Gulfport
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Gulfport clear sky chart from 2005-11-06 to 2024-02-20.

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	11% 5% 2 5% 5% 3 5% 5% 7% 9% 42%	78968
	Night	11% 5% 2 5% 5% 3 4 5% 6% 8% 46%	80211
Transparency	Day	37% 7% 13% 19% 17% 7%	78714
	Night	35% 6% 13% 19% 18% 8%	79984
Seeing	Day	13% 4 18% 27% 24% 14%	13256
	Night	13% 5% 18% 29% 26% 9%	23281

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% 5% 2 5% 4 3 5% 4 6% 7% 44%	3156
	11th to 20th	Day	12% 5% 2 4 4 2 4 3 4 6% 54%	3160
	21st to end	Day	25% 7% 3 5% 4 2 3 4 4 6% 37%	3476
February	1st to 10th	Day	16% 8% 3 6% 5% 3 3 4 4 5% 42%	1900
	11th to 20th	Day	16% 6% 2 4 5% 2 4 5% 4 7% 43%	1838
	21st to end	Day	17% 8% 3 5% 6% 4 4 5% 6% 6% 35%	1480
March	1st to 10th	Day	13% 6% 2 6% 5% 3 4 4 5% 7% 45%	1800
	11th to 20th	Day	13% 7% 3 5% 5% 3 5% 4 5% 8% 42%	1949
	21st to end	Day	11% 5% 2 5% 5% 3 5% 4 5% 8% 47%	2344
April	1st to 10th	Day	9% 5% 3 4 5% 3 5% 6% 6% 9% 45%	2160
	11th to 20th	Day	13% 6% 3 4 6% 2 5% 5% 6% 8% 41%	2134
	21st to end	Day	8% 5% 2 4 4 3 5% 5% 5% 7% 51%	2160
May	1st to 10th	Day	9% 4 2 4 4 3 5% 5% 6% 8% 51%	2160
	11th to 20th	Day	8% 5% 2 4 6% 4 5% 6% 7% 9% 45%	2124
	21st to end	Day	6% 4 2 5% 6% 3 5% 6% 8% 12% 42%	2448
June	1st to 10th	Day	8% 4 3 6% 7% 4 7% 7% 9% 10% 35%	2340
	11th to 20th	Day	4 3 2 4 6% 4 7% 8% 9% 13% 41%	2340
	21st to end	Day	7% 6% 2 7% 6% 4 7% 9% 10% 14% 29%	2297
July	1st to 10th	Day	8% 5% 3 8% 7% 5% 9% 8% 9% 14% 25%	2160
	11th to 20th	Day	8% 6% 3 6% 8% 5% 8% 8% 9% 12% 28%	2160
	21st to end	Day	5% 5% 3 7% 7% 4 7% 8% 11% 12% 31%	2350
August	1st to 10th	Day	4 4 2 6% 7% 5% 7% 9% 10% 14% 33%	2148
	11th to 20th	Day	8% 6% 3 6% 6% 5% 8% 9% 10% 10% 28%	2125
	21st to end	Day	9% 5% 2 6% 6% 5% 6% 8% 9% 12% 32%	2376
September	1st to 10th	Day	8% 4 3 5% 6% 4 7% 7% 8% 10% 38%	2160
	11th to 20th	Day	9% 5% 2 5% 5% 4 5% 6% 8% 9% 41%	2044
	21st to end	Day	8% 4 2 4 5% 3 5% 6% 6% 9% 48%	1980
October	1st to 10th	Day	5% 3 1 3 4 3 5% 5% 6% 8% 57%	1980
	11th to 20th	Day	6% 3 2 4 4 3 5% 4 6% 7% 57%	1846
	21st to end	Day	10% 3 2 4 4 3 4 4 4 6% 57%	1980
November	1st to 10th	Day	9% 4 1 3 3 2 3 4 4 8% 59%	1825
	11th to 20th	Day	11% 3 2 4 4 2 3 3 5% 5% 58%	1710
	21st to end	Day	12% 6% 2 5% 5% 3 5% 4 5% 7% 47%	1710
December	1st to 10th	Day	14% 7% 3 6% 4 2 4 4 5% 7% 45%	1710
	11th to 20th	Day	14% 8% 3 6% 6% 3 5% 4 5% 7% 41%	2153
	21st to end	Day	16% 8% 3 6% 6% 3 4 4 5% 7% 38%	3285
January	1st to 10th	Night	15% 6% 2 4 5% 3 4 4 5% 7% 47%	3789
	11th to 20th	Night	14% 5% 3 4 3 2 3 3 4 7% 52%	3800
	21st to end	Night	24% 8% 2 3 3 2 3 4 4 6% 41%	4180
February	1st to 10th	Night	14% 7% 3 4 6% 3 4 4 5% 6% 43%	2280
	11th to 20th	Night	18% 7% 3 5% 4 3 4 3 5% 7% 42%	2213
	21st to end	Night	16% 9% 3 5% 5% 3 6% 4 5% 6% 37%	1776
March	1st to 10th	Night	12% 7% 2 5% 4 2 4 5% 6% 7% 44%	2160
	11th to 20th	Night	12% 7% 3 5% 5% 3 5% 5% 6% 9% 41%	2023
	21st to end	Night	11% 4 2 3 4 3 4 5% 5% 8% 51%	2012
April	1st to 10th	Night	11% 6% 3 6% 5% 3 4 4 6% 7% 46%	1800
	11th to 20th	Night	12% 6% 2 5% 5% 3 5% 5% 5% 7% 46%	1775
	21st to end	Night	6% 3 2 3 4 2 4 4 6% 8% 58%	1800
May	1st to 10th	Night	10% 3 2 3 4 2 3 5% 5% 9% 54%	1800
	11th to 20th	Night	4 4 2 5% 5% 3 7% 6% 7% 10% 46%	1769
	21st to end	Night	5% 3 2 4 4 3 5% 6% 8% 12% 46%	1819
June	1st to 10th	Night	7% 5% 3 5% 5% 4 7% 6% 8% 10% 41%	1620
	11th to 20th	Night	3 3 2 4 4 3 5% 8% 9% 14% 44%	1620
	21st to end	Night	6% 4 3 6% 6% 4 6% 6% 9% 13% 38%	1655
July	1st to 10th	Night	6% 6% 3 5% 6% 3 5% 7% 9% 12% 39%	1800
	11th to 20th	Night	3 3 3 6% 6% 5% 6% 7% 10% 13% 39%	1800
	21st to end	Night	5% 4 3 4 5% 4 6% 7% 9% 14% 39%	1968
August	1st to 10th	Night	2 4 2 4 4 3 4 6% 8% 15% 49%	1790
	11th to 20th	Night	4 3 3 6% 6% 4 7% 8% 11% 17% 32%	1776
	21st to end	Night	8% 4 3 5% 6% 4 6% 7% 8% 11% 38%	1980
September	1st to 10th	Night	6% 4 3 6% 7% 4 6% 8% 7% 10% 39%	1800
	11th to 20th	Night	8% 6% 2 5% 5% 3 4 6% 7% 10% 44%	1895
	21st to end	Night	7% 5% 2 4 5% 3 4 4 6% 9% 51%	1980
October	1st to 10th	Night	6% 3 2 5% 4 2 3 4 5% 7% 58%	1980
	11th to 20th	Night	6% 3 2 3 4 2 4 4 5% 7% 60%	2110
	21st to end	Night	10% 5% 2 4 4 3 3 4 5% 6% 55%	2376
November	1st to 10th	Night	9% 4 2 4 4 3 4 4 4 6% 56%	2248
	11th to 20th	Night	10% 5% 2 4 4 3 3 4 5% 6% 55%	2470
	21st to end	Night	9% 6% 2 6% 4 3 4 4 5% 7% 49%	2470
December	1st to 10th	Night	13% 7% 3 5% 5% 2 4 4 5% 7% 46%	2470
	11th to 20th	Night	14% 7% 2 5% 5% 3 4 5% 4 6% 44%	3042
	21st to end	Night	17% 8% 4 6% 6% 3 4 4 4 5% 38%	4365

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 7% 16% 23% 12%	3157
	11th to 20th	Day	31% 3 7% 18% 30% 11%	3160
	21st to end	Day	48% 3 4 16% 19% 9%	3476
February	1st to 10th	Day	45% 4 9% 13% 20% 10%	1900
	11th to 20th	Day	41% 4 8% 18% 19% 11%	1848
	21st to end	Day	47% 4 9% 15% 16% 9%	1480
March	1st to 10th	Day	38% 5% 8% 21% 20% 7%	1800
	11th to 20th	Day	41% 6% 10% 15% 20% 7%	1949
	21st to end	Day	36% 5% 13% 21% 19% 7%	2344
April	1st to 10th	Day	34% 6% 14% 19% 17% 9%	2160
	11th to 20th	Day	39% 5% 9% 20% 19% 8%	2134
	21st to end	Day	30% 5% 11% 23% 23% 7%	2160
May	1st to 10th	Day	31% 6% 11% 25% 20% 7%	2160
	11th to 20th	Day	35% 8% 16% 22% 18% 2	2128
	21st to end	Day	32% 9% 17% 25% 14% 3	2448
June	1st to 10th	Day	41% 8% 17% 24% 9% 1	2340
	11th to 20th	Day	32% 9% 20% 28% 10% 2	2340
	21st to end	Day	40% 11% 22% 17% 9%	2297
July	1st to 10th	Day	47% 12% 23% 16% 3	2100
	11th to 20th	Day	44% 12% 24% 16% 3 1	2097
	21st to end	Day	39% 12% 26% 19% 4	2219
August	1st to 10th	Day	37% 12% 26% 19% 5%	2136
	11th to 20th	Day	46% 11% 23% 15% 5% 1	2125
	21st to end	Day	41% 12% 20% 18% 7% 2	2376
September	1st to 10th	Day	37% 10% 19% 18% 11% 4	2160
	11th to 20th	Day	37% 10% 15% 17% 15% 6%	2044
	21st to end	Day	32% 7% 13% 23% 18% 8%	1980
October	1st to 10th	Day	25% 5% 13% 22% 21% 14%	1980
	11th to 20th	Day	27% 4 9% 21% 26% 13%	1846
	21st to end	Day	29% 4 6% 17% 27% 16%	1980
November	1st to 10th	Day	26% 4 9% 22% 26% 12%	1825
	11th to 20th	Day	30% 3 7% 19% 30% 12%	1710
	21st to end	Day	37% 4 8% 19% 20% 12%	1710
December	1st to 10th	Day	39% 4 10% 20% 19% 7%	1710
	11th to 20th	Day	44% 4 8% 14% 20% 10%	2150
	21st to end	Day	45% 4 8% 18% 21% 5%	3285
January	1st to 10th	Night	38% 4 7% 14% 26% 11%	3789
	11th to 20th	Night	35% 3 5% 18% 29% 10%	3800
	21st to end	Night	46% 3 5% 16% 22% 9%	4180
February	1st to 10th	Night	41% 4 7% 18% 20% 10%	2280
	11th to 20th	Night	43% 4 5% 16% 19% 13%	2214
	21st to end	Night	46% 6% 9% 15% 12% 12%	1776
March	1st to 10th	Night	38% 5% 9% 17% 22% 10%	2160
	11th to 20th	Night	40% 6% 13% 16% 18% 7%	2023
	21st to end	Night	32% 6% 13% 19% 22% 8%	2012
April	1st to 10th	Night	38% 5% 12% 17% 18% 11%	1800
	11th to 20th	Night	37% 4 9% 23% 19% 8%	1775
	21st to end	Night	25% 4 11% 26% 26% 9%	1800
May	1st to 10th	Night	29% 4 11% 27% 23% 6%	1800
	11th to 20th	Night	31% 10% 16% 23% 19% 3	1770
	21st to end	Night	28% 8% 18% 27% 16% 3	1820
June	1st to 10th	Night	36% 8% 20% 26% 10% 1	1620
	11th to 20th	Night	25% 10% 26% 26% 11% 1	1620
	21st to end	Night	36% 10% 25% 19% 9% 1	1655
July	1st to 10th	Night	36% 10% 28% 21% 4	1750
	11th to 20th	Night	31% 13% 34% 19% 3 1	1740
	21st to end	Night	29% 14% 29% 24% 4	1858
August	1st to 10th	Night	23% 12% 36% 23% 6%	1778
	11th to 20th	Night	33% 15% 29% 17% 5%	1776
	21st to end	Night	37% 11% 25% 17% 6% 3	1980
September	1st to 10th	Night	36% 10% 19% 17% 14% 5%	1800
	11th to 20th	Night	33% 9% 19% 17% 14% 7%	1895
	21st to end	Night	30% 5% 15% 24% 17% 9%	1980
October	1st to 10th	Night	25% 5% 12% 20% 22% 16%	1980
	11th to 20th	Night	23% 4 10% 23% 25% 14%	2110
	21st to end	Night	30% 4 6% 16% 27% 17%	2376
November	1st to 10th	Night	30% 3 6% 20% 26% 15%	2248
	11th to 20th	Night	31% 4 6% 17% 29% 13%	2470
	21st to end	Night	35% 4 7% 21% 20% 12%	2470
December	1st to 10th	Night	39% 4 10% 19% 21% 6%	2470
	11th to 20th	Night	41% 4 7% 15% 20% 13%	3044
	21st to end	Night	47% 4 7% 18% 18% 6%	4365

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	20% 11% 36% 24% 8% 1	270
	11th to 20th	Day	19% 11% 31% 28% 10% 2	270
	21st to end	Day	20% 12% 38% 24% 5%	297
February	1st to 10th	Day	25% 11% 33% 22% 7% 1	270
	11th to 20th	Day	28% 9% 34% 19% 9% 1	267
	21st to end	Day	20% 9% 45% 22% 4	198
March	1st to 10th	Day	15% 13% 35% 30% 8%	240
	11th to 20th	Day	17% 11% 41% 22% 8% 1	240
	21st to end	Day	18% 7% 31% 30% 12% 2	430
April	1st to 10th	Day	14% 6% 36% 28% 14% 1	420
	11th to 20th	Day	20% 10% 28% 25% 14% 3	412
	21st to end	Day	10% 4 29% 32% 21% 4	420
May	1st to 10th	Day	13% 4 26% 33% 19% 5%	423
	11th to 20th	Day	11% 2 16% 35% 25% 12%	447
	21st to end	Day	8% 2 11% 34% 32% 13%	485
June	1st to 10th	Day	12% 1 8% 31% 29% 19%	450
	11th to 20th	Day	8% 3 9% 28% 33% 19%	450
	21st to end	Day	10% 2 6% 27% 30% 24%	450
July	1st to 10th	Day	11% 1 2 20% 33% 33%	445
	11th to 20th	Day	10% 2 3 16% 34% 34%	444
	21st to end	Day	6% 2 3 24% 38% 27%	488
August	1st to 10th	Day	6% 2 2 18% 38% 34%	446
	11th to 20th	Day	9% 2 1 18% 35% 35%	439
	21st to end	Day	10% 1 7% 20% 35% 28%	495
September	1st to 10th	Day	8% 2 3 22% 39% 27%	450
	11th to 20th	Day	12% 3 6% 23% 38% 18%	450
	21st to end	Day	10% 2 8% 30% 33% 18%	450
October	1st to 10th	Day	7% 2 15% 36% 29% 11%	450
	11th to 20th	Day	6% 1 19% 36% 25% 13%	316
	21st to end	Day	17% 6% 18% 30% 23% 7%	297
November	1st to 10th	Day	13% 2 21% 35% 23% 5%	270
	11th to 20th	Day	18% 4 29% 29% 15% 5%	270
	21st to end	Day	17% 5% 30% 29% 15% 4	270
December	1st to 10th	Day	18% 4 29% 33% 12% 4	270
	11th to 20th	Day	22% 10% 31% 26% 10% 1	270
	21st to end	Day	27% 7% 28% 24% 13% 2	297
January	1st to 10th	Night	19% 9% 31% 34% 7%	760
	11th to 20th	Night	16% 7% 31% 36% 10%	760
	21st to end	Night	23% 8% 33% 30% 6%	836
February	1st to 10th	Night	19% 8% 33% 32% 8%	760
	11th to 20th	Night	23% 10% 29% 29% 9%	742
	21st to end	Night	21% 10% 33% 29% 6%	592
March	1st to 10th	Night	17% 9% 30% 33% 10%	720
	11th to 20th	Night	16% 5% 29% 32% 17% 1	583
	21st to end	Night	15% 5% 27% 35% 17% 1	594
April	1st to 10th	Night	15% 6% 27% 33% 17% 1	540
	11th to 20th	Night	15% 5% 29% 28% 20% 2	533
	21st to end	Night	9% 3 22% 40% 24% 2	540
May	1st to 10th	Night	11% 2 17% 40% 28% 3	540
	11th to 20th	Night	6% 2 14% 38% 34% 7%	531
	21st to end	Night	5% 2 8% 31% 44% 10%	584
June	1st to 10th	Night	10% 1 6% 25% 44% 14%	540
	11th to 20th	Night	4 2 4 26% 47% 18%	540
	21st to end	Night	7% 1 4 22% 42% 23%	540
July	1st to 10th	Night	7% 1 2 14% 50% 27%	525
	11th to 20th	Night	3 1 2 8% 46% 40%	522
	21st to end	Night	4 3 2 16% 46% 29%	591
August	1st to 10th	Night	3 1 1 11% 48% 37%	537
	11th to 20th	Night	5% 1 1 10% 50% 34%	534
	21st to end	Night	8% 2 4 15% 45% 26%	594
September	1st to 10th	Night	9% 1 4 16% 46% 25%	540
	11th to 20th	Night	10% 2 6% 23% 46% 13%	635
	21st to end	Night	9% 2 6% 32% 43% 9%	720
October	1st to 10th	Night	7% 2 13% 37% 36% 5%	720
	11th to 20th	Night	9% 4 14% 35% 31% 8%	720
	21st to end	Night	13% 4 18% 37% 26% 3	792
November	1st to 10th	Night	12% 4 15% 40% 26% 4	740
	11th to 20th	Night	14% 4 26% 37% 18% 2	760
	21st to end	Night	13% 6% 25% 36% 18% 2	760
December	1st to 10th	Night	18% 6% 28% 30% 18% 1	760
	11th to 20th	Night	18% 6% 26% 35% 13% 1	760
	21st to end	Night	26% 7% 28% 28% 11%	836

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