Suwannee Skies Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Suwannee Skies Observatory clear sky chart from 2005-11-06 to 2024-02-15.

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% 5% 2 6% 6% 4 6% 6% 7% 9% 40%	78768
	Night	10% 6% 3 5% 5% 3 5% 5% 6% 9% 44%	80315
Transparency	Day	38% 9% 14% 17% 15% 7%	78491
	Night	36% 8% 15% 19% 16% 7%	80111
Seeing	Day	10% 7% 20% 25% 23% 14%	14229
	Night	11% 5% 21% 32% 25% 6%	24354

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	15% 7% 3 5% 3 2 3 4 5% 7% 46%	2836
	11th to 20th	Day	18% 9% 3 6% 5% 3 4 4 5% 6% 39%	2840
	21st to end	Day	11% 5% 2 5% 5% 2 5% 4 7% 8% 45%	3356
February	1st to 10th	Day	17% 6% 3 5% 5% 3 3 3 5% 7% 44%	1900
	11th to 20th	Day	13% 5% 2 4 5% 2 3 4 5% 5% 52%	1788
	21st to end	Day	13% 6% 3 5% 5% 3 4 4 4 6% 48%	1480
March	1st to 10th	Day	8% 4 1 3 4 2 4 5% 6% 10% 54%	1964
	11th to 20th	Day	9% 5% 2 4 3 3 4 5% 6% 8% 51%	1980
	21st to end	Day	8% 5% 2 4 5% 3 4 4 6% 7% 52%	2178
April	1st to 10th	Day	8% 4 2 4 4 4 4 5% 5% 10% 49%	1980
	11th to 20th	Day	11% 5% 3 6% 5% 3 4 5% 5% 8% 45%	1956
	21st to end	Day	5% 3 1 4 4 3 5% 6% 6% 8% 55%	2280
May	1st to 10th	Day	5% 3 1 3 4 3 4 5% 6% 10% 57%	2340
	11th to 20th	Day	7% 4 2 5% 6% 4 6% 6% 7% 10% 42%	2301
	21st to end	Day	7% 5% 2 5% 6% 5% 7% 6% 6% 8% 42%	2531
June	1st to 10th	Day	10% 6% 3 6% 7% 5% 8% 8% 8% 10% 29%	2340
	11th to 20th	Day	5% 5% 3 6% 8% 6% 8% 9% 9% 12% 30%	2340
	21st to end	Day	8% 5% 2 7% 7% 5% 8% 9% 8% 11% 30%	2340
July	1st to 10th	Day	9% 6% 2 6% 7% 5% 8% 9% 9% 13% 26%	2340
	11th to 20th	Day	8% 5% 3 9% 9% 5% 9% 8% 10% 11% 22%	2340
	21st to end	Day	7% 6% 3 7% 8% 6% 9% 9% 8% 13% 24%	2547
August	1st to 10th	Day	11% 4 3 6% 6% 5% 8% 8% 10% 13% 26%	2319
	11th to 20th	Day	10% 6% 3 8% 10% 6% 8% 9% 10% 10% 19%	2125
	21st to end	Day	11% 6% 3 9% 9% 5% 8% 9% 7% 10% 23%	2249
September	1st to 10th	Day	10% 7% 4 9% 9% 6% 9% 8% 8% 10% 22%	1980
	11th to 20th	Day	10% 6% 4 9% 8% 6% 7% 7% 7% 9% 28%	1980
	21st to end	Day	9% 6% 3 7% 7% 4 5% 5% 6% 7% 38%	1980
October	1st to 10th	Day	12% 6% 2 5% 6% 4 5% 5% 6% 8% 40%	1980
	11th to 20th	Day	5% 4 2 4 5% 2 4 5% 5% 8% 56%	1859
	21st to end	Day	7% 4 2 5% 5% 4 5% 5% 6% 7% 50%	1980
November	1st to 10th	Day	8% 4 2 4 4 3 5% 4 6% 8% 52%	1857
	11th to 20th	Day	10% 6% 3 5% 5% 3 5% 4 4 7% 49%	1805
	21st to end	Day	11% 6% 2 4 5% 3 5% 4 4 8% 48%	1710
December	1st to 10th	Day	9% 5% 2 6% 5% 4 5% 5% 5% 8% 47%	1710
	11th to 20th	Day	14% 5% 3 6% 4 3 3 4 6% 7% 46%	2153
	21st to end	Day	18% 8% 3 5% 5% 3 4 4 4 6% 41%	3124
January	1st to 10th	Night	15% 8% 3 4 4 2 4 4 4 8% 42%	4109
	11th to 20th	Night	13% 8% 3 7% 6% 3 4 5% 5% 7% 38%	4120
	21st to end	Night	15% 7% 3 6% 5% 3 4 5% 5% 6% 42%	4296
February	1st to 10th	Night	13% 6% 2 5% 6% 3 4 5% 4 6% 47%	2280
	11th to 20th	Night	11% 6% 3 4 4 3 4 4 5% 6% 49%	2153
	21st to end	Night	12% 7% 3 5% 4 2 4 3 5% 7% 47%	1776
March	1st to 10th	Night	9% 5% 2 4 4 2 3 4 5% 8% 56%	1994
	11th to 20th	Night	9% 6% 2 5% 4 3 4 4 5% 9% 48%	1980
	21st to end	Night	8% 6% 2 4 4 2 4 4 5% 7% 55%	2178
April	1st to 10th	Night	10% 5% 3 4 5% 2 4 5% 5% 7% 50%	1980
	11th to 20th	Night	8% 5% 3 4 4 3 4 6% 6% 7% 50%	1953
	21st to end	Night	6% 3 2 4 3 3 4 3 5% 8% 59%	1691
May	1st to 10th	Night	5% 2 2 3 4 3 4 3 5% 9% 61%	1620
	11th to 20th	Night	4 4 3 4 5% 3 5% 4 7% 11% 50%	1592
	21st to end	Night	4 4 2 4 5% 3 5% 6% 6% 11% 51%	1744
June	1st to 10th	Night	10% 6% 2 6% 6% 4 6% 6% 7% 10% 37%	1620
	11th to 20th	Night	4 3 3 4 6% 3 6% 7% 9% 15% 39%	1620
	21st to end	Night	6% 5% 3 4 6% 4 6% 6% 9% 13% 39%	1620
July	1st to 10th	Night	6% 4 2 4 6% 5% 6% 7% 10% 15% 35%	1620
	11th to 20th	Night	3 4 2 7% 8% 5% 6% 8% 10% 15% 33%	1620
	21st to end	Night	3 4 2 5% 7% 5% 8% 9% 9% 13% 36%	1771
August	1st to 10th	Night	7% 5% 2 5% 6% 4 6% 7% 9% 13% 36%	1614
	11th to 20th	Night	5% 4 2 6% 6% 4 7% 7% 9% 15% 35%	1776
	21st to end	Night	7% 6% 3 8% 8% 4 6% 8% 8% 9% 33%	2088
September	1st to 10th	Night	7% 5% 3 8% 9% 5% 7% 7% 8% 12% 28%	1980
	11th to 20th	Night	10% 7% 3 7% 6% 4 6% 7% 8% 11% 30%	1980
	21st to end	Night	10% 6% 3 5% 6% 3 5% 5% 7% 9% 41%	1980
October	1st to 10th	Night	10% 6% 3 5% 5% 4 5% 4 5% 7% 46%	1980
	11th to 20th	Night	7% 4 2 4 5% 2 4 3 5% 6% 58%	2099
	21st to end	Night	7% 4 2 5% 6% 2 4 4 6% 7% 52%	2376
November	1st to 10th	Night	8% 4 2 4 5% 3 4 5% 5% 8% 52%	2221
	11th to 20th	Night	10% 5% 2 6% 4 2 4 4 4 6% 52%	2370
	21st to end	Night	10% 6% 3 5% 5% 2 5% 4 5% 7% 48%	2470
December	1st to 10th	Night	12% 6% 3 4 4 2 4 5% 6% 8% 46%	2470
	11th to 20th	Night	14% 6% 3 5% 4 3 3 4 4 7% 47%	3042
	21st to end	Night	16% 7% 3 5% 5% 3 4 4 5% 7% 40%	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 8% 17% 20% 13%	2837
	11th to 20th	Day	46% 4 6% 13% 17% 13%	2840
	21st to end	Day	34% 7% 12% 18% 17% 12%	3356
February	1st to 10th	Day	41% 4 9% 14% 19% 12%	1900
	11th to 20th	Day	33% 4 8% 17% 25% 12%	1798
	21st to end	Day	36% 5% 10% 16% 21% 12%	1480
March	1st to 10th	Day	26% 6% 11% 21% 25% 11%	1964
	11th to 20th	Day	31% 6% 14% 21% 16% 11%	1980
	21st to end	Day	31% 5% 11% 23% 19% 10%	2178
April	1st to 10th	Day	31% 6% 15% 18% 19% 12%	1980
	11th to 20th	Day	37% 6% 9% 21% 19% 9%	1956
	21st to end	Day	25% 7% 13% 24% 22% 10%	2280
May	1st to 10th	Day	23% 7% 12% 24% 25% 9%	2340
	11th to 20th	Day	33% 9% 18% 20% 16% 3	2305
	21st to end	Day	37% 9% 13% 22% 17% 2	2531
June	1st to 10th	Day	44% 12% 19% 18% 7%	2340
	11th to 20th	Day	40% 15% 20% 20% 5%	2340
	21st to end	Day	43% 15% 20% 15% 6% 1	2340
July	1st to 10th	Day	42% 17% 26% 14% 1	2275
	11th to 20th	Day	49% 16% 23% 9% 2	2271
	21st to end	Day	44% 14% 26% 14% 2	2405
August	1st to 10th	Day	41% 17% 26% 14% 2	2306
	11th to 20th	Day	51% 18% 23% 7% 2	2125
	21st to end	Day	52% 13% 19% 12% 3	2249
September	1st to 10th	Day	53% 13% 16% 11% 6% 1	1980
	11th to 20th	Day	49% 11% 18% 13% 7% 1	1980
	21st to end	Day	41% 8% 13% 18% 14% 5%	1980
October	1st to 10th	Day	40% 7% 11% 16% 14% 11%	1980
	11th to 20th	Day	26% 6% 9% 23% 29% 8%	1859
	21st to end	Day	31% 6% 10% 14% 25% 14%	1980
November	1st to 10th	Day	29% 5% 12% 19% 20% 15%	1857
	11th to 20th	Day	34% 5% 8% 18% 24% 10%	1805
	21st to end	Day	35% 4 9% 21% 23% 7%	1710
December	1st to 10th	Day	35% 6% 12% 23% 19% 7%	1710
	11th to 20th	Day	37% 5% 10% 18% 20% 10%	2150
	21st to end	Day	44% 4 6% 21% 17% 7%	3124
January	1st to 10th	Night	41% 4 8% 15% 19% 14%	4109
	11th to 20th	Night	45% 4 6% 16% 20% 8%	4120
	21st to end	Night	42% 6% 10% 12% 19% 10%	4296
February	1st to 10th	Night	37% 5% 9% 16% 21% 12%	2280
	11th to 20th	Night	36% 5% 8% 18% 21% 12%	2154
	21st to end	Night	37% 5% 11% 17% 20% 11%	1776
March	1st to 10th	Night	28% 5% 11% 23% 21% 12%	1994
	11th to 20th	Night	33% 6% 14% 21% 16% 10%	1980
	21st to end	Night	29% 6% 12% 25% 19% 10%	2178
April	1st to 10th	Night	33% 6% 14% 18% 18% 11%	1980
	11th to 20th	Night	31% 7% 10% 24% 21% 7%	1953
	21st to end	Night	23% 5% 12% 29% 22% 8%	1691
May	1st to 10th	Night	21% 6% 11% 30% 23% 9%	1620
	11th to 20th	Night	27% 9% 20% 24% 15% 4	1593
	21st to end	Night	26% 9% 18% 23% 23% 2	1745
June	1st to 10th	Night	39% 9% 20% 25% 6%	1620
	11th to 20th	Night	28% 15% 28% 24% 5%	1620
	21st to end	Night	35% 12% 26% 20% 6% 1	1620
July	1st to 10th	Night	34% 18% 30% 15% 3	1575
	11th to 20th	Night	36% 19% 29% 14% 2	1566
	21st to end	Night	32% 16% 33% 15% 3	1672
August	1st to 10th	Night	34% 15% 32% 16% 3	1603
	11th to 20th	Night	33% 17% 36% 12% 2	1776
	21st to end	Night	43% 16% 21% 17% 3	2088
September	1st to 10th	Night	44% 15% 21% 13% 5% 1	1980
	11th to 20th	Night	45% 13% 20% 15% 6% 1	1980
	21st to end	Night	37% 10% 17% 18% 14% 5%	1980
October	1st to 10th	Night	36% 8% 12% 17% 15% 12%	1980
	11th to 20th	Night	27% 5% 10% 22% 28% 8%	2099
	21st to end	Night	30% 5% 10% 16% 24% 14%	2376
November	1st to 10th	Night	30% 5% 11% 21% 20% 14%	2221
	11th to 20th	Night	33% 4 8% 19% 23% 14%	2370
	21st to end	Night	36% 5% 10% 19% 20% 10%	2470
December	1st to 10th	Night	35% 5% 12% 25% 15% 7%	2470
	11th to 20th	Night	38% 5% 10% 16% 21% 10%	3044
	21st to end	Night	43% 5% 9% 21% 17% 5%	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	13% 14% 50% 17% 6% 1	270
	11th to 20th	Day	10% 16% 42% 19% 10% 1	270
	21st to end	Day	19% 19% 44% 14% 4	297
February	1st to 10th	Day	17% 14% 38% 23% 7% 1	270
	11th to 20th	Day	15% 17% 35% 24% 8% 1	252
	21st to end	Day	13% 12% 43% 21% 9% 1	198
March	1st to 10th	Day	9% 16% 32% 28% 14% 1	404
	11th to 20th	Day	15% 12% 34% 23% 15% 2	420
	21st to end	Day	9% 13% 32% 29% 15% 2	462
April	1st to 10th	Day	12% 14% 29% 25% 18% 1	420
	11th to 20th	Day	13% 10% 29% 29% 17% 2	412
	21st to end	Day	6% 5% 27% 33% 21% 7%	420
May	1st to 10th	Day	7% 8% 22% 31% 20% 12%	423
	11th to 20th	Day	6% 2 15% 34% 26% 16%	447
	21st to end	Day	9% 3 9% 24% 34% 21%	485
June	1st to 10th	Day	12% 2 10% 25% 32% 20%	450
	11th to 20th	Day	8% 4 11% 21% 31% 27%	450
	21st to end	Day	7% 1 4 23% 32% 33%	450
July	1st to 10th	Day	7% 2 6% 16% 30% 40%	445
	11th to 20th	Day	7% 1 2 15% 34% 42%	444
	21st to end	Day	7% 2 4 21% 35% 31%	488
August	1st to 10th	Day	11% 2 4 17% 33% 33%	446
	11th to 20th	Day	10% 2 3 14% 33% 38%	439
	21st to end	Day	11% 3 4 21% 33% 29%	495
September	1st to 10th	Day	10% 2 8% 22% 30% 28%	450
	11th to 20th	Day	10% 4 7% 30% 31% 19%	450
	21st to end	Day	10% 2 9% 27% 32% 19%	450
October	1st to 10th	Day	12% 4 24% 31% 21% 9%	450
	11th to 20th	Day	6% 4 19% 35% 28% 8%	450
	21st to end	Day	9% 5% 23% 37% 20% 5%	495
November	1st to 10th	Day	13% 4 23% 36% 20% 4	455
	11th to 20th	Day	15% 7% 30% 31% 14% 3	365
	21st to end	Day	10% 7% 41% 30% 11%	270
December	1st to 10th	Day	9% 14% 36% 23% 15% 3	270
	11th to 20th	Day	15% 14% 35% 26% 9% 1	270
	21st to end	Day	15% 11% 31% 29% 12% 1	297
January	1st to 10th	Night	17% 12% 31% 30% 9% 1	760
	11th to 20th	Night	11% 9% 28% 36% 14% 1	760
	21st to end	Night	18% 11% 34% 29% 6%	836
February	1st to 10th	Night	16% 8% 30% 33% 12%	760
	11th to 20th	Night	14% 10% 33% 33% 9% 1	722
	21st to end	Night	15% 8% 31% 41% 6%	592
March	1st to 10th	Night	10% 9% 33% 37% 10%	720
	11th to 20th	Night	13% 7% 30% 34% 16%	720
	21st to end	Night	10% 7% 31% 37% 14% 1	792
April	1st to 10th	Night	12% 8% 29% 35% 17% 1	720
	11th to 20th	Night	10% 8% 32% 35% 15% 1	711
	21st to end	Night	6% 4 26% 40% 23% 2	567
May	1st to 10th	Night	6% 2 21% 47% 22% 2	540
	11th to 20th	Night	6% 2 18% 39% 31% 4	531
	21st to end	Night	5% 1 10% 35% 40% 8%	584
June	1st to 10th	Night	11% 2 9% 33% 37% 9%	540
	11th to 20th	Night	5% 1 6% 28% 41% 19%	540
	21st to end	Night	8% 1 5% 20% 46% 19%	540
July	1st to 10th	Night	6% 2 4 17% 43% 28%	525
	11th to 20th	Night	5% 1 12% 52% 29%	522
	21st to end	Night	4 1 3 15% 57% 21%	591
August	1st to 10th	Night	7% 1 2 16% 51% 21%	537
	11th to 20th	Night	7% 1 2 12% 52% 26%	534
	21st to end	Night	9% 2 5% 24% 42% 19%	702
September	1st to 10th	Night	9% 2 7% 23% 43% 16%	720
	11th to 20th	Night	12% 4 9% 31% 34% 10%	720
	21st to end	Night	13% 3 11% 30% 36% 7%	720
October	1st to 10th	Night	12% 4 19% 38% 24% 3	720
	11th to 20th	Night	8% 3 20% 39% 28% 2	720
	21st to end	Night	9% 3 23% 39% 23% 2	792
November	1st to 10th	Night	10% 4 28% 37% 20% 1	740
	11th to 20th	Night	12% 6% 27% 39% 14% 2	760
	21st to end	Night	13% 6% 28% 39% 13% 1	760
December	1st to 10th	Night	14% 6% 26% 34% 18% 1	760
	11th to 20th	Night	13% 11% 26% 35% 16%	760
	21st to end	Night	15% 7% 29% 35% 14%	836

Page generated at 2024-02-12 06:35:35. Version ac07

Copyright 2024 Attilla Danko