Randolph State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Randolph State Park clear sky chart from 2005-11-06 to 2024-01-13.

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	10% 6% 3 5% 5% 3 4 4 5% 7% 48%	74713
	Night	10% 6% 2 5% 4 3 4 4 5% 7% 51%	75035
Transparency	Day	36% 5% 12% 26% 17% 3	74437
	Night	33% 5% 12% 27% 19% 4	74831
Seeing	Day	13% 9% 31% 29% 14% 3	14519
	Night	12% 9% 34% 33% 10% 1	24531

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	9% 8% 3 6% 5% 3 5% 4 5% 8% 45%	1707
	11th to 20th	Day	9% 8% 3 6% 5% 3 4 5% 4 7% 47%	1643
	21st to end	Day	9% 7% 5% 8% 6% 4 4 4 5% 6% 42%	1782
February	1st to 10th	Day	10% 11% 3 7% 5% 3 4 4 5% 6% 41%	1620
	11th to 20th	Day	9% 8% 3 6% 5% 3 5% 4 6% 8% 43%	1675
	21st to end	Day	8% 7% 3 7% 5% 3 4 5% 5% 7% 47%	1480
March	1st to 10th	Day	10% 6% 3 5% 5% 2 4 4 6% 7% 48%	1940
	11th to 20th	Day	18% 10% 3 4 4 2 3 4 4 5% 43%	1980
	21st to end	Day	16% 9% 3 7% 7% 3 4 4 5% 7% 35%	2178
April	1st to 10th	Day	13% 5% 3 6% 5% 2 3 4 5% 7% 47%	1988
	11th to 20th	Day	12% 7% 3 6% 5% 3 5% 5% 5% 6% 43%	2240
	21st to end	Day	18% 6% 3 5% 5% 3 4 4 5% 7% 40%	2340
May	1st to 10th	Day	15% 8% 4 6% 5% 3 4 5% 5% 6% 40%	2340
	11th to 20th	Day	14% 7% 2 6% 4 3 4 4 5% 7% 44%	2302
	21st to end	Day	15% 7% 3 5% 5% 4 6% 5% 6% 7% 36%	2531
June	1st to 10th	Day	7% 3 2 4 4 3 5% 4 5% 9% 56%	2340
	11th to 20th	Day	7% 3 2 4 4 3 6% 5% 6% 8% 52%	2340
	21st to end	Day	6% 3 2 4 4 3 5% 5% 6% 8% 54%	2340
July	1st to 10th	Day	8% 4 2 5% 5% 4 5% 6% 7% 8% 47%	2340
	11th to 20th	Day	4 3 2 4 5% 3 6% 5% 6% 9% 54%	2340
	21st to end	Day	7% 4 3 4 4 3 6% 6% 6% 10% 48%	2546
August	1st to 10th	Day	8% 4 2 4 5% 3 4 5% 6% 10% 48%	2328
	11th to 20th	Day	8% 4 2 4 5% 3 4 4 5% 7% 55%	2301
	21st to end	Day	7% 4 2 3 4 2 4 4 5% 8% 58%	2534
September	1st to 10th	Day	11% 4 2 3 4 2 3 4 5% 7% 55%	2021
	11th to 20th	Day	10% 4 2 4 5% 3 4 4 5% 7% 53%	1980
	21st to end	Day	9% 4 2 4 4 2 4 5% 4 5% 57%	1980
October	1st to 10th	Day	13% 5% 2 4 4 3 3 3 4 5% 53%	1877
	11th to 20th	Day	11% 4 2 4 3 2 3 3 4 5% 59%	1800
	21st to end	Day	12% 6% 2 5% 4 3 3 3 4 5% 53%	1980
November	1st to 10th	Day	7% 3 2 5% 3 3 4 4 5% 6% 58%	1709
	11th to 20th	Day	9% 6% 3 4 3 2 3 4 4 5% 57%	1710
	21st to end	Day	13% 6% 3 3 3 2 4 3 4 7% 52%	1710
December	1st to 10th	Day	8% 6% 3 6% 5% 3 5% 4 5% 7% 47%	1538
	11th to 20th	Day	9% 9% 3 7% 7% 3 3 3 4 6% 45%	2118
	21st to end	Day	14% 12% 5% 14% 6% 3 4 5% 4 6% 27%	3135
January	1st to 10th	Night	7% 7% 4 6% 5% 3 5% 4 5% 6% 48%	2458
	11th to 20th	Night	8% 9% 3 5% 4 2 4 4 5% 7% 47%	2379
	21st to end	Night	9% 7% 3 6% 5% 4 4 3 4 6% 49%	2574
February	1st to 10th	Night	10% 9% 4 6% 5% 3 4 4 5% 6% 43%	2340
	11th to 20th	Night	9% 7% 3 6% 5% 3 5% 5% 5% 8% 44%	2189
	21st to end	Night	8% 6% 2 7% 5% 3 4 4 4 5% 51%	1776
March	1st to 10th	Night	8% 7% 2 5% 4 3 4 3 4 7% 52%	2019
	11th to 20th	Night	14% 7% 3 5% 4 3 3 4 5% 6% 46%	1980
	21st to end	Night	17% 8% 4 7% 4 3 4 4 5% 7% 37%	2178
April	1st to 10th	Night	11% 5% 2 5% 4 2 3 3 5% 7% 53%	1972
	11th to 20th	Night	12% 7% 3 5% 5% 3 3 4 5% 7% 46%	1666
	21st to end	Night	14% 6% 2 4 4 3 4 4 5% 8% 45%	1620
May	1st to 10th	Night	15% 7% 2 7% 4 2 4 5% 5% 7% 40%	1620
	11th to 20th	Night	15% 5% 2 5% 4 3 4 4 4 7% 49%	1593
	21st to end	Night	12% 5% 3 4 4 3 4 4 5% 9% 47%	1745
June	1st to 10th	Night	5% 3 1 3 4 3 3 5% 6% 11% 57%	1620
	11th to 20th	Night	6% 3 1 4 4 2 5% 6% 5% 11% 54%	1620
	21st to end	Night	5% 2 1 3 3 3 3 5% 6% 10% 59%	1620
July	1st to 10th	Night	6% 3 1 4 4 3 5% 5% 5% 8% 54%	1620
	11th to 20th	Night	3 1 1 3 3 2 5% 5% 5% 10% 63%	1620
	21st to end	Night	5% 4 2 4 4 3 4 5% 7% 11% 52%	1772
August	1st to 10th	Night	4 2 2 5% 4 2 4 5% 7% 11% 55%	1611
	11th to 20th	Night	6% 3 2 4 5% 2 4 3 5% 8% 58%	1600
	21st to end	Night	6% 4 1 3 3 3 4 3 6% 7% 61%	1820
September	1st to 10th	Night	9% 3 2 3 3 2 3 3 4 7% 60%	1934
	11th to 20th	Night	10% 3 2 4 4 2 4 4 5% 6% 57%	1980
	21st to end	Night	8% 3 2 4 4 2 3 3 4 6% 61%	1980
October	1st to 10th	Night	12% 5% 2 4 4 2 3 4 5% 7% 52%	2063
	11th to 20th	Night	12% 5% 2 3 3 2 3 3 4 5% 59%	2160
	21st to end	Night	11% 6% 2 4 3 2 2 3 4 5% 55%	2376
November	1st to 10th	Night	6% 5% 1 4 3 2 3 3 4 7% 61%	2365
	11th to 20th	Night	8% 4 2 4 3 1 4 4 5% 6% 58%	2470
	21st to end	Night	11% 7% 2 3 4 2 3 4 4 6% 54%	2470
December	1st to 10th	Night	8% 5% 3 4 4 3 4 5% 5% 6% 52%	2628
	11th to 20th	Night	9% 8% 3 6% 4 2 3 4 5% 7% 50%	3065
	21st to end	Night	16% 13% 5% 9% 5% 2 3 3 3 5% 36%	4532

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	38% 4 13% 28% 14% 2	1708
	11th to 20th	Day	37% 5% 16% 26% 14% 1	1643
	21st to end	Day	43% 4 14% 25% 12% 1	1782
February	1st to 10th	Day	45% 5% 14% 22% 10% 4	1620
	11th to 20th	Day	39% 5% 13% 26% 13% 3	1684
	21st to end	Day	37% 5% 11% 24% 19% 3	1480
March	1st to 10th	Day	36% 5% 12% 23% 20% 4	1940
	11th to 20th	Day	45% 4 9% 23% 17% 3	1980
	21st to end	Day	49% 6% 13% 20% 9% 2	2178
April	1st to 10th	Day	37% 4 13% 25% 18% 3	1988
	11th to 20th	Day	41% 6% 12% 24% 16% 2	2240
	21st to end	Day	45% 5% 10% 26% 14% 1	2340
May	1st to 10th	Day	45% 6% 12% 21% 14% 2	2340
	11th to 20th	Day	41% 5% 14% 28% 12%	2306
	21st to end	Day	45% 6% 15% 22% 10% 2	2531
June	1st to 10th	Day	26% 7% 15% 35% 15% 2	2340
	11th to 20th	Day	29% 6% 14% 28% 21% 3	2340
	21st to end	Day	26% 6% 15% 30% 19% 4	2340
July	1st to 10th	Day	33% 7% 13% 25% 19% 3	2276
	11th to 20th	Day	25% 7% 14% 29% 19% 6%	2271
	21st to end	Day	28% 7% 14% 32% 18% 1	2405
August	1st to 10th	Day	30% 7% 19% 27% 14% 2	2314
	11th to 20th	Day	28% 5% 12% 31% 21% 3	2301
	21st to end	Day	26% 6% 11% 27% 23% 8%	2534
September	1st to 10th	Day	28% 5% 12% 27% 21% 7%	2021
	11th to 20th	Day	31% 4 10% 27% 23% 3	1980
	21st to end	Day	29% 4 9% 30% 25% 3	1980
October	1st to 10th	Day	34% 3 11% 25% 24% 2	1877
	11th to 20th	Day	29% 4 6% 28% 26% 7%	1800
	21st to end	Day	35% 3 10% 24% 21% 6%	1980
November	1st to 10th	Day	26% 5% 12% 30% 23% 5%	1709
	11th to 20th	Day	31% 3 10% 27% 26% 3	1710
	21st to end	Day	35% 3 11% 28% 21% 2	1710
December	1st to 10th	Day	36% 4 16% 28% 16% 1	1538
	11th to 20th	Day	41% 4 13% 28% 14% 1	2116
	21st to end	Day	58% 5% 9% 19% 8% 1	3135
January	1st to 10th	Night	37% 4 14% 26% 18% 1	2458
	11th to 20th	Night	37% 4 13% 27% 17% 2	2379
	21st to end	Night	37% 3 17% 26% 13% 3	2574
February	1st to 10th	Night	42% 5% 12% 22% 16% 4	2340
	11th to 20th	Night	39% 4 12% 28% 14% 3	2190
	21st to end	Night	35% 4 10% 25% 20% 7%	1776
March	1st to 10th	Night	34% 3 11% 27% 20% 5%	2019
	11th to 20th	Night	39% 4 11% 23% 18% 4	1980
	21st to end	Night	47% 5% 13% 20% 12% 3	2178
April	1st to 10th	Night	32% 4 12% 26% 23% 3	1972
	11th to 20th	Night	38% 5% 10% 27% 18% 3	1666
	21st to end	Night	38% 5% 12% 27% 18% 1	1620
May	1st to 10th	Night	43% 6% 13% 22% 15% 2	1620
	11th to 20th	Night	36% 5% 15% 27% 17% 1	1594
	21st to end	Night	35% 7% 20% 24% 12% 2	1746
June	1st to 10th	Night	22% 6% 17% 34% 18% 3	1620
	11th to 20th	Night	24% 6% 15% 32% 17% 5%	1620
	21st to end	Night	20% 6% 15% 34% 20% 5%	1620
July	1st to 10th	Night	26% 6% 17% 29% 18% 5%	1575
	11th to 20th	Night	17% 6% 15% 29% 27% 5%	1566
	21st to end	Night	25% 6% 13% 36% 19% 2	1673
August	1st to 10th	Night	23% 7% 21% 31% 16% 2	1601
	11th to 20th	Night	25% 5% 12% 34% 21% 3	1600
	21st to end	Night	22% 5% 12% 28% 25% 8%	1820
September	1st to 10th	Night	25% 4 12% 30% 22% 8%	1934
	11th to 20th	Night	28% 5% 9% 28% 25% 5%	1980
	21st to end	Night	26% 3 9% 27% 31% 5%	1980
October	1st to 10th	Night	32% 5% 10% 26% 24% 4	2063
	11th to 20th	Night	29% 4 6% 29% 24% 9%	2160
	21st to end	Night	31% 4 10% 23% 26% 6%	2376
November	1st to 10th	Night	24% 3 10% 28% 26% 8%	2365
	11th to 20th	Night	27% 4 10% 30% 24% 4	2470
	21st to end	Night	33% 3 10% 28% 22% 4	2470
December	1st to 10th	Night	32% 5% 15% 29% 19% 1	2628
	11th to 20th	Night	34% 4 11% 33% 17% 1	3066
	21st to end	Night	53% 4 9% 23% 10% 2	4532

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	14% 15% 41% 19% 9% 1	270
	11th to 20th	Day	19% 17% 40% 20% 4	248
	21st to end	Day	11% 14% 48% 23% 3	264
February	1st to 10th	Day	15% 21% 44% 15% 4	240
	11th to 20th	Day	17% 13% 46% 18% 5%	240
	21st to end	Day	14% 24% 38% 21% 3 1	198
March	1st to 10th	Day	15% 17% 46% 17% 5%	240
	11th to 20th	Day	27% 12% 36% 18% 6% 1	240
	21st to end	Day	27% 17% 41% 11% 4	264
April	1st to 10th	Day	19% 17% 40% 20% 4	248
	11th to 20th	Day	18% 18% 36% 23% 5%	518
	21st to end	Day	21% 19% 31% 19% 9% 2	600
May	1st to 10th	Day	17% 14% 36% 23% 8% 1	603
	11th to 20th	Day	19% 10% 29% 28% 12% 2	625
	21st to end	Day	18% 6% 32% 27% 15% 2	679
June	1st to 10th	Day	5% 5% 22% 37% 24% 6%	630
	11th to 20th	Day	7% 4 32% 35% 18% 3	630
	21st to end	Day	7% 5% 37% 37% 12% 2	630
July	1st to 10th	Day	10% 2 16% 37% 29% 6%	621
	11th to 20th	Day	5% 2 19% 40% 26% 7%	618
	21st to end	Day	8% 2 17% 41% 28% 4	684
August	1st to 10th	Day	8% 2 18% 42% 27% 3	626
	11th to 20th	Day	7% 4 18% 44% 22% 4	615
	21st to end	Day	10% 2 19% 35% 28% 6%	653
September	1st to 10th	Day	11% 3 26% 39% 16% 5%	311
	11th to 20th	Day	6% 5% 29% 38% 18% 5%	270
	21st to end	Day	14% 6% 34% 30% 13% 3	270
October	1st to 10th	Day	19% 11% 26% 27% 12% 4	270
	11th to 20th	Day	9% 17% 43% 23% 7% 1	270
	21st to end	Day	20% 15% 36% 20% 7% 1	297
November	1st to 10th	Day	13% 14% 40% 24% 7% 1	270
	11th to 20th	Day	17% 16% 37% 24% 5% 1	270
	21st to end	Day	22% 12% 37% 21% 7% 1	270
December	1st to 10th	Day	10% 12% 42% 26% 8% 2	270
	11th to 20th	Day	15% 17% 37% 23% 8%	270
	21st to end	Day	20% 16% 43% 19% 1	297
January	1st to 10th	Night	11% 13% 37% 31% 7%	950
	11th to 20th	Night	13% 12% 38% 30% 8%	915
	21st to end	Night	13% 10% 43% 30% 4	990
February	1st to 10th	Night	16% 10% 43% 26% 3	900
	11th to 20th	Night	13% 14% 40% 29% 3	795
	21st to end	Night	13% 16% 41% 24% 5% 1	592
March	1st to 10th	Night	13% 16% 41% 25% 5%	579
	11th to 20th	Night	17% 13% 35% 28% 7%	540
	21st to end	Night	21% 13% 39% 22% 5% 1	594
April	1st to 10th	Night	14% 12% 44% 24% 5%	540
	11th to 20th	Night	18% 14% 38% 26% 3	533
	21st to end	Night	18% 9% 39% 26% 7% 1	540
May	1st to 10th	Night	17% 10% 34% 31% 8% 1	540
	11th to 20th	Night	17% 7% 33% 32% 10% 1	531
	21st to end	Night	14% 7% 29% 35% 14% 1	584
June	1st to 10th	Night	6% 4 27% 41% 21% 1	540
	11th to 20th	Night	6% 3 33% 41% 17% 1	540
	21st to end	Night	6% 3 34% 46% 11% 1	540
July	1st to 10th	Night	7% 2 18% 46% 26% 1	525
	11th to 20th	Night	3 1 20% 50% 24% 2	522
	21st to end	Night	6% 1 16% 51% 25% 2	591
August	1st to 10th	Night	5% 2 20% 47% 26% 1	537
	11th to 20th	Night	7% 3 15% 53% 20% 2	534
	21st to end	Night	7% 3 18% 45% 25% 3	594
September	1st to 10th	Night	9% 4 26% 43% 16% 2	540
	11th to 20th	Night	11% 2 26% 40% 19% 2	540
	21st to end	Night	9% 4 33% 37% 16% 1	540
October	1st to 10th	Night	14% 7% 30% 32% 15% 2	623
	11th to 20th	Night	15% 10% 40% 27% 8%	720
	21st to end	Night	16% 12% 31% 33% 8% 1	792
November	1st to 10th	Night	9% 10% 35% 36% 9% 1	885
	11th to 20th	Night	11% 12% 41% 29% 6%	950
	21st to end	Night	15% 12% 34% 31% 8%	950
December	1st to 10th	Night	12% 11% 39% 31% 6%	950
	11th to 20th	Night	17% 11% 38% 29% 5%	950
	21st to end	Night	17% 14% 36% 29% 4	1045

Page generated at 2024-01-10 18:35:22. Version ac07

Copyright 2024 Attilla Danko