Sarasota
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Sarasota clear sky chart from 2005-11-06 to 2026-09-14.

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	6% 4 2 6% 5% 5% 6% 5% 8% 11% 42%	148422
	Night	7% 5% 2 7% 5% 5% 5% 5% 7% 10% 43%	142634
Transparency	Day	33% 11% 20% 20% 12% 4	152195
	Night	34% 10% 18% 20% 13% 5%	146933
Seeing	Day	7% 4 18% 27% 26% 17%	18014
	Night	8% 3 17% 33% 29% 10%	28011

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	6% 5% 2 5% 3 3 4 4 6% 8% 54%	5258
	11th to 20th	Day	18% 9% 3 8% 4 4 5% 3 5% 7% 34%	5280
	21st to end	Day	13% 5% 2 5% 4 3 3 3 6% 8% 47%	6392
February	1st to 10th	Day	9% 5% 2 6% 3 4 4 4 7% 7% 49%	2100
	11th to 20th	Day	5% 4 2 4 3 3 4 4 6% 8% 57%	2048
	21st to end	Day	7% 4 2 5% 4 4 3 4 5% 8% 55%	1788
March	1st to 10th	Day	6% 4 2 7% 4 5% 5% 4 6% 8% 49%	5045
	11th to 20th	Day	4 3 1 4 3 3 3 3 6% 9% 61%	5090
	21st to end	Day	6% 4 2 5% 4 4 4 4 6% 9% 53%	5586
April	1st to 10th	Day	5% 3 2 5% 4 3 4 5% 8% 10% 52%	2310
	11th to 20th	Day	6% 4 2 5% 3 5% 5% 4 6% 8% 52%	2286
	21st to end	Day	4 2 1 4 3 4 5% 5% 6% 10% 56%	2469
May	1st to 10th	Day	2 2 1 4 3 3 4 4 7% 11% 57%	7616
	11th to 20th	Day	7% 4 2 5% 4 4 5% 4 7% 10% 50%	7626
	21st to end	Day	3 3 1 4 4 4 5% 4 8% 14% 50%	8391
June	1st to 10th	Day	9% 7% 3 8% 7% 6% 6% 5% 8% 12% 29%	2730
	11th to 20th	Day	6% 5% 2 7% 6% 7% 8% 7% 10% 12% 30%	2730
	21st to end	Day	7% 6% 2 7% 6% 6% 8% 8% 10% 11% 28%	2730
July	1st to 10th	Day	4 4 2 7% 6% 8% 10% 8% 12% 17% 23%	7680
	11th to 20th	Day	3 4 2 9% 8% 8% 10% 8% 12% 14% 23%	7680
	21st to end	Day	3 4 2 7% 6% 8% 9% 7% 11% 15% 28%	8340
August	1st to 10th	Day	6% 5% 3 9% 7% 8% 8% 7% 10% 13% 24%	5857
	11th to 20th	Day	3 2 2 5% 5% 6% 7% 7% 9% 12% 43%	5463
	21st to end	Day	5% 3 2 8% 7% 7% 9% 8% 11% 14% 26%	5566
September	1st to 10th	Day	7% 6% 2 7% 6% 7% 10% 7% 10% 12% 25%	2310
	11th to 20th	Day	9% 6% 2 7% 6% 7% 8% 7% 10% 11% 26%	2233
	21st to end	Day	6% 5% 3 7% 7% 7% 6% 6% 9% 13% 33%	2200
October	1st to 10th	Day	9% 6% 3 9% 6% 6% 6% 5% 7% 10% 36%	2200
	11th to 20th	Day	5% 4 2 5% 5% 5% 5% 4 7% 9% 50%	2060
	21st to end	Day	7% 5% 2 6% 4 4 4 4 6% 8% 50%	2200
November	1st to 10th	Day	6% 4 2 4 4 5% 4 4 6% 8% 51%	2057
	11th to 20th	Day	7% 5% 2 6% 5% 4 4 4 6% 7% 50%	2100
	21st to end	Day	7% 5% 1 5% 4 4 5% 4 6% 8% 50%	1953
December	1st to 10th	Day	4 3 1 4 3 4 4 3 5% 9% 61%	3020
	11th to 20th	Day	8% 6% 2 7% 5% 4 5% 4 6% 8% 47%	3463
	21st to end	Day	10% 7% 3 9% 6% 5% 5% 4 5% 8% 38%	4565
January	1st to 10th	Night	7% 5% 2 6% 4 4 4 3 6% 8% 52%	7635
	11th to 20th	Night	16% 10% 3 9% 5% 4 4 3 5% 7% 32%	7680
	21st to end	Night	11% 5% 2 6% 4 4 4 4 6% 7% 46%	7772
February	1st to 10th	Night	9% 6% 2 6% 4 4 4 3 6% 7% 49%	2520
	11th to 20th	Night	8% 6% 2 5% 4 4 4 3 5% 7% 52%	2458
	21st to end	Night	5% 5% 2 4 4 4 4 4 7% 8% 52%	2016
March	1st to 10th	Night	7% 6% 2 6% 4 4 4 4 5% 8% 50%	5028
	11th to 20th	Night	4 3 1 4 4 3 4 4 6% 10% 57%	5090
	21st to end	Night	8% 5% 2 6% 3 3 4 4 5% 7% 51%	5588
April	1st to 10th	Night	5% 4 2 4 4 4 4 4 7% 9% 53%	2310
	11th to 20th	Night	5% 4 1 5% 3 4 5% 4 7% 9% 53%	2283
	21st to end	Night	4 3 1 4 4 4 4 4 6% 9% 56%	2165
May	1st to 10th	Night	4 4 1 5% 4 5% 5% 4 7% 11% 51%	5237
	11th to 20th	Night	6% 5% 2 7% 4 4 4 4 6% 8% 50%	5234
	21st to end	Night	5% 3 2 6% 4 5% 6% 4 7% 10% 48%	5761
June	1st to 10th	Night	10% 6% 3 6% 6% 6% 5% 4 7% 10% 37%	1890
	11th to 20th	Night	6% 4 2 6% 4 7% 6% 5% 11% 12% 37%	1890
	21st to end	Night	6% 6% 2 7% 5% 5% 6% 7% 10% 14% 34%	1890
July	1st to 10th	Night	5% 5% 3 8% 6% 7% 8% 7% 11% 14% 24%	5278
	11th to 20th	Night	4 4 3 8% 7% 7% 8% 7% 11% 14% 26%	5277
	21st to end	Night	4 6% 3 10% 7% 7% 9% 7% 11% 13% 25%	5736
August	1st to 10th	Night	4 5% 3 9% 6% 7% 8% 6% 10% 13% 29%	4272
	11th to 20th	Night	2 3 1 5% 4 5% 6% 6% 10% 15% 45%	4560
	21st to end	Night	5% 4 2 9% 6% 8% 8% 7% 11% 15% 25%	5533
September	1st to 10th	Night	5% 5% 3 8% 6% 7% 8% 6% 11% 13% 28%	2310
	11th to 20th	Night	8% 7% 2 8% 7% 7% 7% 6% 8% 11% 30%	2234
	21st to end	Night	7% 7% 3 9% 6% 6% 6% 6% 9% 10% 32%	2200
October	1st to 10th	Night	9% 5% 3 7% 5% 5% 6% 4 7% 9% 39%	2200
	11th to 20th	Night	6% 6% 2 6% 4 4 4 4 6% 8% 51%	2338
	21st to end	Night	8% 5% 2 6% 4 4 4 4 6% 9% 49%	2640
November	1st to 10th	Night	6% 4 2 6% 5% 4 5% 3 6% 7% 51%	2461
	11th to 20th	Night	8% 5% 2 5% 4 4 4 3 6% 8% 50%	2520
	21st to end	Night	7% 5% 2 6% 5% 4 4 4 6% 9% 48%	2663
December	1st to 10th	Night	4 3 1 4 3 3 3 3 5% 8% 61%	4380
	11th to 20th	Night	10% 7% 2 5% 4 4 4 4 5% 7% 49%	4952
	21st to end	Night	11% 8% 3 8% 5% 5% 5% 4 6% 8% 36%	6633

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	26% 6% 11% 25% 26% 6%	5259
	11th to 20th	Day	49% 5% 8% 17% 14% 8%	5280
	21st to end	Day	34% 5% 10% 27% 15% 9%	6392
February	1st to 10th	Day	32% 7% 10% 20% 20% 11%	2100
	11th to 20th	Day	24% 6% 12% 24% 24% 9%	2058
	21st to end	Day	28% 5% 13% 19% 27% 9%	1788
March	1st to 10th	Day	31% 8% 12% 22% 21% 6%	5045
	11th to 20th	Day	20% 7% 13% 23% 20% 17%	5090
	21st to end	Day	26% 5% 11% 29% 22% 6%	5586
April	1st to 10th	Day	24% 8% 19% 26% 17% 6%	2310
	11th to 20th	Day	28% 7% 14% 18% 24% 9%	2286
	21st to end	Day	21% 8% 15% 25% 26% 5%	2469
May	1st to 10th	Day	18% 8% 26% 31% 14% 2	7651
	11th to 20th	Day	28% 10% 21% 25% 15% 1	7630
	21st to end	Day	22% 12% 28% 28% 10%	8405
June	1st to 10th	Day	43% 13% 21% 18% 4	2730
	11th to 20th	Day	40% 14% 26% 18% 3	2730
	21st to end	Day	41% 17% 26% 13% 2	2730
July	1st to 10th	Day	40% 21% 33% 5% 1	7615
	11th to 20th	Day	42% 19% 31% 8%	7611
	21st to end	Day	37% 19% 28% 14% 1	8156
August	1st to 10th	Day	44% 17% 29% 8% 2	5844
	11th to 20th	Day	27% 16% 28% 24% 4	5499
	21st to end	Day	39% 20% 30% 10% 1	5566
September	1st to 10th	Day	45% 19% 24% 11% 1	2310
	11th to 20th	Day	44% 17% 22% 14% 4	2233
	21st to end	Day	39% 15% 18% 18% 9% 2	2200
October	1st to 10th	Day	51% 13% 15% 10% 8% 4	3590
	11th to 20th	Day	25% 8% 11% 23% 30% 4	3339
	21st to end	Day	27% 6% 9% 26% 25% 8%	3538
November	1st to 10th	Day	29% 7% 12% 22% 20% 11%	2057
	11th to 20th	Day	32% 5% 10% 22% 22% 9%	2100
	21st to end	Day	29% 6% 13% 22% 19% 10%	1953
December	1st to 10th	Day	21% 6% 14% 29% 21% 8%	3020
	11th to 20th	Day	34% 6% 10% 20% 20% 10%	3460
	21st to end	Day	41% 8% 12% 21% 16% 3	4565
January	1st to 10th	Night	29% 5% 10% 26% 24% 5%	7636
	11th to 20th	Night	50% 5% 10% 15% 13% 7%	7680
	21st to end	Night	36% 6% 11% 23% 15% 9%	7772
February	1st to 10th	Night	33% 6% 10% 20% 22% 10%	2520
	11th to 20th	Night	31% 4 11% 23% 22% 9%	2459
	21st to end	Night	27% 7% 12% 20% 27% 7%	2016
March	1st to 10th	Night	31% 8% 13% 23% 18% 8%	5028
	11th to 20th	Night	21% 7% 16% 21% 19% 15%	5090
	21st to end	Night	31% 6% 10% 27% 22% 5%	5588
April	1st to 10th	Night	25% 7% 19% 27% 15% 7%	2310
	11th to 20th	Night	25% 7% 16% 21% 23% 7%	2283
	21st to end	Night	22% 7% 15% 26% 26% 3	2165
May	1st to 10th	Night	24% 10% 22% 29% 12% 3	5264
	11th to 20th	Night	29% 8% 18% 30% 13% 1	5235
	21st to end	Night	29% 11% 20% 27% 12%	5771
June	1st to 10th	Night	39% 10% 22% 22% 6%	1890
	11th to 20th	Night	34% 14% 29% 20% 3	1890
	21st to end	Night	35% 17% 28% 15% 5%	1890
July	1st to 10th	Night	43% 19% 32% 5%	5235
	11th to 20th	Night	42% 19% 31% 8%	5226
	21st to end	Night	44% 17% 26% 13% 1	5606
August	1st to 10th	Night	42% 18% 28% 8% 4	4261
	11th to 20th	Night	24% 14% 33% 27% 2	4590
	21st to end	Night	41% 20% 30% 8% 1	5533
September	1st to 10th	Night	41% 19% 27% 12% 1	2310
	11th to 20th	Night	45% 15% 22% 15% 3	2234
	21st to end	Night	41% 14% 19% 17% 8% 1	2200
October	1st to 10th	Night	53% 11% 14% 11% 8% 4	3590
	11th to 20th	Night	25% 8% 11% 27% 25% 4	3798
	21st to end	Night	29% 6% 9% 26% 24% 6%	4252
November	1st to 10th	Night	31% 6% 11% 21% 20% 11%	2461
	11th to 20th	Night	31% 6% 11% 23% 20% 9%	2520
	21st to end	Night	31% 7% 12% 22% 20% 8%	2663
December	1st to 10th	Night	21% 6% 16% 30% 15% 12%	4380
	11th to 20th	Night	33% 6% 11% 20% 21% 8%	4954
	21st to end	Night	42% 8% 15% 17% 14% 3	6633

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	9% 9% 38% 33% 11% 1	330
	11th to 20th	Day	11% 14% 33% 26% 13% 3	330
	21st to end	Day	12% 15% 42% 26% 5%	363
February	1st to 10th	Day	9% 10% 29% 34% 16% 2	330
	11th to 20th	Day	6% 8% 31% 38% 14% 3	330
	21st to end	Day	8% 6% 28% 40% 16% 2	331
March	1st to 10th	Day	5% 6% 37% 35% 15% 1	540
	11th to 20th	Day	7% 10% 29% 31% 21% 1	540
	21st to end	Day	5% 5% 31% 35% 20% 4	594
April	1st to 10th	Day	5% 6% 32% 37% 17% 2	540
	11th to 20th	Day	6% 8% 24% 39% 20% 4	532
	21st to end	Day	4 2 23% 37% 30% 4	540
May	1st to 10th	Day	5% 3 20% 35% 29% 8%	543
	11th to 20th	Day	9% 4 17% 30% 27% 13%	567
	21st to end	Day	6% 2 10% 25% 37% 21%	617
June	1st to 10th	Day	12% 4 10% 25% 31% 19%	570
	11th to 20th	Day	7% 3 6% 25% 30% 28%	570
	21st to end	Day	5% 1 4 15% 30% 44%	570
July	1st to 10th	Day	4 1 3 13% 32% 47%	565
	11th to 20th	Day	6% 1 4 11% 34% 44%	564
	21st to end	Day	8% 1 5% 16% 29% 40%	620
August	1st to 10th	Day	7% 1 5% 12% 34% 40%	566
	11th to 20th	Day	4 1 3 13% 31% 47%	559
	21st to end	Day	7% 1 6% 19% 31% 35%	627
September	1st to 10th	Day	8% 1 4 16% 33% 37%	570
	11th to 20th	Day	8% 2 7% 22% 34% 27%	542
	21st to end	Day	5% 2 7% 22% 37% 28%	530
October	1st to 10th	Day	11% 3 13% 32% 32% 9%	530
	11th to 20th	Day	5% 3 17% 33% 31% 12%	530
	21st to end	Day	8% 4 20% 33% 30% 6%	583
November	1st to 10th	Day	7% 4 20% 35% 28% 5%	535
	11th to 20th	Day	10% 4 21% 37% 23% 5%	540
	21st to end	Day	8% 6% 25% 34% 23% 5%	393
December	1st to 10th	Day	4 10% 33% 32% 15% 6%	330
	11th to 20th	Day	8% 8% 32% 30% 19% 3	330
	21st to end	Day	5% 7% 32% 33% 18% 4	363
January	1st to 10th	Night	11% 5% 26% 38% 18% 1	840
	11th to 20th	Night	12% 6% 25% 41% 15% 1	840
	21st to end	Night	12% 8% 30% 38% 12%	924
February	1st to 10th	Night	11% 6% 29% 38% 17% 1	840
	11th to 20th	Night	10% 4 25% 42% 17% 1	823
	21st to end	Night	7% 4 23% 45% 20%	692
March	1st to 10th	Night	5% 5% 31% 45% 14% 1	840
	11th to 20th	Night	6% 5% 25% 43% 20% 1	840
	21st to end	Night	6% 4 26% 44% 19% 2	924
April	1st to 10th	Night	5% 5% 23% 46% 20% 1	840
	11th to 20th	Night	6% 4 25% 45% 18% 1	831
	21st to end	Night	5% 2 23% 45% 23% 1	838
May	1st to 10th	Night	3 1 12% 46% 35% 3	630
	11th to 20th	Night	7% 2 11% 40% 35% 5%	621
	21st to end	Night	6% 1 8% 33% 45% 7%	683
June	1st to 10th	Night	10% 5% 25% 46% 13%	630
	11th to 20th	Night	5% 2 5% 14% 50% 24%	630
	21st to end	Night	6% 2 2 11% 47% 32%	630
July	1st to 10th	Night	7% 1 3 7% 44% 38%	615
	11th to 20th	Night	4 1 3 9% 40% 43%	612
	21st to end	Night	5% 1 3 8% 46% 37%	690
August	1st to 10th	Night	5% 1 3 11% 45% 36%	627
	11th to 20th	Night	6% 1 2 8% 39% 44%	624
	21st to end	Night	11% 2 6% 15% 41% 26%	910
September	1st to 10th	Night	7% 2 5% 17% 45% 24%	840
	11th to 20th	Night	9% 3 6% 22% 40% 20%	813
	21st to end	Night	10% 2 7% 26% 42% 14%	800
October	1st to 10th	Night	11% 2 13% 38% 31% 5%	800
	11th to 20th	Night	8% 3 14% 38% 35% 4	800
	21st to end	Night	9% 3 19% 39% 27% 3	880
November	1st to 10th	Night	7% 3 24% 43% 21% 3	820
	11th to 20th	Night	8% 4 20% 43% 23% 2	840
	21st to end	Night	8% 3 23% 43% 21% 1	840
December	1st to 10th	Night	8% 5% 21% 38% 26% 1	840
	11th to 20th	Night	9% 5% 23% 40% 21% 2	840
	21st to end	Night	9% 4 25% 39% 22% 1	924

Page generated at 2026-09-11 04:11:54. Version ac07

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