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 2025-03-27.

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% 5% 5% 5% 5% 7% 9% 42%	109207
	Night	11% 6% 2 6% 4 4 4 4 6% 8% 45%	110151
Transparency	Day	21% 45% 8% 11% 11% 5%	113030
	Night	22% 43% 8% 11% 11% 5%	114466
Seeing	Day	13% 5% 19% 27% 23% 13%	14668
	Night	13% 5% 19% 30% 26% 8%	24684

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	16% 4 2 5% 3 4 4 3 6% 6% 48%	4516
	11th to 20th	Day	14% 6% 2 5% 4 3 3 3 4 5% 50%	4520
	21st to end	Day	21% 7% 3 6% 4 3 4 4 5% 6% 36%	4972
February	1st to 10th	Day	15% 9% 3 7% 5% 4 3 3 5% 5% 41%	2000
	11th to 20th	Day	16% 7% 2 5% 4 3 4 4 5% 7% 43%	1948
	21st to end	Day	16% 9% 2 6% 5% 5% 3 4 7% 6% 36%	1650
March	1st to 10th	Day	21% 9% 3 8% 4 4 4 4 5% 7% 32%	3220
	11th to 20th	Day	14% 7% 3 6% 5% 4 5% 3 6% 9% 39%	3544
	21st to end	Day	11% 6% 2 6% 4 5% 5% 4 6% 7% 44%	4189
April	1st to 10th	Day	10% 5% 2 5% 5% 5% 5% 5% 6% 9% 44%	2280
	11th to 20th	Day	12% 7% 3 5% 5% 3 5% 4 6% 9% 41%	2254
	21st to end	Day	7% 6% 2 4 4 5% 5% 4 5% 8% 51%	2280
May	1st to 10th	Day	9% 5% 2 6% 5% 5% 6% 5% 9% 10% 38%	3765
	11th to 20th	Day	12% 6% 2 6% 5% 4 4 4 6% 8% 43%	3764
	21st to end	Day	5% 4 1 5% 4 4 4 5% 9% 12% 48%	4337
June	1st to 10th	Day	8% 5% 3 7% 6% 5% 7% 6% 8% 10% 35%	2470
	11th to 20th	Day	4 4 2 5% 5% 6% 6% 6% 9% 12% 41%	2470
	21st to end	Day	7% 6% 2 7% 5% 6% 6% 8% 10% 14% 29%	2424
July	1st to 10th	Day	6% 5% 2 8% 6% 7% 8% 7% 11% 15% 25%	3800
	11th to 20th	Day	5% 4 2 6% 6% 6% 6% 6% 8% 12% 38%	3800
	21st to end	Day	4 4 2 8% 7% 7% 8% 7% 12% 15% 25%	4118
August	1st to 10th	Day	3 2 1 4 4 4 5% 6% 9% 13% 49%	3785
	11th to 20th	Day	5% 4 2 5% 4 5% 6% 6% 9% 13% 41%	3729
	21st to end	Day	6% 6% 3 9% 6% 6% 7% 6% 7% 9% 34%	4180
September	1st to 10th	Day	10% 5% 2 7% 4 5% 8% 5% 8% 9% 36%	2280
	11th to 20th	Day	9% 6% 2 5% 5% 6% 5% 5% 8% 10% 41%	2157
	21st to end	Day	7% 3 2 4 4 5% 5% 5% 7% 9% 49%	2090
October	1st to 10th	Day	5% 3 1 4 3 4 5% 4 6% 7% 57%	2090
	11th to 20th	Day	5% 3 2 5% 3 5% 4 2 6% 7% 58%	1948
	21st to end	Day	9% 4 2 4 3 4 4 3 4 6% 58%	2090
November	1st to 10th	Day	9% 4 1 4 3 3 4 4 5% 7% 57%	1923
	11th to 20th	Day	12% 4 2 4 4 3 2 3 4 5% 58%	1800
	21st to end	Day	11% 7% 2 5% 5% 4 4 3 5% 7% 48%	1800
December	1st to 10th	Day	16% 6% 2 6% 4 4 4 3 5% 6% 43%	2930
	11th to 20th	Day	9% 7% 2 6% 4 4 5% 4 6% 8% 47%	3373
	21st to end	Day	17% 8% 2 7% 4 4 3 3 4 6% 42%	4711
January	1st to 10th	Night	15% 6% 2 5% 3 3 3 3 5% 6% 47%	5429
	11th to 20th	Night	18% 8% 3 6% 3 2 2 2 4 6% 46%	5440
	21st to end	Night	21% 7% 2 5% 4 4 4 3 5% 7% 38%	5984
February	1st to 10th	Night	13% 8% 3 6% 5% 4 4 4 5% 6% 43%	2400
	11th to 20th	Night	19% 7% 3 6% 4 4 3 3 5% 6% 41%	2338
	21st to end	Night	15% 9% 3 6% 4 5% 4 4 5% 6% 39%	1980
March	1st to 10th	Night	21% 11% 3 7% 4 3 4 3 5% 6% 32%	3853
	11th to 20th	Night	11% 7% 2 6% 5% 5% 5% 4 6% 8% 40%	3663
	21st to end	Night	13% 5% 2 5% 3 4 5% 4 5% 7% 46%	3579
April	1st to 10th	Night	11% 7% 3 7% 4 4 4 4 6% 6% 46%	1900
	11th to 20th	Night	11% 6% 2 6% 4 4 5% 4 6% 7% 45%	1875
	21st to end	Night	6% 4 2 4 3 3 3 4 6% 7% 57%	1900
May	1st to 10th	Night	12% 5% 2 6% 4 4 5% 4 5% 8% 45%	3130
	11th to 20th	Night	12% 5% 2 7% 5% 4 6% 3 6% 7% 42%	3129
	21st to end	Night	4 3 2 5% 3 4 4 5% 8% 14% 47%	3210
June	1st to 10th	Night	7% 5% 2 6% 5% 5% 7% 5% 8% 10% 40%	1710
	11th to 20th	Night	3 4 2 5% 4 4 6% 6% 9% 13% 44%	1710
	21st to end	Night	6% 5% 2 7% 5% 5% 5% 6% 9% 12% 38%	1748
July	1st to 10th	Night	4 5% 2 6% 5% 6% 7% 6% 10% 16% 35%	3160
	11th to 20th	Night	1 3 2 6% 5% 6% 5% 5% 8% 13% 47%	3160
	21st to end	Night	4 5% 2 6% 6% 7% 7% 7% 12% 16% 29%	3435
August	1st to 10th	Night	2 3 1 3 3 3 4 4 7% 14% 56%	3144
	11th to 20th	Night	3 2 2 5% 4 4 6% 6% 9% 15% 43%	3100
	21st to end	Night	5% 4 2 7% 6% 7% 7% 6% 8% 10% 39%	3476
September	1st to 10th	Night	8% 5% 3 8% 6% 5% 6% 6% 7% 9% 37%	1900
	11th to 20th	Night	9% 6% 2 5% 4 4 5% 5% 7% 10% 43%	2001
	21st to end	Night	7% 5% 2 5% 4 4 4 3 6% 9% 52%	2090
October	1st to 10th	Night	6% 4 2 6% 3 3 4 3 5% 6% 57%	2090
	11th to 20th	Night	6% 4 1 4 3 3 3 3 5% 7% 61%	2228
	21st to end	Night	9% 5% 2 5% 3 4 3 3 5% 6% 56%	2508
November	1st to 10th	Night	9% 5% 2 5% 4 4 4 3 5% 6% 55%	2370
	11th to 20th	Night	11% 5% 2 5% 4 3 3 3 5% 5% 54%	2600
	21st to end	Night	9% 6% 2 6% 3 5% 4 3 5% 7% 49%	2600
December	1st to 10th	Night	12% 6% 3 6% 4 5% 4 4 5% 6% 44%	4250
	11th to 20th	Night	11% 6% 2 5% 4 3 4 4 5% 6% 51%	4822
	21st to end	Night	17% 8% 3 7% 4 4 3 3 4 4 42%	6239

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% 27% 5% 15% 20% 7%	4517
	11th to 20th	Day	27% 26% 4 12% 23% 8%	4520
	21st to end	Day	35% 30% 6% 10% 11% 8%	4972
February	1st to 10th	Day	20% 61% 3 4 7% 4	2000
	11th to 20th	Day	16% 62% 3 9% 8% 2	1958
	21st to end	Day	17% 63% 4 5% 8% 4	1650
March	1st to 10th	Day	38% 40% 6% 10% 5% 2	3220
	11th to 20th	Day	27% 41% 6% 13% 11% 2	3544
	21st to end	Day	24% 42% 8% 10% 10% 7%	4189
April	1st to 10th	Day	14% 66% 3 6% 8% 3	2280
	11th to 20th	Day	15% 66% 4 6% 6% 3	2254
	21st to end	Day	12% 65% 3 8% 7% 4	2280
May	1st to 10th	Day	22% 44% 12% 13% 7% 3	3800
	11th to 20th	Day	25% 41% 7% 13% 13% 1	3768
	21st to end	Day	15% 42% 14% 23% 5% 1	4350
June	1st to 10th	Day	14% 67% 7% 8% 4	2470
	11th to 20th	Day	14% 69% 7% 7% 4	2470
	21st to end	Day	15% 66% 8% 6% 3	2424
July	1st to 10th	Day	26% 44% 19% 11% 1	3740
	11th to 20th	Day	21% 45% 29% 4	3737
	21st to end	Day	27% 47% 15% 10% 2	3987
August	1st to 10th	Day	10% 39% 10% 21% 18% 1	3773
	11th to 20th	Day	13% 42% 15% 21% 8% 1	3765
	21st to end	Day	27% 43% 9% 11% 9% 1	4179
September	1st to 10th	Day	16% 63% 8% 6% 4 2	2280
	11th to 20th	Day	10% 62% 10% 9% 8% 2	2157
	21st to end	Day	11% 62% 6% 13% 6% 2	2090
October	1st to 10th	Day	16% 37% 6% 7% 11% 22%	3480
	11th to 20th	Day	5% 37% 2 13% 19% 24%	3214
	21st to end	Day	10% 37% 3 6% 30% 14%	3428
November	1st to 10th	Day	16% 56% 5% 12% 7% 4	1923
	11th to 20th	Day	17% 57% 3 8% 11% 5%	1800
	21st to end	Day	17% 57% 4 9% 8% 6%	1800
December	1st to 10th	Day	30% 36% 5% 8% 17% 4	2930
	11th to 20th	Day	20% 33% 7% 14% 17% 9%	3370
	21st to end	Day	33% 27% 5% 11% 19% 5%	4711
January	1st to 10th	Night	29% 26% 4 13% 20% 7%	5429
	11th to 20th	Night	32% 26% 3 11% 22% 5%	5440
	21st to end	Night	35% 29% 5% 11% 13% 7%	5984
February	1st to 10th	Night	17% 62% 3 6% 8% 3	2400
	11th to 20th	Night	18% 61% 2 8% 8% 3	2339
	21st to end	Night	18% 62% 4 5% 7% 4	1980
March	1st to 10th	Night	41% 41% 5% 7% 4 2	3853
	11th to 20th	Night	27% 41% 6% 10% 10% 5%	3663
	21st to end	Night	24% 41% 6% 13% 10% 6%	3579
April	1st to 10th	Night	14% 65% 4 4 8% 5%	1900
	11th to 20th	Night	15% 67% 3 7% 6% 3	1875
	21st to end	Night	11% 65% 3 8% 9% 3	1900
May	1st to 10th	Night	23% 43% 10% 12% 10% 3	3160
	11th to 20th	Night	27% 42% 6% 15% 9% 1	3130
	21st to end	Night	14% 42% 17% 19% 7% 1	3218
June	1st to 10th	Night	13% 66% 6% 10% 4 1	1710
	11th to 20th	Night	12% 67% 7% 9% 4	1710
	21st to end	Night	13% 67% 10% 5% 4	1748
July	1st to 10th	Night	19% 42% 26% 11% 2	3110
	11th to 20th	Night	16% 42% 36% 5% 1	3100
	21st to end	Night	25% 49% 13% 12% 2	3325
August	1st to 10th	Night	8% 39% 12% 22% 17% 1	3132
	11th to 20th	Night	13% 41% 18% 22% 6%	3130
	21st to end	Night	23% 43% 12% 14% 7% 2	3476
September	1st to 10th	Night	16% 62% 8% 7% 5% 2	1900
	11th to 20th	Night	11% 61% 9% 8% 7% 3	2001
	21st to end	Night	12% 60% 8% 13% 5% 2	2090
October	1st to 10th	Night	20% 38% 7% 7% 13% 15%	3480
	11th to 20th	Night	6% 37% 3 13% 18% 23%	3701
	21st to end	Night	10% 36% 3 4 30% 16%	4120
November	1st to 10th	Night	19% 56% 5% 9% 8% 4	2370
	11th to 20th	Night	18% 56% 3 6% 11% 5%	2600
	21st to end	Night	15% 57% 3 10% 10% 5%	2600
December	1st to 10th	Night	29% 36% 5% 9% 14% 7%	4250
	11th to 20th	Night	21% 33% 5% 17% 15% 9%	4824
	21st to end	Night	35% 27% 4 11% 18% 5%	6239

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	21% 11% 38% 22% 7% 1	300
	11th to 20th	Day	18% 12% 33% 26% 9% 2	300
	21st to end	Day	20% 12% 38% 25% 5%	330
February	1st to 10th	Day	24% 11% 33% 23% 8% 1	300
	11th to 20th	Day	27% 12% 34% 18% 8% 1	300
	21st to end	Day	18% 9% 49% 18% 5%	249
March	1st to 10th	Day	18% 14% 34% 28% 7%	300
	11th to 20th	Day	18% 14% 39% 20% 8% 1	300
	21st to end	Day	18% 7% 34% 28% 11% 2	495
April	1st to 10th	Day	16% 7% 36% 27% 13% 1	460
	11th to 20th	Day	19% 11% 29% 25% 13% 3	452
	21st to end	Day	10% 5% 29% 32% 20% 4	460
May	1st to 10th	Day	12% 4 27% 33% 18% 5%	463
	11th to 20th	Day	11% 3 16% 34% 24% 11%	487
	21st to end	Day	8% 2 14% 35% 29% 12%	529
June	1st to 10th	Day	11% 1 9% 31% 29% 18%	490
	11th to 20th	Day	8% 2 11% 29% 31% 18%	490
	21st to end	Day	10% 2 7% 28% 30% 24%	490
July	1st to 10th	Day	10% 1 3 22% 33% 32%	485
	11th to 20th	Day	9% 3 3 16% 35% 34%	484
	21st to end	Day	6% 2 3 24% 39% 26%	532
August	1st to 10th	Day	6% 1 2 20% 39% 32%	486
	11th to 20th	Day	8% 2 2 20% 34% 34%	479
	21st to end	Day	9% 2 8% 21% 35% 26%	539
September	1st to 10th	Day	11% 3 3 21% 37% 25%	490
	11th to 20th	Day	12% 3 8% 23% 37% 17%	490
	21st to end	Day	9% 3 8% 30% 32% 17%	490
October	1st to 10th	Day	7% 3 16% 36% 28% 10%	490
	11th to 20th	Day	6% 1 22% 36% 23% 12%	348
	21st to end	Day	15% 5% 20% 32% 22% 6%	330
November	1st to 10th	Day	14% 3 22% 35% 21% 4	300
	11th to 20th	Day	18% 5% 28% 29% 14% 5%	300
	21st to end	Day	17% 6% 32% 28% 14% 4	300
December	1st to 10th	Day	19% 4 31% 31% 11% 3	300
	11th to 20th	Day	20% 10% 32% 26% 10% 1	300
	21st to end	Day	26% 7% 29% 24% 12% 2	330
January	1st to 10th	Night	18% 10% 32% 33% 7%	800
	11th to 20th	Night	17% 8% 31% 35% 9%	800
	21st to end	Night	23% 8% 32% 31% 5%	880
February	1st to 10th	Night	19% 9% 33% 32% 8%	800
	11th to 20th	Night	23% 11% 29% 27% 9%	783
	21st to end	Night	20% 10% 34% 29% 6%	660
March	1st to 10th	Night	18% 9% 31% 33% 10%	800
	11th to 20th	Night	15% 6% 30% 32% 15% 1	647
	21st to end	Night	14% 5% 27% 36% 17% 1	647
April	1st to 10th	Night	15% 7% 27% 33% 16% 1	570
	11th to 20th	Night	15% 5% 29% 29% 20% 2	563
	21st to end	Night	9% 3 22% 39% 24% 2	570
May	1st to 10th	Night	11% 2 18% 39% 27% 3	570
	11th to 20th	Night	7% 1 15% 38% 32% 7%	561
	21st to end	Night	6% 2 8% 33% 42% 10%	617
June	1st to 10th	Night	10% 1 6% 25% 45% 13%	570
	11th to 20th	Night	4 2 5% 26% 46% 17%	570
	21st to end	Night	7% 1 4 23% 42% 22%	570
July	1st to 10th	Night	7% 1 2 14% 49% 26%	555
	11th to 20th	Night	3 1 1 8% 46% 40%	552
	21st to end	Night	5% 3 2 16% 47% 28%	624
August	1st to 10th	Night	3 1 1 11% 49% 35%	567
	11th to 20th	Night	5% 1 1 10% 49% 33%	564
	21st to end	Night	8% 2 4 16% 45% 25%	627
September	1st to 10th	Night	10% 1 4 15% 45% 24%	570
	11th to 20th	Night	10% 2 7% 24% 45% 12%	671
	21st to end	Night	9% 2 7% 32% 42% 9%	760
October	1st to 10th	Night	8% 2 14% 37% 35% 5%	760
	11th to 20th	Night	9% 4 14% 36% 30% 7%	760
	21st to end	Night	12% 3 18% 38% 26% 3	836
November	1st to 10th	Night	12% 5% 16% 39% 24% 3	780
	11th to 20th	Night	15% 4 25% 36% 17% 2	800
	21st to end	Night	13% 7% 25% 36% 18% 2	800
December	1st to 10th	Night	17% 6% 28% 31% 17% 1	800
	11th to 20th	Night	18% 6% 26% 36% 13% 1	800
	21st to end	Night	26% 7% 28% 29% 10%	880

Page generated at 2025-03-24 08:04:25. Version ac07

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