Earl Rowe Provincial Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Earl Rowe Provincial Park clear sky chart from 2005-11-06 to 2024-11-25.

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	14% 10% 4 9% 5% 5% 5% 4 6% 7% 32%	102237
	Night	14% 10% 4 9% 6% 5% 5% 4 5% 6% 32%	97226
Transparency	Day	50% 8% 13% 19% 10% 1	105838
	Night	49% 8% 13% 19% 10% 1	101715
Seeing	Day	19% 17% 31% 20% 9% 3	14920
	Night	19% 16% 32% 24% 9% 1	23863

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	15% 14% 6% 14% 9% 6% 4 4 5% 5% 18%	2517
	11th to 20th	Day	10% 18% 8% 19% 10% 6% 6% 3 5% 4 12%	2772
	21st to end	Day	19% 22% 7% 11% 7% 4 4 3 4 5% 14%	3124
February	1st to 10th	Day	12% 17% 4 13% 9% 7% 7% 4 5% 5% 18%	1710
	11th to 20th	Day	10% 14% 7% 13% 8% 6% 5% 4 6% 7% 20%	1663
	21st to end	Day	15% 16% 5% 12% 6% 4 6% 3 5% 5% 24%	1469
March	1st to 10th	Day	17% 13% 6% 10% 5% 5% 4 3 4 5% 29%	3425
	11th to 20th	Day	10% 17% 6% 11% 5% 5% 5% 4 4 5% 28%	3480
	21st to end	Day	13% 12% 4 9% 5% 4 5% 4 5% 5% 35%	3815
April	1st to 10th	Day	15% 14% 4 8% 5% 5% 5% 3 5% 6% 29%	2228
	11th to 20th	Day	19% 11% 3 6% 4 4 3 4 5% 7% 36%	2362
	21st to end	Day	19% 11% 3 6% 5% 4 4 3 6% 5% 34%	2470
May	1st to 10th	Day	16% 8% 3 7% 5% 4 4 4 5% 8% 36%	4108
	11th to 20th	Day	16% 9% 3 7% 5% 4 5% 5% 6% 7% 32%	4356
	21st to end	Day	11% 6% 2 5% 4 4 4 3 6% 8% 46%	4837
June	1st to 10th	Day	15% 7% 2 6% 4 5% 5% 5% 7% 10% 35%	2660
	11th to 20th	Day	11% 5% 2 5% 5% 5% 6% 4 7% 9% 41%	2781
	21st to end	Day	13% 6% 2 6% 5% 5% 5% 4 6% 9% 38%	2850
July	1st to 10th	Day	11% 5% 2 7% 6% 5% 6% 5% 7% 10% 36%	4741
	11th to 20th	Day	10% 6% 1 6% 5% 5% 5% 5% 7% 9% 42%	4440
	21st to end	Day	8% 5% 2 6% 5% 6% 5% 4 6% 8% 43%	4482
August	1st to 10th	Day	13% 7% 3 6% 4 4 5% 5% 7% 8% 37%	4104
	11th to 20th	Day	10% 6% 3 9% 5% 6% 6% 5% 7% 9% 34%	4044
	21st to end	Day	11% 5% 2 6% 5% 4 5% 4 7% 8% 43%	4404
September	1st to 10th	Day	14% 7% 1 7% 5% 5% 4 4 5% 7% 40%	2280
	11th to 20th	Day	12% 5% 3 6% 4 4 5% 4 6% 8% 44%	2142
	21st to end	Day	13% 7% 3 8% 6% 6% 5% 4 6% 8% 34%	2066
October	1st to 10th	Day	18% 8% 3 8% 5% 4 5% 4 5% 7% 33%	1900
	11th to 20th	Day	17% 11% 4 8% 6% 5% 5% 4 6% 5% 27%	1900
	21st to end	Day	23% 17% 4 9% 5% 4 5% 3 5% 5% 21%	2090
November	1st to 10th	Day	12% 13% 4 10% 6% 5% 5% 4 6% 7% 28%	1667
	11th to 20th	Day	12% 15% 4 11% 7% 7% 6% 5% 7% 7% 21%	1600
	21st to end	Day	16% 19% 6% 11% 6% 6% 5% 4 5% 6% 16%	1552
December	1st to 10th	Day	14% 18% 7% 14% 9% 6% 6% 4 5% 6% 11%	1520
	11th to 20th	Day	16% 16% 6% 14% 6% 6% 6% 5% 6% 5% 16%	1906
	21st to end	Day	25% 20% 8% 15% 5% 5% 3 3 3 4 9%	2772
January	1st to 10th	Night	15% 15% 6% 13% 8% 6% 5% 4 5% 5% 18%	4429
	11th to 20th	Night	12% 14% 6% 16% 12% 8% 7% 4 5% 5% 12%	4184
	21st to end	Night	17% 15% 8% 13% 9% 6% 5% 4 5% 5% 13%	4532
February	1st to 10th	Night	12% 15% 5% 13% 8% 6% 5% 4 6% 6% 21%	2470
	11th to 20th	Night	10% 14% 6% 12% 7% 6% 6% 4 5% 6% 23%	2403
	21st to end	Night	11% 13% 4 10% 8% 6% 5% 5% 5% 7% 26%	1983
March	1st to 10th	Night	16% 11% 4 9% 6% 5% 5% 4 5% 6% 30%	3413
	11th to 20th	Night	11% 12% 4 9% 5% 4 4 4 5% 6% 35%	3479
	21st to end	Night	14% 8% 4 7% 5% 4 5% 4 6% 6% 37%	3817
April	1st to 10th	Night	17% 12% 3 8% 5% 5% 4 4 5% 6% 31%	1952
	11th to 20th	Night	16% 8% 2 7% 5% 4 4 4 6% 6% 38%	1782
	21st to end	Night	14% 10% 3 9% 5% 4 5% 3 5% 6% 35%	1710
May	1st to 10th	Night	15% 7% 2 7% 4 4 4 4 5% 7% 41%	2833
	11th to 20th	Night	16% 7% 2 7% 4 4 4 4 5% 7% 40%	2537
	21st to end	Night	8% 5% 2 5% 4 3 4 4 5% 8% 52%	2738
June	1st to 10th	Night	13% 5% 2 7% 5% 4 4 5% 6% 7% 42%	1520
	11th to 20th	Night	9% 4 2 6% 4 4 5% 5% 8% 10% 44%	1393
	21st to end	Night	11% 5% 2 6% 4 5% 4 3 6% 6% 47%	1330
July	1st to 10th	Night	5% 4 2 6% 5% 5% 5% 4 6% 8% 51%	2223
	11th to 20th	Night	11% 4 2 4 4 3 4 3 5% 8% 52%	2520
	21st to end	Night	6% 5% 2 5% 5% 4 5% 4 6% 8% 50%	3054
August	1st to 10th	Night	10% 5% 2 5% 4 4 4 4 6% 8% 49%	2825
	11th to 20th	Night	11% 5% 2 5% 3 4 3 4 5% 7% 50%	2785
	21st to end	Night	11% 5% 2 5% 4 4 4 4 5% 8% 49%	3220
September	1st to 10th	Night	9% 5% 2 6% 4 4 5% 4 7% 7% 47%	1900
	11th to 20th	Night	10% 4 1 5% 3 4 3 2 6% 8% 54%	2035
	21st to end	Night	16% 6% 3 7% 5% 4 5% 3 4 7% 41%	2112
October	1st to 10th	Night	17% 7% 3 6% 5% 4 4 4 5% 7% 38%	2280
	11th to 20th	Night	17% 10% 3 8% 4 4 5% 4 6% 7% 33%	2280
	21st to end	Night	20% 13% 3 9% 6% 5% 5% 4 6% 5% 25%	2508
November	1st to 10th	Night	15% 10% 3 6% 5% 6% 5% 4 6% 7% 33%	2624
	11th to 20th	Night	14% 14% 5% 9% 5% 5% 4 4 6% 7% 26%	2800
	21st to end	Night	16% 15% 6% 10% 6% 5% 6% 5% 5% 6% 21%	2723
December	1st to 10th	Night	17% 16% 5% 12% 7% 5% 5% 4 6% 6% 16%	2660
	11th to 20th	Night	14% 17% 5% 13% 7% 6% 6% 4 5% 6% 18%	3288
	21st to end	Night	25% 20% 7% 15% 5% 5% 4 2 4 4 9%	4884

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	62% 10% 14% 11% 3	2518
	11th to 20th	Day	75% 8% 8% 6% 2	2772
	21st to end	Day	72% 8% 10% 8% 2	3124
February	1st to 10th	Day	67% 8% 9% 12% 3	1710
	11th to 20th	Day	63% 7% 11% 13% 5% 1	1672
	21st to end	Day	63% 5% 10% 14% 7% 1	1469
March	1st to 10th	Day	57% 7% 12% 15% 9%	3428
	11th to 20th	Day	58% 6% 10% 18% 7% 1	3480
	21st to end	Day	49% 7% 11% 19% 12% 2	3815
April	1st to 10th	Day	56% 7% 10% 17% 9% 1	2228
	11th to 20th	Day	49% 6% 9% 21% 15% 1	2362
	21st to end	Day	51% 6% 11% 18% 12% 2	2470
May	1st to 10th	Day	44% 8% 12% 20% 14% 1	4120
	11th to 20th	Day	46% 12% 14% 19% 8% 1	4360
	21st to end	Day	36% 8% 13% 21% 19% 3	4837
June	1st to 10th	Day	41% 9% 14% 20% 15% 1	2660
	11th to 20th	Day	38% 8% 12% 23% 17% 1	2781
	21st to end	Day	41% 7% 14% 23% 14% 1	2850
July	1st to 10th	Day	41% 8% 15% 20% 15% 1	4667
	11th to 20th	Day	36% 7% 13% 33% 10% 1	4365
	21st to end	Day	38% 7% 14% 24% 17% 1	4339
August	1st to 10th	Day	43% 7% 15% 23% 11% 1	4091
	11th to 20th	Day	43% 9% 17% 22% 10%	4083
	21st to end	Day	37% 7% 13% 31% 10% 1	4404
September	1st to 10th	Day	43% 7% 14% 24% 10% 2	2280
	11th to 20th	Day	38% 7% 15% 27% 13%	2142
	21st to end	Day	47% 9% 13% 23% 8%	2066
October	1st to 10th	Day	45% 6% 13% 26% 10% 1	3160
	11th to 20th	Day	44% 6% 15% 22% 13%	3140
	21st to end	Day	60% 7% 12% 16% 5%	3428
November	1st to 10th	Day	53% 9% 15% 16% 6%	1667
	11th to 20th	Day	59% 10% 12% 12% 6% 1	1600
	21st to end	Day	68% 8% 13% 9% 2	1552
December	1st to 10th	Day	73% 8% 11% 6% 1	1520
	11th to 20th	Day	67% 11% 11% 9% 2	1906
	21st to end	Day	80% 6% 6% 7% 1	2772
January	1st to 10th	Night	65% 9% 15% 9% 2	4429
	11th to 20th	Night	72% 11% 9% 7% 2	4184
	21st to end	Night	70% 9% 11% 7% 2	4532
February	1st to 10th	Night	62% 8% 12% 15% 3	2470
	11th to 20th	Night	60% 8% 12% 16% 5%	2405
	21st to end	Night	55% 8% 14% 15% 8% 1	1983
March	1st to 10th	Night	53% 7% 12% 21% 6% 1	3423
	11th to 20th	Night	45% 8% 16% 20% 9% 2	3480
	21st to end	Night	44% 6% 13% 24% 12% 1	3817
April	1st to 10th	Night	54% 6% 10% 19% 11% 1	1952
	11th to 20th	Night	46% 7% 10% 20% 16% 2	1782
	21st to end	Night	49% 7% 11% 16% 15% 2	1710
May	1st to 10th	Night	42% 8% 13% 18% 16% 4	2840
	11th to 20th	Night	40% 10% 14% 22% 12% 2	2538
	21st to end	Night	29% 9% 14% 26% 20% 2	2739
June	1st to 10th	Night	39% 8% 12% 23% 16% 2	1520
	11th to 20th	Night	33% 9% 14% 24% 19% 1	1393
	21st to end	Night	35% 8% 14% 27% 15% 1	1330
July	1st to 10th	Night	31% 6% 15% 26% 19% 3	2188
	11th to 20th	Night	31% 7% 12% 34% 15% 1	2472
	21st to end	Night	32% 7% 14% 29% 16% 1	2957
August	1st to 10th	Night	35% 6% 14% 29% 15% 1	2814
	11th to 20th	Night	34% 6% 17% 29% 13% 1	2812
	21st to end	Night	34% 6% 14% 32% 13% 1	3220
September	1st to 10th	Night	33% 8% 18% 27% 13% 1	1900
	11th to 20th	Night	29% 7% 14% 32% 17% 1	2035
	21st to end	Night	44% 6% 13% 27% 10%	2112
October	1st to 10th	Night	36% 6% 9% 28% 20% 1	3800
	11th to 20th	Night	42% 6% 16% 23% 13%	3779
	21st to end	Night	47% 8% 16% 21% 8%	4120
November	1st to 10th	Night	48% 8% 15% 19% 8% 1	2624
	11th to 20th	Night	55% 9% 14% 14% 7% 1	2800
	21st to end	Night	62% 10% 15% 11% 1 1	2723
December	1st to 10th	Night	67% 9% 14% 8% 2	2660
	11th to 20th	Night	66% 10% 12% 10% 2	3288
	21st to end	Night	80% 7% 7% 6% 1	4884

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	19% 24% 34% 17% 5% 1	180
	11th to 20th	Day	24% 26% 34% 11% 4 1	250
	21st to end	Day	24% 24% 35% 14% 2	297
February	1st to 10th	Day	26% 33% 28% 10% 3	270
	11th to 20th	Day	21% 33% 38% 7% 1	270
	21st to end	Day	32% 34% 27% 8%	225
March	1st to 10th	Day	21% 23% 37% 15% 3	453
	11th to 20th	Day	20% 24% 36% 15% 5%	460
	21st to end	Day	31% 19% 29% 16% 4 1	506
April	1st to 10th	Day	23% 23% 34% 13% 6% 1	460
	11th to 20th	Day	31% 22% 24% 14% 7% 3	452
	21st to end	Day	27% 18% 30% 16% 7% 2	460
May	1st to 10th	Day	21% 16% 34% 17% 10% 2	463
	11th to 20th	Day	18% 13% 32% 23% 10% 3	487
	21st to end	Day	15% 14% 30% 25% 12% 4	529
June	1st to 10th	Day	17% 15% 32% 25% 9% 2	490
	11th to 20th	Day	13% 13% 32% 27% 12% 2	611
	21st to end	Day	16% 14% 35% 24% 8% 3	680
July	1st to 10th	Day	11% 9% 31% 31% 15% 4	665
	11th to 20th	Day	13% 9% 30% 28% 13% 8%	484
	21st to end	Day	9% 8% 33% 31% 13% 6%	532
August	1st to 10th	Day	9% 8% 28% 29% 17% 8%	486
	11th to 20th	Day	8% 8% 28% 27% 21% 9%	479
	21st to end	Day	14% 10% 27% 26% 17% 6%	539
September	1st to 10th	Day	14% 11% 28% 24% 14% 8%	490
	11th to 20th	Day	9% 11% 23% 24% 19% 14%	490
	21st to end	Day	15% 14% 28% 22% 16% 5%	490
October	1st to 10th	Day	21% 17% 26% 20% 12% 4	490
	11th to 20th	Day	20% 23% 33% 17% 5% 2	490
	21st to end	Day	31% 22% 27% 15% 4	539
November	1st to 10th	Day	25% 26% 28% 16% 4 1	257
	11th to 20th	Day	24% 23% 36% 13% 4 1	200
	21st to end	Day	29% 23% 37% 9% 1	188
December	1st to 10th	Day	27% 29% 30% 13% 2	180
	11th to 20th	Day	26% 31% 28% 13% 1 1	180
	21st to end	Day	25% 29% 35% 10% 2	198
January	1st to 10th	Night	22% 26% 32% 16% 4	760
	11th to 20th	Night	22% 23% 31% 20% 3	760
	21st to end	Night	18% 18% 37% 21% 6%	836
February	1st to 10th	Night	21% 24% 37% 16% 1	760
	11th to 20th	Night	19% 23% 39% 16% 3	743
	21st to end	Night	20% 24% 35% 18% 3	628
March	1st to 10th	Night	20% 21% 36% 19% 3	760
	11th to 20th	Night	20% 25% 31% 18% 5%	760
	21st to end	Night	20% 17% 34% 22% 6%	836
April	1st to 10th	Night	24% 19% 35% 20% 2	760
	11th to 20th	Night	19% 18% 35% 19% 8% 1	658
	21st to end	Night	20% 15% 33% 24% 8%	570
May	1st to 10th	Night	17% 9% 30% 32% 11% 1	570
	11th to 20th	Night	17% 8% 33% 32% 10%	403
	21st to end	Night	9% 9% 32% 37% 13%	411
June	1st to 10th	Night	14% 7% 35% 33% 10% 1	380
	11th to 20th	Night	12% 7% 31% 38% 13%	380
	21st to end	Night	12% 7% 31% 34% 14% 1	380
July	1st to 10th	Night	6% 5% 26% 43% 19% 1	370
	11th to 20th	Night	10% 7% 29% 35% 18% 1	368
	21st to end	Night	8% 5% 28% 39% 19% 1	604
August	1st to 10th	Night	10% 4 25% 37% 24% 1	567
	11th to 20th	Night	7% 5% 21% 39% 26% 2	564
	21st to end	Night	13% 6% 29% 29% 22% 1	684
September	1st to 10th	Night	12% 7% 28% 30% 19% 4	760
	11th to 20th	Night	12% 8% 25% 28% 22% 6%	760
	21st to end	Night	18% 11% 22% 28% 17% 3	760
October	1st to 10th	Night	20% 10% 32% 23% 14% 2	760
	11th to 20th	Night	23% 16% 31% 22% 8% 1	760
	21st to end	Night	29% 17% 31% 19% 5%	836
November	1st to 10th	Night	22% 17% 31% 21% 8% 1	780
	11th to 20th	Night	22% 24% 30% 18% 5% 1	800
	21st to end	Night	24% 22% 33% 17% 3	779
December	1st to 10th	Night	26% 22% 36% 13% 3	760
	11th to 20th	Night	20% 25% 35% 16% 3	760
	21st to end	Night	30% 19% 34% 16% 2	836

Page generated at 2024-11-22 08:02:28. Version ac07

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