11% 2	4429
	11th to 20th	Night	46% 6% 13% 23% 10% 2	4335
	21st to end	Night	51% 4 10% 23% 9% 1	4532
February	1st to 10th	Night	44% 5% 13% 26% 10% 2	2470
	11th to 20th	Night	45% 5% 11% 20% 17% 3	2311
	21st to end	Night	45% 5% 9% 22% 16% 4	1884
March	1st to 10th	Night	50% 4 9% 24% 11% 2	3648
	11th to 20th	Night	35% 6% 13% 29% 16% 2	3480
	21st to end	Night	43% 4 8% 18% 22% 5%	3636
April	1st to 10th	Night	45% 5% 10% 22% 14% 3	1900
	11th to 20th	Night	40% 7% 11% 20% 20% 2	1775
	21st to end	Night	41% 6% 12% 20% 17% 5%	1800
May	1st to 10th	Night	47% 6% 10% 19% 15% 3	1625
	11th to 20th	Night	45% 7% 11% 17% 17% 3	1416
	21st to end	Night	42% 8% 15% 18% 14% 3	1551
June	1st to 10th	Night	40% 7% 11% 22% 18% 1	1440
	11th to 20th	Night	38% 9% 14% 24% 14% 1	1440
	21st to end	Night	35% 8% 14% 29% 13% 1	1440
July	1st to 10th	Night	40% 10% 13% 20% 15% 2	1400
	11th to 20th	Night	34% 7% 17% 26% 14% 2	1392
	21st to end	Night	35% 11% 16% 22% 15% 2	1550
August	1st to 10th	Night	36% 9% 16% 22% 17% 1	1600
	11th to 20th	Night	43% 8% 14% 18% 15% 2	1703
	21st to end	Night	38% 8% 13% 20% 19% 2	1980
September	1st to 10th	Night	39% 6% 10% 23% 19% 3	1800
	11th to 20th	Night	35% 5% 9% 24% 25% 3	1800
	21st to end	Night	41% 5% 8% 21% 22% 2	2025
October	1st to 10th	Night	41% 6% 11% 24% 15% 2	2160
	11th to 20th	Night	38% 5% 12% 28% 15% 2	2160
	21st to end	Night	40% 5% 10% 27% 16% 2	2412
November	1st to 10th	Night	34% 5% 14% 25% 18% 4	2407
	11th to 20th	Night	41% 4 9% 25% 17% 4	2470
	21st to end	Night	39% 5% 13% 29% 13% 2	2660
December	1st to 10th	Night	48% 6% 13% 20% 12% 1	2660
	11th to 20th	Night	45% 6% 12% 22% 13% 2	3288
	21st to end	Night	48% 6% 14% 22% 9%	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% 27% 27% 17% 4 1	180
	11th to 20th	Day	31% 26% 30% 10% 2	211
	21st to end	Day	24% 25% 32% 14% 4 1	297
February	1st to 10th	Day	24% 26% 31% 14% 4	270
	11th to 20th	Day	26% 22% 37% 14% 1	362
	21st to end	Day	30% 16% 29% 23% 2	382
March	1st to 10th	Day	25% 21% 30% 20% 3	460
	11th to 20th	Day	22% 27% 30% 15% 4 1	460
	21st to end	Day	28% 21% 29% 16% 5% 2	506
April	1st to 10th	Day	25% 21% 31% 17% 5% 2	457
	11th to 20th	Day	21% 23% 28% 17% 10% 2	412
	21st to end	Day	28% 15% 32% 16% 5% 3	420
May	1st to 10th	Day	30% 16% 24% 19% 9% 3	423
	11th to 20th	Day	23% 14% 33% 20% 9% 2	447
	21st to end	Day	21% 6% 25% 25% 16% 6%	485
June	1st to 10th	Day	15% 13% 32% 23% 13% 4	450
	11th to 20th	Day	21% 11% 29% 22% 14% 3	450
	21st to end	Day	16% 10% 31% 25% 13% 5%	450
July	1st to 10th	Day	15% 4 23% 29% 20% 9%	445
	11th to 20th	Day	9% 5% 25% 32% 24% 5%	444
	21st to end	Day	14% 6% 28% 32% 16% 5%	488
August	1st to 10th	Day	11% 4 23% 30% 22% 10%	446
	11th to 20th	Day	15% 4 20% 34% 20% 8%	439
	21st to end	Day	15% 4 25% 29% 16% 11%	495
September	1st to 10th	Day	20% 9% 20% 22% 21% 8%	450
	11th to 20th	Day	14% 4 23% 29% 19% 11%	450
	21st to end	Day	25% 10% 22% 21% 17% 4	450
October	1st to 10th	Day	26% 7% 22% 23% 16% 7%	450
	11th to 20th	Day	20% 12% 28% 24% 14% 2	450
	21st to end	Day	24% 14% 30% 20% 11% 1	477
November	1st to 10th	Day	19% 13% 24% 27% 13% 3	365
	11th to 20th	Day	21% 17% 30% 25% 7%	366
	21st to end	Day	22% 22% 33% 18% 4 1	180
December	1st to 10th	Day	29% 22% 27% 13% 7% 1	180
	11th to 20th	Day	28% 25% 27% 16% 4	180
	21st to end	Day	28% 21% 28% 18% 3 2	198
January	1st to 10th	Night	19% 16% 39% 22% 3	760
	11th to 20th	Night	26% 15% 28% 26% 4	760
	21st to end	Night	18% 17% 36% 26% 3	836
February	1st to 10th	Night	23% 16% 31% 29% 2	760
	11th to 20th	Night	22% 20% 37% 19% 2	743
	21st to end	Night	26% 16% 34% 21% 3	628
March	1st to 10th	Night	23% 18% 31% 24% 4	760
	11th to 20th	Night	25% 16% 31% 22% 5% 1	760
	21st to end	Night	23% 16% 34% 23% 4 1	836
April	1st to 10th	Night	23% 17% 33% 22% 5%	760
	11th to 20th	Night	17% 14% 36% 25% 8%	711
	21st to end	Night	25% 12% 29% 27% 7%	720
May	1st to 10th	Night	24% 10% 26% 30% 10%	545
	11th to 20th	Night	20% 8% 30% 32% 10% 1	354
	21st to end	Night	19% 7% 18% 39% 15% 2	389
June	1st to 10th	Night	17% 7% 21% 36% 19%	360
	11th to 20th	Night	18% 3 25% 40% 14% 1	360
	21st to end	Night	12% 3 22% 47% 16% 1	360
July	1st to 10th	Night	12% 3 19% 39% 24% 3	350
	11th to 20th	Night	11% 2 19% 41% 26% 2	348
	21st to end	Night	11% 4 16% 43% 25% 1	461
August	1st to 10th	Night	14% 2 13% 41% 29% 2	537
	11th to 20th	Night	16% 3 15% 33% 31% 2	639
	21st to end	Night	17% 2 17% 35% 27% 3	792
September	1st to 10th	Night	18% 4 20% 35% 20% 3	720
	11th to 20th	Night	15% 5% 16% 35% 24% 5%	720
	21st to end	Night	20% 4 19% 34% 20% 2	720
October	1st to 10th	Night	24% 6% 21% 28% 17% 4	720
	11th to 20th	Night	21% 9% 22% 35% 12% 1	720
	21st to end	Night	25% 10% 27% 28% 10%	792
November	1st to 10th	Night	16% 9% 31% 30% 13% 1	740
	11th to 20th	Night	20% 15% 27% 29% 8% 1	760
	21st to end	Night	18% 15% 29% 32% 7%	760
December	1st to 10th	Night	26% 13% 32% 23% 5% 1	760
	11th to 20th	Night	22% 12% 32% 28% 5%	760
	21st to end	Night	25% 10% 32% 30% 3	836

Page generated at 2024-04-07 09:28:15. Version ac07

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