Providence
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Providence clear sky chart from 2005-11-06 to 2026-08-30.

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	17% 7% 2 6% 4 4 4 4 5% 7% 39%	143546
	Night	17% 8% 3 6% 4 4 4 3 5% 6% 41%	138700
Transparency	Day	30% 35% 8% 15% 11% 2	147094
	Night	30% 35% 7% 15% 12% 2	143241
Seeing	Day	24% 18% 32% 17% 6% 2	17440
	Night	23% 15% 33% 23% 6%	26279

By Month

Percentage Cloud Cover NE (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	10% 8% 3 8% 4 4 4 3 5% 6% 45%	4661
	11th to 20th	Day	16% 8% 3 6% 3 3 4 3 4 4 47%	4650
	21st to end	Day	15% 9% 2 5% 4 3 3 3 4 6% 47%	5124
February	1st to 10th	Day	18% 7% 2 5% 4 5% 5% 4 6% 6% 38%	2001
	11th to 20th	Day	14% 7% 2 5% 4 4 5% 4 5% 6% 43%	2048
	21st to end	Day	19% 9% 3 5% 3 4 4 4 5% 6% 39%	1730
March	1st to 10th	Day	22% 11% 3 6% 3 3 3 2 4 6% 38%	4576
	11th to 20th	Day	16% 9% 2 5% 4 4 4 4 5% 7% 42%	4873
	21st to end	Day	24% 9% 2 6% 4 4 4 4 5% 5% 32%	5908
April	1st to 10th	Day	20% 8% 3 6% 4 3 3 3 5% 6% 38%	2520
	11th to 20th	Day	18% 7% 2 5% 3 3 4 3 6% 7% 40%	2494
	21st to end	Day	21% 6% 2 7% 4 4 4 4 4 5% 40%	2729
May	1st to 10th	Day	27% 9% 3 6% 3 4 4 3 5% 7% 29%	7639
	11th to 20th	Day	21% 8% 3 7% 4 4 4 3 4 6% 36%	7679
	21st to end	Day	22% 7% 2 6% 4 5% 5% 4 6% 8% 31%	9060
June	1st to 10th	Day	18% 6% 2 6% 4 4 5% 4 7% 9% 35%	2940
	11th to 20th	Day	15% 6% 2 6% 5% 4 5% 4 6% 9% 37%	2940
	21st to end	Day	15% 6% 2 5% 4 4 5% 4 7% 9% 37%	2940
July	1st to 10th	Day	18% 6% 2 6% 4 5% 5% 4 7% 9% 34%	8280
	11th to 20th	Day	10% 6% 2 6% 4 5% 5% 5% 7% 11% 40%	8280
	21st to end	Day	16% 7% 2 6% 4 4 4 3 5% 7% 41%	8993
August	1st to 10th	Day	17% 7% 3 8% 5% 5% 5% 4 6% 8% 31%	4378
	11th to 20th	Day	12% 6% 2 8% 5% 5% 6% 4 6% 8% 38%	4207
	21st to end	Day	8% 4 2 6% 5% 5% 6% 5% 7% 9% 45%	4420
September	1st to 10th	Day	15% 7% 2 6% 4 4 4 4 6% 6% 45%	2395
	11th to 20th	Day	13% 6% 2 5% 3 3 3 3 4 6% 51%	2200
	21st to end	Day	19% 7% 2 5% 4 4 5% 3 4 6% 42%	2200
October	1st to 10th	Day	22% 6% 1 5% 3 3 3 3 4 5% 44%	2200
	11th to 20th	Day	16% 5% 2 5% 3 3 3 3 5% 6% 48%	1970
	21st to end	Day	18% 5% 2 6% 4 4 3 4 4 5% 45%	1980
November	1st to 10th	Day	16% 6% 2 5% 4 4 4 3 4 5% 48%	1851
	11th to 20th	Day	17% 6% 1 4 3 3 3 3 4 7% 47%	1890
	21st to end	Day	18% 7% 1 5% 4 3 4 3 4 5% 45%	1890
December	1st to 10th	Day	15% 8% 2 5% 3 3 3 3 4 6% 48%	2786
	11th to 20th	Day	19% 6% 2 5% 3 2 3 3 3 5% 50%	3066
	21st to end	Day	20% 10% 3 7% 4 3 3 2 4 5% 39%	4048
January	1st to 10th	Night	15% 7% 2 5% 3 3 4 3 4 6% 49%	8234
	11th to 20th	Night	16% 11% 3 7% 4 4 4 3 4 5% 41%	8235
	21st to end	Night	14% 9% 3 7% 4 4 4 3 5% 5% 41%	9057
February	1st to 10th	Night	17% 8% 3 6% 5% 4 4 3 5% 6% 41%	2611
	11th to 20th	Night	17% 8% 3 6% 5% 3 3 4 5% 5% 41%	2458
	21st to end	Night	17% 9% 3 7% 4 3 4 3 4 4 41%	2076
March	1st to 10th	Night	24% 9% 2 4 3 3 3 3 5% 5% 39%	5484
	11th to 20th	Night	17% 10% 3 6% 4 3 4 3 5% 6% 40%	5306
	21st to end	Night	25% 9% 2 5% 4 4 4 4 5% 4 34%	5264
April	1st to 10th	Night	19% 9% 2 6% 5% 3 5% 3 5% 6% 37%	2100
	11th to 20th	Night	19% 8% 2 7% 4 4 4 4 5% 6% 38%	2075
	21st to end	Night	20% 8% 3 7% 4 3 3 3 4 6% 41%	1890
May	1st to 10th	Night	27% 9% 2 6% 4 4 4 3 4 6% 31%	5259
	11th to 20th	Night	19% 8% 3 7% 5% 5% 4 3 6% 7% 33%	5235
	21st to end	Night	22% 8% 3 7% 5% 5% 4 4 6% 7% 29%	5115
June	1st to 10th	Night	15% 7% 3 8% 4 4 4 4 6% 7% 38%	1680
	11th to 20th	Night	18% 6% 2 6% 5% 4 4 3 5% 9% 38%	1680
	21st to end	Night	16% 7% 2 5% 4 4 4 5% 6% 8% 39%	1680
July	1st to 10th	Night	18% 8% 3 6% 4 4 5% 4 6% 9% 33%	4680
	11th to 20th	Night	13% 8% 3 5% 4 3 5% 4 6% 8% 41%	4680
	21st to end	Night	15% 7% 2 6% 4 4 4 3 6% 7% 42%	5084
August	1st to 10th	Night	20% 7% 3 7% 5% 4 5% 4 7% 8% 30%	2956
	11th to 20th	Night	9% 7% 3 7% 5% 7% 6% 6% 6% 9% 36%	3056
	21st to end	Night	8% 5% 2 4 4 3 3 4 5% 8% 54%	3677
September	1st to 10th	Night	13% 5% 3 6% 5% 4 5% 4 5% 6% 43%	2005
	11th to 20th	Night	15% 5% 1 5% 3 3 3 3 4 6% 52%	2200
	21st to end	Night	19% 9% 2 6% 4 4 4 3 3 6% 41%	2200
October	1st to 10th	Night	19% 7% 3 5% 4 3 4 3 3 7% 43%	2200
	11th to 20th	Night	16% 5% 2 4 4 3 4 3 5% 7% 48%	2426
	21st to end	Night	20% 7% 2 6% 4 3 4 3 4 6% 41%	2860
November	1st to 10th	Night	14% 5% 2 5% 4 4 3 4 5% 5% 48%	2667
	11th to 20th	Night	17% 7% 2 5% 3 3 3 3 4 5% 47%	2730
	21st to end	Night	16% 6% 2 4 3 3 4 4 5% 7% 46%	2730
December	1st to 10th	Night	17% 8% 2 5% 3 3 3 2 4 5% 47%	4612
	11th to 20th	Night	22% 8% 2 5% 3 3 3 3 4 5% 42%	5348
	21st to end	Night	17% 10% 3 7% 4 3 3 2 4 5% 41%	7150

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	32% 22% 7% 20% 17% 3	4662
	11th to 20th	Day	32% 22% 6% 17% 16% 7%	4680
	21st to end	Day	33% 23% 8% 18% 18% 1	5124
February	1st to 10th	Day	19% 59% 7% 8% 6% 1	2001
	11th to 20th	Day	20% 58% 2 9% 9% 2	2057
	21st to end	Day	17% 59% 5% 11% 7% 1	1730
March	1st to 10th	Day	38% 29% 7% 8% 9% 10%	4579
	11th to 20th	Day	29% 30% 10% 21% 8% 1	4873
	21st to end	Day	42% 29% 4 11% 9% 5%	5908
April	1st to 10th	Day	22% 59% 3 7% 7% 2	2520
	11th to 20th	Day	18% 60% 4 8% 9% 1	2494
	21st to end	Day	20% 59% 3 9% 8% 2	2729
May	1st to 10th	Day	44% 26% 10% 12% 7% 1	7651
	11th to 20th	Day	41% 24% 11% 15% 8% 1	7683
	21st to end	Day	43% 25% 7% 15% 9%	9061
June	1st to 10th	Day	18% 59% 4 10% 8%	2940
	11th to 20th	Day	17% 60% 5% 11% 6% 1	2940
	21st to end	Day	16% 59% 5% 11% 9% 1	2940
July	1st to 10th	Day	37% 24% 11% 17% 9% 1	8210
	11th to 20th	Day	28% 24% 14% 23% 11%	8205
	21st to end	Day	34% 22% 8% 20% 16% 1	8795
August	1st to 10th	Day	34% 38% 10% 13% 5% 1	4364
	11th to 20th	Day	27% 38% 9% 20% 5%	4246
	21st to end	Day	17% 39% 10% 20% 12% 1	4420
September	1st to 10th	Day	17% 58% 4 12% 9%	2395
	11th to 20th	Day	17% 57% 4 10% 11% 2	2200
	21st to end	Day	21% 57% 4 9% 8% 1	2200
October	1st to 10th	Day	23% 37% 6% 15% 15% 3	3590
	11th to 20th	Day	17% 36% 4 17% 23% 3	3186
	21st to end	Day	17% 36% 9% 20% 16% 2	3180
November	1st to 10th	Day	19% 54% 6% 10% 10% 1	1851
	11th to 20th	Day	17% 54% 4 9% 13% 3	1890
	21st to end	Day	18% 54% 4 15% 7% 2	1890
December	1st to 10th	Day	24% 35% 9% 21% 11%	2786
	11th to 20th	Day	27% 31% 9% 12% 15% 6%	3066
	21st to end	Day	37% 27% 5% 16% 11% 4	4048
January	1st to 10th	Night	29% 21% 8% 26% 14% 2	8234
	11th to 20th	Night	37% 21% 7% 16% 13% 5%	8280
	21st to end	Night	38% 23% 6% 14% 16% 4	9057
February	1st to 10th	Night	19% 59% 5% 9% 7% 1	2611
	11th to 20th	Night	18% 58% 3 8% 11% 2	2460
	21st to end	Night	20% 58% 3 9% 7% 2	2076
March	1st to 10th	Night	37% 29% 6% 10% 11% 6%	5494
	11th to 20th	Night	32% 30% 12% 14% 9% 2	5307
	21st to end	Night	41% 29% 3 7% 14% 5%	5264
April	1st to 10th	Night	23% 59% 3 7% 6% 2	2100
	11th to 20th	Night	18% 60% 6% 7% 8% 1	2075
	21st to end	Night	20% 59% 3 8% 8% 1	1890
May	1st to 10th	Night	43% 26% 11% 11% 8% 1	5265
	11th to 20th	Night	41% 26% 11% 15% 6% 1	5236
	21st to end	Night	45% 25% 9% 16% 5%	5116
June	1st to 10th	Night	17% 59% 5% 11% 9%	1680
	11th to 20th	Night	17% 60% 5% 11% 7% 1	1680
	21st to end	Night	15% 59% 5% 13% 7% 1	1680
July	1st to 10th	Night	39% 24% 10% 16% 11%	4640
	11th to 20th	Night	32% 24% 11% 21% 12% 1	4632
	21st to end	Night	33% 22% 8% 21% 15%	4967
August	1st to 10th	Night	37% 38% 8% 10% 6% 1	2946
	11th to 20th	Night	28% 40% 9% 18% 5%	3083
	21st to end	Night	15% 37% 11% 20% 16%	3677
September	1st to 10th	Night	17% 58% 4 13% 7% 1	2005
	11th to 20th	Night	16% 57% 3 11% 11% 1	2200
	21st to end	Night	23% 57% 3 9% 7%	2200
October	1st to 10th	Night	24% 38% 7% 17% 11% 2	3590
	11th to 20th	Night	12% 35% 5% 18% 27% 3	3949
	21st to end	Night	18% 36% 7% 22% 16% 2	4610
November	1st to 10th	Night	19% 54% 5% 11% 9% 2	2667
	11th to 20th	Night	17% 54% 4 10% 13% 3	2730
	21st to end	Night	17% 55% 6% 15% 6% 2	2730
December	1st to 10th	Night	27% 34% 7% 21% 10%	4612
	11th to 20th	Night	33% 31% 9% 9% 16% 2	5348
	21st to end	Night	35% 27% 5% 16% 14% 3	7150

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	30% 27% 26% 14% 3	220
	11th to 20th	Day	31% 28% 33% 6% 2	220
	21st to end	Day	29% 26% 33% 10% 1 1	242
February	1st to 10th	Day	32% 24% 30% 13% 1	469
	11th to 20th	Day	32% 28% 31% 7% 2	536
	21st to end	Day	30% 23% 34% 11% 3	446
March	1st to 10th	Day	32% 21% 32% 13% 2	540
	11th to 20th	Day	31% 26% 28% 11% 3 1	540
	21st to end	Day	32% 25% 30% 8% 4 2	594
April	1st to 10th	Day	35% 24% 26% 10% 4 1	540
	11th to 20th	Day	31% 25% 29% 12% 3 1	532
	21st to end	Day	28% 21% 31% 16% 2 2	540
May	1st to 10th	Day	33% 24% 29% 11% 3	543
	11th to 20th	Day	25% 19% 39% 13% 3 1	567
	21st to end	Day	21% 17% 35% 20% 5% 1	617
June	1st to 10th	Day	22% 14% 34% 21% 8% 1	570
	11th to 20th	Day	17% 19% 37% 20% 5% 1	570
	21st to end	Day	19% 13% 37% 22% 7% 1	570
July	1st to 10th	Day	19% 10% 32% 27% 11% 1	565
	11th to 20th	Day	16% 10% 33% 28% 11% 2	564
	21st to end	Day	14% 11% 38% 26% 9% 1	620
August	1st to 10th	Day	13% 10% 34% 31% 10% 2	566
	11th to 20th	Day	14% 10% 35% 29% 11% 3	559
	21st to end	Day	13% 11% 37% 22% 12% 5%	619
September	1st to 10th	Day	19% 12% 29% 23% 13% 4	530
	11th to 20th	Day	17% 12% 27% 25% 12% 7%	530
	21st to end	Day	24% 11% 34% 20% 7% 4	530
October	1st to 10th	Day	27% 12% 27% 19% 9% 5%	530
	11th to 20th	Day	21% 17% 33% 17% 9% 2	475
	21st to end	Day	26% 18% 30% 16% 7% 2	462
November	1st to 10th	Day	23% 17% 32% 17% 9% 2	425
	11th to 20th	Day	27% 22% 32% 14% 5%	430
	21st to end	Day	28% 23% 29% 14% 6%	430
December	1st to 10th	Day	25% 28% 31% 12% 5%	287
	11th to 20th	Day	35% 24% 32% 6% 2	220
	21st to end	Day	29% 24% 30% 13% 2 2	242
January	1st to 10th	Night	23% 20% 37% 17% 3	840
	11th to 20th	Night	31% 19% 33% 15% 2	840
	21st to end	Night	23% 22% 35% 17% 3	924
February	1st to 10th	Night	24% 19% 37% 19% 1	840
	11th to 20th	Night	27% 21% 36% 14% 1	823
	21st to end	Night	26% 22% 33% 17% 3	692
March	1st to 10th	Night	26% 19% 35% 17% 3	840
	11th to 20th	Night	23% 22% 35% 17% 3	840
	21st to end	Night	28% 20% 33% 16% 3	924
April	1st to 10th	Night	26% 21% 33% 17% 3	840
	11th to 20th	Night	23% 20% 35% 18% 4	831
	21st to end	Night	24% 18% 38% 17% 3	630
May	1st to 10th	Night	30% 15% 32% 19% 4	630
	11th to 20th	Night	22% 16% 39% 21% 2	622
	21st to end	Night	22% 7% 36% 28% 5%	456
June	1st to 10th	Night	16% 10% 34% 31% 9%	420
	11th to 20th	Night	21% 7% 37% 29% 6%	420
	21st to end	Night	19% 5% 36% 35% 5%	420
July	1st to 10th	Night	17% 4 32% 38% 9%	410
	11th to 20th	Night	16% 4 33% 37% 10% 1	408
	21st to end	Night	16% 4 31% 40% 9%	460
August	1st to 10th	Night	15% 5% 34% 37% 9%	591
	11th to 20th	Night	13% 5% 31% 38% 12% 1	677
	21st to end	Night	15% 7% 26% 36% 15% 2	917
September	1st to 10th	Night	17% 6% 30% 35% 11% 1	800
	11th to 20th	Night	17% 7% 28% 29% 16% 3	800
	21st to end	Night	25% 7% 27% 28% 11% 2	800
October	1st to 10th	Night	24% 11% 27% 25% 12% 2	800
	11th to 20th	Night	20% 11% 35% 23% 11% 1	800
	21st to end	Night	24% 15% 33% 21% 7%	880
November	1st to 10th	Night	20% 15% 32% 24% 9% 1	820
	11th to 20th	Night	23% 18% 35% 17% 6%	840
	21st to end	Night	23% 19% 32% 21% 4 1	840
December	1st to 10th	Night	26% 17% 35% 17% 5%	840
	11th to 20th	Night	29% 18% 32% 19% 2	840
	21st to end	Night	27% 19% 34% 18% 2	924

Page generated at 2026-08-27 04:07:14. Version ac07

Copyright © 2026 Attilla Danko.